Philadelphia's Climate in the Early Days

Guest Post by Steven Goddard

January, 1790 was a remarkable year in the northeastern US for several reasons.  It was less than one year into George Washington’s first term, and it was one of the warmest winter months on record.  Fortunately for science, a diligent Philadelphia resident named Charles Pierce kept a detailed record of the monthly weather from 1790 through 1847, and his record is archived by Google Books.  Below is his monthly report from that book.

JANUARY 1790 The average or medium temperature of this month was 44 degrees This is the mildest month of January on record. Fogs prevailed very much in the morning but a hot sun soon dispersed them and the mercury often ran up to 70 in the shade at mid day. Boys were often seen swimming in the Delaware and Schuylkill rivers. There were frequent showers as in April some of which were accompanied by thunder and lightning The uncommon mildness of the weather continued until the 7th of February.

Compare that to January, 2009 with an average temperature of 27F, 17 degrees cooler than 1790.  One month of course is not indicative of the climate, so let us look at the 30 year period from 1790-1819 and compare that to the last 10 “hot” years.

From Charles Pierce’s records, the average January temperature in Philadelphia from 1790-1819 was 31.2F.  According to USHCN records from 2000-2006 (the last year available from USHCN) and Weather Underground records from 2007-2009, the average January temperature in Philadelphia for the last ten years has been 29.8 degrees, or 1.4 degrees cooler than the period 1790-1819.  January, 2009 has been colder than any January during the presidencies of Washington, Adams, Jefferson, or Monroe.  January 2003 and 2004 were both considerably colder than any January during the terms of the first five presidents of the US.  Data can be seen here.

According to several of the most widely quoted climate scientists in the world, winters were much colder 200 years ago than now – yet the boys swimming in the Delaware in January, 1790 apparently were unaware.

Another interesting fact which can be derived from Charles Pierce’s data, is that January temperatures cooled dramatically during the period 1790-1819 – as can be seen in the graph below.  The cooling rate was 13F/century.  What could have caused this cooling?  We are told by some experts that variations in solar activity can only affect the earth’s temperature by a few tenths of a degree.  CO2 levels had been rising since the start of the industrial age.  The downward trend is fairly linear and does not show any sharp downward spikes, so it is unlikely to be due to volcanic activity.  What other “natural variability” could have caused such a dramatic drop in temperature?

Looking at the sunspot records for that period, something that clearly stands out is that solar cycle 4 was very long, and was followed by a deep minimum lasting several decades.  Perhaps a coincidence, but if not – Philadelphia may well be in for some more very cold weather in coming winters.
Source for graph:

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Now that is very interesting. Keeps getting back to Sunspots, because there definitely wasn’t significant amounts of anthropogenic CO2 being produced by industry back then….
Probably won’t find this in the mainstream media, well not until they decide to create an Ice Age bandwagon and make a catastrophe out of natural variation and jumble science with fantasy again.
…. Anyway, it’s kind of reassuring to know that we’ve been there before.

Graeme Rodaughan

How long before some one claims Charles Pierce was a schill for big oil?
It will be interesting to see how this evidence is discounted.


Thank you for this wonderful post.
IMHO, there is one factor that makes a direct comparison between the Pierce records and today impossible; the urban heat island effect. In other words, the UHI is surely making today’s data for the city warmer than it otherwise would have been. If I’m right on that, the real temperature difference is therefor larger than you have shown, and the cooling even more significant.
Is it just me, or does Solar Cycle 4’s decline look very similar to 24’s? the shape of the slope looks very similar to me.

Steve Berry

OT. HadCruT finally in! Scroll to the bottom – right hand side. All those 0.4s, then a 0.3!


Well it wasn’t the sun. That giant flaming ball that is so big that our entire planet could fall into it and not even make a respectable splash couldn’t possibly affect things here.
Since the cooling was harmful and caused crop failures and other problems, it has to have been anthropogenic. My guess is soot from burning coal.
(and for the humor impaired, yes, this was intended as sarcasm)

Rob R

How did Pierce do his measurements?

Mike McMillan
. . . It may be cold comfort during a frigid February, but last month was by far the hottest January ever. . . . The scientists went beyond their normal double checking and took the unusual step of running computer climate models “just to make sure that what we’re seeing was real,” Easterling said.


