The greatest geomagnetic storm of the 20th Century…May 13-15, 1921…a century ago, New York City/New York State were especially hard hit

Paul Dorian

A powerful solar storm in May 1921 had major impacts on Earth ranging from fires at telegraph stations and railroad facilities to the disruption of telephone lines and radio broadcasts to the knocking out of telegraph lines across the United States and Europe. Because many problems took place near New York’s Grand Central Terminal, the storm is sometimes referred to as the “New York Railroad Storm”. (Credit: background image- NASA/SDO, headlines- StarDate).

*The greatest geomagnetic storm of the 20th Century…May 13-15, 1921…a century ago, New York City/New York State were especially hard hit*


The most intense geomagnetic storm of the 20th Century took place during solar cycle 15 in a 3-day period from May 13-15 in 1921.  The storm occurred before the widespread electrical dependence of infrastructure that we have in today’s world, but the impact from an extraordinarily powerful coronal mass ejection was still quite extensive.  The storm’s electrical current sparked a number of fires around the world including one near the Grand Central Terminal in New York City. In addition, auroras appeared throughout the eastern US creating brightly lit nighttime skies and telegraph service virtually stopped in its tracks due to blown fuses and damaged equipment. Research in recent years has suggested that this super solar storm of May 1921 was equally as intense as the granddaddy of all super storms in recorded history – the “Carrington Event of 1859”.

Sunspot region now referred to as “AR1842” as it was recorded on May 13, 1921. Courtesy

Gigantic sunspot

The biggest solar storm of the 20th Century actually took place during the declining phase of solar cycle #15 with the culprit being a gigantic sunspot that was referred to then as “Greenwich region 933404”.   This sunspot was first seen on the sun’s east limb on May 8th, 1921 and it rotated to the west limb over the next ten days or so. This sunspot likely produced as many as six coronal mass ejections (CMEs) directly toward Earth during this time period as registered in ground-based magnetometer measurements (Newton, 1948, p. 178).  Scientists around the world were surprised and likely quite amazed when their magnetometers went “off the scales” in the peak part of the storm during the May 13-15 time period. Little did they know that this would turn out to be the biggest solar storm of the century – and there has been nothing quite like it ever since according to Dr. Tony Phillips of 

Impact was especially intense in New York City/New York State

The impact of the super solar storm of May 1921 was especially acute in New York City and across New York State and this is why this event is sometimes referred to as the “New York Railroad Superstorm” (Love, et al, 2019). Electrical currents induced by geomagnetic activity surged through telephone and telegraph lines, heating them to the point of combustion. The railroad control tower near New York City’s Grand Central Station broke out in flames.  Flames also engulfed the switch-board just north of New York City at the Brewster station of the Central New England railroad and spread enough to destroy the entire building.  A telegraph operator there was driven from his keys by “electric fluid” that suddenly “flared out” (The Bridgeport Telegram, 17 May 1921, p. 11).  On May 14th, excessive electric currents on telephone lines caused the Union Railroad Station in Albany, NY to catch fire and the station burned to the ground. The New York Times reported that storm-related effects were particularly pronounced throughout the eastern US where fluctuating electric currents grew to a level where “hardly a wire was working anywhere” and stray voltages on some wires exceeded 1000 V. Auroras over New York City were apparently so bright that even the “intense lights of the electric signs along Broadway could not dim the brilliance of the flaring skies” (The New York Times, 15 May 1921, p. 1; 17 May 1921, p. 1).

Headlines from the great solar storm of May 1921 (courtesy

The impact of the super solar storm spread around the world with fires erupting in numerous places including, for example, a telegraph exchange in Sweden that burst into flames on May 15th.  There were disruptions to telegraph systems in Australia, Brazil, Denmark, France, Japan, New Zealand, Norway, Sweden, and the UK.  At the peak of the storm, “northern lights” were seen as far south as Texas in the US, by ships at sea crossing the equator, and even in the southern hemisphere in places like Samoa and Tonga.

Daily observations of the number of sunspots since 1 January 1900 according to Solar Influences Data Analysis Center (SIDC). The thin blue line indicates the daily sunspot number, while the dark blue line indicates the running annual average. The arrow indicates the time period of the May 1921 super storm which occurred during the declining phase of solar cycle #15. (Plot courtesy

Interesting impact on radio propagation

One of the interesting features of this solar storm according to a recent publication (Hapgood, 2019) was its variable impact on the propagation of long distance radio signals. There were reports showing both disruption and enhancement of radio propagation, with reports of enhancement gaining much attention because they were in stark contrast to the disruption of other telecommunications systems. One example of enhancement was a report in the New York Times (NYT, 1921a) that radio signals reaching New York from Berlin (some 6,400 km distant) and Bordeaux (5,800 km) were much stronger than usual between 02:30 and 04:00 GMT on 15 May. This report has particular credibility because the New York Times was one of a number of U.S. newspapers that then operated their own radio stations to receive news from Europe (Hudson et al., 2000). The good performance of radio links in the United States and at Bordeaux was also confirmed in statements by the Radio Corporation of America (Telegraph and Telephone Age, 1921b). Another example of enhancement came from the Pacific region, where Angenheister and Westland (1921a) and Gibbs (1921) reported unusually good conditions around 06:15 on radio links between radio stations at Apia in Samoa and Awanui in the north of New Zealand (a distance of 2,700 km).

