Guest Post by Willis Eschenbach
In the comments of my last post entitled “Spot The Volcano, 1815 Edition” someone mentioned that Thomas Jefferson had commented on what is often called the “Year Without A Summer”. This was the summer of the year 1816, one year after the eruption of Mt. Tambora in Indonesia, which occurred in April of 1815.
Some research turned up Jefferson’s weather notebook entitled “Analysis of Weather Memorandum Book, January 1817”. All of the data in this post is from his analysis. He opens by saying:
1817. January. Having been stationary at home since Mar.1 1809. with opportunity and leisure to keep a meteorological diary, with a good degree of exactness, this has been done: and, extracting from it a term of seven years compleat, to wit from Jan. 1. 1810. to Dec. 31. 1816. I proceed to analyse it in the various ways, and to deduce the general results which are of principal effect in the estimate of climate. the observations (3905. in the whole) were taken before sunrise of every day; and again between 3. and 4. aclock P.M. on some days of occasional absence, they were necessarily omitted. in these cases the averages are taken from the days of the same denomination in the other years only, and in such way as not sensibly to affect the average of the month, still less that of the year, and to be quite evanescent in their effect on the whole term of 7. years.
In other words, a good and careful observer. In addition, he took the maximum and minimum values at the same times of day, before dawn and between three and four o’clock. Well done, that man.
Since our interest is in the summers, the first graph that I made up from Jefferson’s data is of the May to September growing season in Monticello (see below for growing seasons). Here are the temperature means, minimums, and maximums.
Figure 1. May to September average temperatures at Monticello, Virginia, as recorded by Thomas Jefferson. Horizontal straight colored lines show the averages from 1810 to 1815.
Now, Figure 1 shows some interesting things. The average May to September temperature (yellow line) in 1816 was about the same that of 2015. However, the maximum temperature is about a degree warmer than 1815, and the minimum temperatures were about a degree lower than in 1815. Max goes up, mean unchanged, but the minimum was unusually cold. In particular, the months of July and August had cold minima. So Tambora may have had some effect on temperatures at Monticello.
Jefferson also recorded some other interesting weather data. He wrote down the days of “white frost”, also known as a “killing frost”. He recorded the last day of white frost in the spring, and also the first day of white frost in the fall. This lets us see if 1816, the “Year Without A Summer”, had killing frosts later or earlier than other years. Here’s that information.
Figure 2. Days of the first and last frosts at Monticello, Virginia, as recorded by Thomas Jefferson.
The year 1816 was not at all unusual as regards to frost. The last frost of the spring happened around its usual time. And although it had the earliest fall frost during the period, as Jefferson commented, “but we have seen, in another period, a destructive white frost as early as September.” Not to mention that the growing season was the fourth longest of the seven years of record.
How about rainfall? Here are the month-by-month values:
Figure 3. Monthly rainfall at Monticello, Virginia, as recorded by Thomas Jefferson.
I’ve highlighted the June to August periods because that period was indeed unusually dry in 1816. However, both May and September 1816 were unusually wet, and the year 1816 overall had the fourth highest annual rainfall of the seven years.
Finally, Jefferson considered that when the temperature was below 55°F you’d need a fire. So he listed the number of times that a fire would be necessary, both in the morning and in the afternoon. In his words:
“It is generally observed that when the thermometer is below 55.° we have need of fire in our apartments to be comfortable. in the course of these 7. years the number of observations below 55.° in each year were as follows.”
Here are the number of days per year that Jefferson thought would require a fire either in the morning, the afternoon, or both:
Figure 4. The number of days requiring fires in the morning and the afternoon at Monticello, Virginia, as recorded by Thomas Jefferson. Photo shows one of the many fireplaces in Jefferson’s home at Monticello.
As you can see, 1816 required the least morning fires of the seven years, and it only needed an average number of fires in the afternoon.
So … the growing season of the year of 1816 was dry and had both cold and warm months. In the fall of that year, before he wrote the summary of the data used in this analysis, Jefferson commented in a letter to a friend that “We have had the most extraordinary year of drought and cold ever known in the history of America.” However, his own records show that, as is the habit of humans the world over, he was exaggerating … shocking, I know, that a US President would exaggerate … but I digress.
I say he exaggerated because contrary to his claim, the facts in his meticulous recordkeeping for the year 1816 show less than a half-degree C of May – September cooling, no unusually late or early frosts, an average length growing season, no need for extra fires in the morning, and fewer fires than usual needed in the afternoons. And although June through August was dry, overall the year 1816 was fourth among the seven years in the total amount of rain.
So was there a “Year Without A Summer” at Monticello?
I’d say that the eruption of Tambora may well have some effects at Monticello, with a couple of quite cold months and a couple of quite dry months, but the reports of those effects have been greatly exaggerated, even by Thomas Jefferson himself …
My warmest regards to all,
w.
PS—When you comment, to avoid misunderstandings, please quote the exact words that you are discussing.
I read somewhere that eruptions in the tropics don’t have much effect on world temperatures, try a volcano in the high latitudes.