Ralph B.

I do not understand something…I have read several articles (here and elsewhere) showing sunspot numbers and temperature following each other. What we have not yet found though is why that is. If it was just once then it would be coincidence but from the graphs I have seen global temps seem to follow sunspots. I hold Leif in high regard and he has thrown the BS flag on just about every instance of attempted correlation. Whats more he backs up his flag with his version of instant replay…hard data.
Is there something that we just haven’t looked at yet?

Peter McWilliam

Dear Anthony
Just about OT but more an excuse to indicate another impressed learner lurking.
Do Tambora in 1815 and the year without a summer in 1816 show in those records.
In Ulster/Ireland there was a famine in 1817 – I suppose following a reduction in temperatures in 1816
I have seen some contemporary weather notes made by a relative and 1816 isn’t mentioned as unusual which has always puzzled me


I wonder if Pierce attempted to influence the nature of the measurements….

Pierre Gosselin

That was very intersting. I wonder how many such old diaries exist worldwide.
Such spells of unusual warm, or cold, weather can be found anywhere. Unusual weather is in fact not unusual.
If the observations mentioned above occurred today, or especially when Gore testifies this week, think of the doomsday panic he and the media would try to unleash.
But when Gore testifies later this week, looks like more cold weather.
If we are lucky, the heating system will bonk out just before Gore testifies.

Freddie S.

Good Job, as allways very interesting. By teh way, we have some very good records in Switzerland, they are accessible via : on top one can choose the language. One station reaches back 150 Years, not much warming there? Keep the pressure up.
Regards from the cold snowy Swiss Mountains. Freddie


This morning several Maine stations are again establishing new record daily lows. It’s becoming commonplace this month.

John Finn

Steve Goddard
Before we start blaming the Dalton Minimum – what was the pennsylvania record like before and after the DM period.


Sorry O/T but an excellent round up of research into the UHI in North America can be found on “CO2 Science”.

Robert Bateman

What you haven’t looked at yet is the rest of the records from around the world. Especially for the decade of the 1790’s, which is noted in literature in places such as Russia, China, India, Japan, Australia, etc.
Else you are going to get hit with cherry-picked data every time from anyone wanting to whip the rug out from underneath.
Remember, climate is the whole enchilada.
Put it all together and the graph from Philadelphia might look like the best case scenario for a warmist point of view.

David M. Ludlum wrote a series of American weather books, one of which is titled, “Early American Winters: 1604-1820.” In it he tells the tale of the winter of 1779-80, when the snow started falling in November and just didn’t stop. This is the winter after Washington’s storied Valley Forge freezeout. Washington’s troops were wintering in Morristown, N.J. — one writer said it made Valley Forge of the previous year look like a picnic.
All of the New York harbor from New Jersey to the lower section of Long Island Sound was frozen to the point of cavalry and multiple cannons being hauled between Manhattan and Staten Island, and several Hessian troops abandoned their posts and walked the 12 miles across Long Island Sound from Lloyd’s Neck to Stamford, CT. Ludlum says that the Connecticut Courant in Hartford provided the most complete temperature record. The temperatures reportedly reached 16 below zero. Even if that temperature isn’t completely accurate to the degree, it was obviously as cold as the severe cold the New York area suffered through in the winter of 1933-34.
I wonder how 1779-80 and 1933-34 fall as to solar minima and maxima. After all, they’re just local weather events.

Robert Bateman

For the Western World, the data is being cooked right before our very eyes to meet political agenda.
For the Russians, they are noting with grim determination what is coming down the pipe, and they are banking on it, literally.
Kinda makes you wonder, does it not?


Pierre raises an interesting point. Can anyone suggest where would be the best place to look for old records which can be compared to this period? It does seem to keep coming back to sunspots. No idea why. how, etc. and correlation is not necessarily causation, but the current period is freezing my butt, and putting paid to the AR4 projections. -24C this morning. Not pleasant.

Claude Harvey

Response to Rob B. question
As I understand the sunspot/global temperature theory, it goes as follows and is based on the idea that low-level cloud cover is the earth’s primary temperature control mechanism:
Cosmic radiation “seeds” such clouds. Solar wind generated by sunspot activity diverts cosmic radiation away from the earth. Fewer sunspots translates to more low-level cloud cover and lower temperatures.

A very interesting article, which shows us that before the 20th century there was not some sort of climatic Golden Age, with predictable mild springs, warm summers and snowy winters every year (and which, according to AGW theory, was thrown out of kilter by industrialisation and CO2.) The amount of variability appears to have been huge, in the 18th and in any century. In 1776, Washington’s army was crossing the Delaware, which was swarming with ice floes; in 1777-78 they were freezing in Valley Forge. The mild January of 1790 would probably have got people sounding the alarm about CO2-induced “climate chaos”, had the same pattern occurred 200 years later.

Chris H

@Ralph B. (02:24:57)
Sunspot correlations are only approximate at best, and rely on an 11-year running average, but there does seem to be a rough correlation. Of course we must expect that other things also affect temperature, so trying to make disproofs of sunspot correlation based on a few years of data is misguided.
Hopefully we find a better solar measurement than sunspots for predicting temperature, but then we will only have data going back a few decades (which makes proof/disproof hard – perhaps harder than sunspots, since short-term variations in temperature caused by other factors will make such predictions harder).

Dan Lee

Ralph B.
As I understand it, the objection to the sunspot-temperature correlation being meaningful (in the scientific sense) is that we don’t have a mechanism to explain it. Obviously the correlation is there, but is there some third factor we haven’t found yet that explains both? Or do two long-term cycles happen to be coinciding for the last couple of hundred years that make it only look like there is a connection? Until a mechanism is proposed and confirmed, we won’t really know.
To find a mechanism by which solar cycles influence climate, someone would need to come up with an hypothesis that demonstrates how solar variability might cause (for example) water molecules to behave slightly differently to produce an overall warmer or cooler effect, or perhaps more or less wator vapor in the atmosphere, which over time influences the climate. Something like that.
Some kind of mechanism is needed, a testable hypothesis, before we can really call it science. The correlations tell us that something is going on (maybe), but until we have a mechanism, we’ll never be quite sure what, and we’ll never really be able to make accurate predictions.

Ron de Haan

Thank you Steven Goddard for this fine article,
The most essential point made is the fact that our current temperatures are well within “NORMAL” parameters and AGW is a “HOAX”.
Forget the endless discussions about CO2 and if you have any doubts left pay a visit to the web site of the late John. L. Daly:
Although most temps end by 2001/2002 you will see that most temps (raw data) are…flat and many of them show cooling, a trend that continues today.
Also read the article “On top of the world” about the Arctic or any other article of interest.
It’s nice to see that AGW has an history and the warmists have created a habit to keep pushing for the same subjects over and over again to make their point.
Scaring the public with non existing catastrophic events based on rigged data to serve a political agenda!

Adam Gallon

It’d be interesting to see if there is any correlation between tree-rings and temperatures in the vicinity covered by this and other diarists.


The chart might be even more interesting if we accounted for a UHI factor. Of course, we also need to check where Charlie was living in Philadelphia, how he measured the temperature, and where he kept his air conditioner and barbacue grill.
It might be interesting to run a thread on historical records – say anything before 1900.
OT, can anyone tell me the accuracy of the temperature reading on automobiles – 2000 Audi A6, to be precise.

Pearland Aggie

Dr. Masters over at Wunderground is a big AGW proponent…I’m not sure he’d appreciate how you used the temperature records on his website! 🙂

Adam Gallon

an interesting snippet from the link to the John Daly website.
Vardo, in Norway shows the similar “hot” 1930s.
Likewise Haparand in Sweden, , London (The Cannuck one), where there’s a “warm” winter in ’32, Port Stanley in the Falkland Isles shows a “cool” period in the mid ’30s and a sharp warming in the mid 40s.
Interesting. A few places do show a definate, steady rise over the past 150 years, but only by a degree C or so.