It used to be thought that only tropical eruptions could affect both hemispheres. But now it appears that, under the right conditions, high latitude eruptions can as well. Or at least they can affect the tropics.
https://phys.org/news/2017-11-high-latitude-volcanic-eruptions-global-impact.html
What we are analysing is subjective impressions vs objective recordings. What people remember is the odd extreme event, whereas averages don’t mean very much and are easily forgotten. In a month of days where the weather is slightly warmer, the few cold days will be more memorable – and vice-versa. There is also the issue of outlook: to an optimist a day with mostly sunshine and a shower at lunchtime is a sunny day, to a pessimist it is a wet day. This is particularly relevant when it comes to social pressure to conform – if everyone is saying, “phew what a scorcher” because it was hot at midday are you going to argue that you were cold that night and needed a blanket (OK, some of us ‘ornery types might, but we will get ignored the way that we are doing at the moment!)
I know we have to use averages to look at the bigger picture of climate, but they are meaningless statistical constructs when it comes to the effect of weather on personal experience.
https://www.google.com/search?q=British+priest+documents+the+year+without+a+summer&oq=British+priest+documents+the+year+without+a+summer&aqs=chrome.
Instrument measurements and average temperatures don’t tell the whole story. You could do a similar analysis of other major volcanic eruptions and the Little Ice Age and would likely find that temperatures and growing seasons were not unusually different in many places. But in some regions they were significantly different. Just like numerous historical records report unusually cold winters in some places during the Little Ice Age (ice festivals on the Thames), there are historical records of disastrous crop failures in 1816, the “Year Without A Summer,” that resulted in migration to other places in search of better opportunities. The Dust Bowl years were similar. Whether or not average temperatures or temperature extremes were significantly different, there were undoubtedly weather extremes that caused widespread hardship. These may or may not directly correlate to, in the case of 1816, a volcanic eruption; but the misery was widespread and a matter of historical record.
JT:
1°F per century. There you have it, global warming, the science is settled. Too bad the more accurate modern methods still haven’t adequately explained this “curious fact in physical history.
How long is the growing season in Monticello today?
True enough. I think it is some other type of degradation of that causes the deviation in mercury thermometers. Must admit that I cannot remember now what it was. I do remember getting irritated by the endless yearly quality checks on theremometers during the relevant audits.
Henry, I wouldn’t worry too much about it. As Lord Monckton said, we are now in the Adjustocene era. There are no temperature records in existence that NASA and NOAA and several others can’t alter to suit the needs of the CAGW agenda.
https://wattsupwiththat.com/2018/08/21/temperature-tampering-temper-tantrums/
Gary
I think it was the reaction between the mercury and the glass…sorry I forgot.
Obviously that is the reason why we stopped using them. We are now using thermocouples. I take it that they are used now exclusively in weather stations?
The last killing frost in 1813 was the beginning of Feb???? Think of the warmunists & eco-loons today wringing hands and crying about that. Oh no! The world is going to FRY!
Readers might be interested in reading first person accounts of the Battle of Waterloo which occurred on June 18, 2015 in Belgium. The eruption certainly didn’t negatively affect the crops that year in that area.
More than one account talks about the height of the grain having an affect on the course of the battle.
At Quatre Bras “the rye in the field was so high” Llewellyn of the 28th Regiment remembered, that….the enemy…were obliged to make a daring person ride forward to plant a flag as a mark, at the very point of our bayonets”
“the light company of the 51st Regiment….was fired on by the French infantry which had got unscathed to within forty feet of their line under cover of the standing grain”
From The Face of Battle by John Keegan
Gene Selkov says
https://wattsupwiththat.com/2019/01/28/president-jefferson-meets-mount-tambora/#comment-2608368
Henry says
please note my comments to Gary just before &
depending on the height of temperature that the thermometer was eposed to, the amount of reaction of the glass [which also contains oxygen] with the mercury might be variable….?
Like I said, I also thought the yearly audits were rediculous but my thermometer to determine viscosity was only used ar 25 +/- 0.1 degrees C, constantly. So, I never seeing any differenec I was inclined to think that the deviation as reported was non-existant.
Mary Shelley commented upon the weather of Summer, 1816, in the preface to the 1831 edition of Frankenstein. https://www.rc.umd.edu/editions/frankenstein/1831v1/preface
“I passed the summer of 1816 in the environs of Geneva. The season was cold and rainy, and in the evenings we crowded around a blazing wood fire, and occasionally amused ourselves with some German stories of ghosts, which happened to fall into our hands. These tales excited in us a playful desire of imitation. Two other friends (a tale from the pen of one of whom would be far more acceptable to the public than any thing I can ever hope to produce) and myself agreed to write each a story founded on some supernatural occurrence.
“The weather, however, suddenly became serene; and my two friends left me on a journey among the Alps, and lost, in the magnificent scenes which they present, all memory of their ghostly visions.”