John M

Nice article!
I’m in my “colonial” period of American History reading and have been struck by the meticulous attention to weather and note-keeping of both Washington and Jefferson. Also, it was no secret that Philadelphia was a horrendous place to be in summers during the colonial period, as anyone who’s read David McCullough’s John Adams would know. Al Gore would have had a field day holding hearings in the stifling heat.
I’ve recently finished George Washington’s War by Bruce Chadwick, which contains many accounts of how weather influenced the course of the Revolutionary War. What strikes me about this history is that, despite the fact that we generally consider the 18th century as the tail-end of the Little Ice Age, the real take home message is…wait for it…weather is a story of extremes. And even in a period that virtually everyone acknowledges as a cold period for the northern hemisphere, the stories are almost as much about unusual warmth as about extreme cold.
Most Americans know that Washington led a crossing of the Delaware River on early Christmas morning 1776 amidst ice floes, but most don’t know the equally impressive feat of escaping to Morristown in the slogging muck that followed as a result of a warm spell the week after. From years of note-taking while running his Mt. Vernon estate, Washington recognized a narrow window for escape on frost-hardened ground, which quikly warmed and caught the British in a quagmire.
Most Americans know about the bleak winter at Valley Forge, but that winter was described by Chadwick in this way:

Although there were sevearl days of bone-chilling weather, the temperatures recorded during those months was not unusually low, and many soldiers used phrases like “pleasant for the season” to note the mildness. Sgt. Ebenezer Wild kept a diary that showed mild temperatures (“very fare and pleasant”) on eleven of the first fourteen days of January. The Valley Forge winter, despite the folklore that surrounded it, was actually quite moderate.

Chadwick references a meterologist/historian, the late David Ludlum, whom perhaps Anthony is aware of. The actual reference in the book is from a 1975 edition of Weatherwise, but similar works appeared more recently. It appears that the online archives for this magazine only go back to the 90s.
Here’s Ludlum’s obituary and a couple of articles in the archives of the magazine.
NYT obit
Weatherwise citations

John M

Looks like the second link may not be active. Here’s the search page for the magazine. Just search: Ludlum independence.


Peter (04:23;06) asks:
“where would be the best place to look for old records which can be compared to this period?”
I spent a couple of satisfying afternoons at the local library going through microfiche records of our local paper. Armed with only a few dates in mind, I poured through 1930’s edition reading about the “great” heatwaves and record high temperatures and the drownings and deaths before the era of air-conditioning. Just those two episodes convinced me that the doctoring of our climatic record is a criminal act.

Its nice to se the interest in this thread but I am slightly surprised that people are so amazed by the data as it has been posted numerous times here and elsewhere. Generally it is derided by warmists as anecdotal-even when it is stitched together with other information to create a composite overview covering huindreds of years it is still considered ‘unreliable’ when comopared to…err…the Mann Hockey Stick.
The fact remains that there are many thousands of such records from reliable sources to show that climatically we have been this way many times before and that even during what we understand to be the LIA there are temperatures equivalent to todays, without even getting into the evidence of the MWP’s warmer values.
This link shows actual unsmoothed Hadley CET data to 1660.
This shows the Zurich Switzerland figures to 1860 -adjusted for the enormous UHI influence at 0.4C total since 1970-probably a very modest adjustment.
Here it is unadjusted
Here is the zoom view that enables people to see the enormous growth round the station (fluntern) Historic note; James Joyce is buried here and Lenin and Trotsky took refuge in Zurich in World War 1
Here is Fluntern compared to Hadley- demonstrating the atonishing mirroring until modern UHI affects Zuruich more than the CET in the 1970’s onwards.
CET is said to be ‘indicative’ of the western hemisphere.
I have numerous records of Historic temperatures and have done much research of my own. Fish are a very good indicator of climate change, so those on the coast can check local records to see that fluctuating temperatures are marked by changes in fishing pattern
Pilchards warm weather-
Co for cold waters.
Many readers here will know of my complete lack of regard for the artificially concocted global temperatures to 1850 on which so much of the historical ‘evidence’ for modern warming is based. Consequently I am collecting reliable national and regional temperature data sets-the longer the better-so if if you know of any please provide a link which I will produce as a resource

Pierre Gosselin

I know that old monastaries in Europe kept such records going way back. But that would be rather local. I wonder if any historical archives in other areas like New England, China, Arabia etc. would have such records. I would think they surely do. Something for scholars to research.
C.H. Beck has written book called:
Kulturgeschichte des Klimas
(Cutural History of the Climate).
Unfortunately written only in German. In this book he cites many historical written records from various European archives. Of course, the written records contradict what Mann’s hokey stick claims.

Pierre Gosselin

I meant hockey stick

Even NASA not long ago believed there was a significant solar forcing.
see also:

Steven Goddard

Charles Pierce records begin in 1790. The Delaware River just outside Philadelphia is currently frozen over, which provides a good reference point vs. boys swimming in January, 1790.

Claude Harvey

One of the problems with correlating sunspot activity with global temperature has been the complication of volcanic eruptions, which are known to cause short-term cooling through cloud-seeding effects. There is a study out there (can’t lay my hands on it at the moment) which purports to have tuned out the volcanic effect and have produced a very good correlation between sunspot activity and global temperature.


One would be hard pressed to find a continuous record such as one in Philly. Europe has a much better record. I know Oxford has created some forensic synoptic weather maps for Europe based on a mix of ship logs and farmer’s diaries. While farmer’s diaries are very subjective, they can give the reader a broad based idea of weather conditions. Important things such as first and last frost of the growing season, crop yield problems due to drought or frost, as well as basic entries covering cloud cover, fog, wind direction, etc.. can give the forensic meterologists a fairly good idea of climate patterns. There are pitfalls, such as comments like “coldest winter in memory”; or “driest July since my grandfather’s time.”
Climate scientists usually scoff at such things as farmer’s diaries as an anecdotal, but like the Philedelphia’s weather records they are real and not computer modeled output. They are in no way percise. But niether are Mann’s PCAs, Hansen’s Temp reconstructions, or Steig’s back-filled temp grids.


Very interesting piece of information! However, I doubt that the changing temperature of a single city requires much in the way of a climatological explanation that would be broad enough to effect world-wide temperatures.

I posted a number of references and links to historic temperatures a little while ago. Have you moderated it for some reason or has it just disappeared into the ether due to climate change?

Bill in Vigo

Yep this is very interesting data. I wonder if there are folks at Giss that have noticed this record and just how they would homogenize it. If I understand homogenization it means to blend and cook a liquid to prevent any changes or corruption of the mix of components. Therefore there will be no resemblance to the natural variation that would have appeared with out the homogenization. Not so sure homohenization is the way to study temperature.
Mean while here in N E Alabama of the 26 days of January thus far we have had 13 pipe bursting low temps well below seasonal lows and only 13 days with highs at or above seasonal highs. For those of us here in this area/region this has not been the warmest Jan. on record by a long shot.
Just thinking about things.
Bill Derryberry

Evert Jesse

Ralph B, Chris H, Dan Lee,
Is it conceivable that the heat in the core of the earth itself is a driver for climate changes? I have no suggestions on possible mechanisms, be it underwater volcanoes, plate tectonics or thickness variations of the crust, but the fact is that –contrary to the sun- this energy source is close to the surface of the earth, and for a large part hidden from direct observation. I’ve heard the statement that we know more about the surface of Titan than of the bottom of the sea. Different ocean currents, be it PDO or AMO, can then transfer and distribute the heat dependent on their flow directions; possibly they are influenced or even caused by this effect.
Energy from the centre of the earth must transfer to the surface, as the crust will not be a perfect isolator. The questions are whether the rate of heat transfer is sufficient to influence the global temperature and whether there would be a mechanism which induces variability of this rate in time with observed long and short term global temperature changes.
By itself this does not explain the observed correlation of global temperature changes with solar activity, but at least it provides a possible additional source of energy to explain climate variations.
I have now followed the climate discussions for well over a year now, and I have so far not come across such a hypothesis, apart from references to underwater volcanoes. Simple Google searches have not yielded more info. Was such a theory discussed and rejected before my time, have I just missed something, or is it so obviously right or wrong that no one discusses it anymore?
Please comment