I’d say that account speaks of a summer with extreme cold spells. That sounds like one of John Tillman’s references, http://www.newenglandhistoricalsociety.com/1816-year-without-a-summer/ . Cold, warm, cold, warm ….
If you’re farming, you don’t need a uniformly-cold summer. A summer with a few really bad frosts can do you in just as well.
President Jefferson was certainly aware of the weather. He had Rumford fireplaces constructed at Monticelli.
“Jefferson’s remodeling notes for Monticello, begun in November of 1796, contain sketches and notes for “Count Rumford’s fire places in the square rooms”;3 another “Design for Chimney and Flues,” externally dated to 1797, also contains drawings and notes for a Rumford-style fireplace.”
https://www.monticello.org/site/research-and-collections/sir-benjamin-thompson-count-von-rumford
Ellen
there is nothing you can do about natural climate change, except be warned about it ahead of time;
if we can people to stop putting money on this man made climate nonsense and focus on looking at natural solar cycles, like I am saying:
There is going to be major drought time, on the great plains of north America starting just about this year or next year
2019-87 = 1932
[Dust Bowl drought 1932-1939]
1932-87 = 1845
https://www.researchgate.net/publication/286971648_Drought_in_the_western_Great_Plains_1845-56_Impacts_and_implications
that drought period was from 1845 until 1856
I think I heard somewhere on this page now about a drought that played out in in Virginia from 1755 onward. True?
Co-incidence?
Or Gleissberg solar cycle? {the GB cycle is calculated by me and others as being about 87 years].
The extra record cold [winters] as predicted by me now have already started. The dry summers are lying ahead.
http://breadonthewater.co.za/henrys-climate/
I hope you come right:
moving south, I would say…
This was not especially responsive to a quote from Frankenstein.
Off topic but a mind boggling read from the BBC – How colonization of the Americas caused the Little Ice Age
https://www.bbc.com/news/science-environment-47063973
I wrote an article that was published back in the early 90s. It was on-line, but has been taken off. I studied Iowa tree ring data, and I remember the extremes into about 1820. Growing conditions for trees in Iowa were terrible just following the 1815 time. I also used monthly average corn prices in that study, and I remember the high being (in 1815 dollars) $1.05/bushel.
It certainly, from what I saw, had to have been a memorable time.
Dear Willis, thank you for taking the time and converting Jefferson’s weather data into graphic formats, he certainly was a most careful observer and and used the best instruments of his time. Weather observations for a plantation owner was most important, as such his comment (of which you made fun of) needs to be taken seriously and put into context. As of 2009, the Monticello foundation has this letter reprinted in more detail, see below and it becomes clear that he was not simply comparing annual averages but rather commenting on dramatic weather events which directly effected the purse of a land owner in these days.
In particular your comment “And although June through August was dry, overall the year 1816 was fourth among the seven years in the total amount of rain.” completely ignores that these 3 months are the key months when you try to grow plants.
https://www.monticello.org/site/research-and-collections/eruption-mount-tambora
“In September 1816, Jefferson scanned his rainfall records and considered weather reports from elsewhere as he continued to puzzle over the drastic change in weather. From his correspondence with Albert Gallatin, we read:
We have had the most extraordinary year of drought & cold ever known in the history of America. in June, instead of 3 3/4 I. our average of rain for that month, we had only 1/3 of an inch, in Aug. instead of 9 1/6 I. our average, we had only 8/10 of an inch. and it still continues. the summer too has been as cold as a moderate winter. in every state North of this there has been frost in every month of the year; in this state we had none in June & July. but those of Aug. killed much corn over the mountains. the crop of corn thro’ the Atlantic states will probably be less than 1/3 of an ordinary one, that of tob[acc]o still less, and of mean quality.4
The eruption of Mount Tambora offers only one instance of the payoff to science from Thomas Jefferson’s passion for collecting basic data on natural phenomena.”
I guess the “lesson” for “mankind” to this day is this: The annual average temps are less important, what we should care about is precipitation and temperatures during growing season.
Best,
Gerhard
Gerhard, many thanks for that full quote. I had not seen the full quote before, and I see now that Jefferson was indeed not exaggerating. Instead, he was mostly reporting the states “North of here”, with “here” being Virginia.
Also, it seems that in locations other than Monticello, in a location he calls “over the mountains”, there were frosts in August. So Monticello seems to have been a favored spot, with no frosts in the summer at all.
Thanks for the clarification, it highlights both the reality and the spotty nature of the changes.
w.
I’d be hard pressed to agree with there being frosts in July, except in various very localized places. (My father thinks he saw frozen dew in a depression off I-93 in New Hampshire one July 5th.)
In my https://wattsupwiththat.com/2016/06/05/summer-of-1816-in-new-hampshire-a-tale-of-two-freezes/ I note:
While your charts show yearly activity, one also shows monthly – the chart with first and last white frost. Since Tambora blew in April, I found it interesting that the last frost in 1815 was later than usual in the spring, occurring in mid-May 1815. How long after Tambora might the effects have been felt in Monticello? Probably a coincidence, but interesting nonetheless.