Ed Scott

Climate, Carbon, Solar Cycles, Man Made Global Warming
Recycling Climate Change for Profit
By Dr. Tim Ball Monday, January 26, 2009
It is generally agreed that changes in the sun/earth relationship are the major mechanism driving long-term climate patterns. These are collectively known as the Milankovitch Effect and include; changes in the Earth’s orbit caused primarily by the gravitational pull of Jupiter with a 100,000-year cycle; changes in the tilt of the Earth of undetermined cause, with a 40,000- year cycle; and a shift in the date of equinox with a 19,000-year cycle. Although Milankovitch’s work was initially accepted it lost favor when his results conflicted with some radiocarbon data. I recall conferences in the 1980s when reference to Milankovitch brought vigorous protest. However, by the 1990s he was back in favor.
IPCC 2001 “The Scientific Basis” says “In climate research and modeling we should recognize we are dealing with a a coupled non-linear chaotic system, and therefore that the long-term prediction of future climate states is not possible.”
It’s statistically easy to detect cycles within this graph. Some of them seem visible. The challenge is to identify the cause of these cycles, as they are the net result of a myriad of cycles, including the Milankovitch Effect and sunspots cycles. One thing we know is they don’t fit the CO2 pattern.
So just one apparently simple media article illustrates Schweitzer’s point. They also confirm Rutherford Rogers claim that, “We’re drowning in information and starving for knowledge.” The lack of knowledge does not prevent governments forging ahead based on the completely unwarranted certainty of the IPCC and proponents of AGW.


A further €175bn a year needed to tackle warming and most of it should come from industrialised nations, EU zone.

Bill Illis

One of the longest temperature records is the trading posts along Hudson Bay – Churchill and York Factory. The Hudson Bay Company and the Royal Society of England didn’t believe the temperature reports from the traders and they were still thinking about the NorthWest Passage so they established a project to measure temperatures at these forts – some of the records have gone missing but here is a temp record from the arctic going back to 1769.

Pamela Gray

Good heavens. The entire class of students raised their hands and not one came up with the “first encountered pathology”. Both the jet stream AND the pacific oscillation affects Philadelphia. Other than the Great Lakes snow affect, the weather patterns you all get in the East comes from the frontier. The wild wild west. And the jet stream is often affected by Arctic dips that can take a month to scrub out. I am also thinking that the jet stream may be affected by frontal systems stemming from where cold and warm ocean currents meet. If a cold pacific equatorial current pushes that cold/warm boundary North maybe the jet stream follows? It would be fabulous to study jet stream behavior during oscillation changes. Which comes first? And since oscillations stay around for years, weather patterns stay around for years. Climate in the East has not changed (for several geological reasons). But apparently the weather patterns in an around Philadelphia within that stable climate have cycles. The Sun may or may not be the driving factor as it may have an affect on cloud seeding and atmospheric breathing patterns, and these are questions that still need to be answered. But we should be studying the first encountered pathology “first”. Class dismissed.

Pamela Gray

I can see that before my post was accepted, other posts just before began mentioning oceanic oscillations. Good. But it still surprises me that it took this long. This may be my own lonely soap box, but unless a plot of ground changes latitude, altitude and/or proximity to a large body of water, the climate will be stable within 10’s of 1000’s of years. It is the weather pattern that changes. Local geology, plate tectonics, and large scale global tilt can and do plunge regional stable climates into new climate zones. But it is my opinion that what we are talking about at this science blog, and what the AGW’s are talking about, are weather patterns. And by and large, the largest driver of weather patterns are the jet stream, and oceanic oscillations. Any other heating or cooling source is drowned by these two drivers. It remains for us to understand these drivers first, and then to talk about and study what might drive the drivers.

You can find here: a graph with the temperatures records of Lima City (South Anerica, Long:75°, Lat:12°) from 1754 to 1856.

P Folkens

The warmth of the latest 18th Century was also shown in Rhodes Fairbridge’s reconstruction of Late Holocene sea levels published in Science in the late 1970s.
The winter of Washington’s stay at Valley Forge (1777-78) was considered the coldest anyone could remember. It too seems to fit well with the sunspot minima of that decade as does the warmth of the 1790s.
Also to Pierre Gosselin (05:55:11): “hokey stick” works fine for me.

Jack Wedel

Bill Illis: I’m sure you’d find Dr. Tim Ball’s Phd thesis of interest. It was founded on temperature/climate data obtained from Hudson Bay company archives of trading post records from York Factory.