To understand the enhancement of radio signals during the storm, it is essential to appreciate that the radio systems in use in 1921 operated in low‐frequency radio bands below 300 kHz. For example, the radio link between New Zealand and Samoa operated at 150 kHz (Gibbs, 1921). At this frequency, radio signals couple to the conductive surface of the Earth, both land and sea, and propagate along that surface, following the curvature of the Earth in a so‐called “ground wave.” The signals are gradually attenuated by the finite conductivity of the surface with less attenuation where conductivity is higher, mostly obviously over the salt water that forms the oceans (International Telecommunications Union, 2007). However, the signals can also propagate into the upper atmosphere and be reflected from the ionosphere giving a “sky wave” that can interfere with the ground wave signal, causing problems with signal reception. Sky wave interference can also arise from distant sources of natural radio signals such as lightning and other electrical activity in the atmosphere. Thus, good conditions for signal propagation at 150 kHz will arise when sky waves are heavily attenuated by absorption due to significant plasma density in the lower ionosphere below 90 km (credit Hapgood, 2019).

Potential impact on today’s world

Some recent research (e.g., Love, et al, 2019) now suggests that this great solar storm of May 1921 was about as equally intense as the “Carrington Event of 1859” which has been dubbed the strongest solar storm in recorded history. The super solar storm of 1859 took place during solar cycle #10 and was named for the British astronomer, Richard Carrington, as he observed from his own private observatory the solar flare which caused a major coronal mass ejection (CME) to travel directly toward Earth. Perhaps the most intense storm since the May 1921 super storm was the magnetic storm of March 1989 which caused an electricity blackout in Quebec, Canada.  

In today’s world, electronic technologies have become embedded into everyday life and are, of course, quite vulnerable to solar activity. Power lines, long-distance telephone cables, radar, cell phones, GPS, and satellites – all of which could be significantly affected by an event like the one of 1859 or the storm of 1921.  In other words, the world’s high-tech infrastructure could grind to a halt disrupting daily activities from purchasing a gallon gas to using the Internet.

Of particular concern is the fear about what this kind of solar storm could do to the electrical grid since power surges caused by solar particles can blow out giant transformers.  If numerous transformers happened to be destroyed at once, it would likely take a painfully long time to replace them.  The eastern US is especially vulnerable since the power infrastructure is highly interconnected so that failures in one location could cause failures in other regions. One long-term solution to this vulnerability would be to rebuild the aging power grid to be less susceptible to solar disruptions.

On the positive side, there is comfort in the fact that observations of the sun in today’s world are a constant with a fleet of spacecraft in position to monitor the sun and gather data on solar flares. Also, there is better forecasting today and solar scientists could give some sort of warning as to when solar flares might appear and whether a given storm is pointed at Earth.  Improved forecasting can allow for mitigating actions to be taken since the most damaging emissions travel slowly enough to be detected by satellites well before the particles strike the Earth.  For example, power companies could protect valuable transformers by taking them offline before a solar storm strikes.

One thing is certain, we should be prepared for another massive solar storm of the magnitude of the “Carrington Event of 1859” or the great geomagnetic storm of May 1921 – the most powerful solar storm of the 20th century.

Meteorologist Paul Dorian


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May 13, 2021 6:06 pm

If anyone can make it happen, Joe can.

Reply to  Scissor
May 13, 2021 6:28 pm

No, it will be Trump’s fault.

Gary K Hoffman
Reply to  Philip
May 14, 2021 2:09 pm

Women, minorities hardest hit.

Reply to  Scissor
May 14, 2021 7:53 am

That made me laugh!

And on a more serious note, this is a real time bomb, that science is well aware of, that will recur sooner or later. Yet, we are spending billions studying and mitigating an atmospheric trace gas instead of preparing the world for something that is statistically imminent. We just saw what happened when a single pipeline went down, so can you imagine what a repeat of the Carrington Event will do? This is the real Inconvenient Truth. (sigh)

Smart Rock
May 13, 2021 6:18 pm

If we get another one, the Guardian will tell us it’s further evidence of climate change. /s

Alan the Brit
Reply to  Smart Rock
May 13, 2021 11:10 pm

As yet again I’ve said before, around 15-20 years ago the BBC Horizon show made a fascinating programme on the Sun, with fantastic video footage of its activity. They ended the prog by the halfwit narrator (a mere actor, they aren’t renown for their scientiffcky astuteness!) saying, “No one can fully explain what effect the power of the Sun has on the Earth’s climate, but whatever it is, it’s already been overtaken by manmade climate change!!!!” And as previously noted, the statement was clear that “We don’t know what effect element ‘A’ has upon element ‘B’, but we know for a fact, element ‘C’ overpowers element ‘A’!!!” The most ridiculously unscientific statement I have ever heard!!! Now a retired structural engineer, I was always taught that if I didn’t know the answer, never to pretend that I did, & don’t make it up, as it’s unprofessional, & such mis-directions have a habit of coming back & biting you where it could really hurt!!!! Clearly climate scientificky peeps tend not to possess such qualities!!! Shame!

Jim Whelan
Reply to  Alan the Brit
May 14, 2021 8:00 am

In today’s world it’s believed that “science” has the answers. To say you don’t know is “unscientific”.

Reply to  Smart Rock
May 14, 2021 5:19 am

last night aus time Im pretty sure it was science alert page I saw but didnt read cos I was SO annoyed, and now its vanished
a report that CC is making the entire planets upper atmosphere SHRINK by 380 or more km
that was the preread schtick..
its utterly gone and cant find it at SOTT either and the tend to run SA items like that too

the small fact that the solar magnetics affects OURS seems to have been ignored

Reply to  Smart Rock
May 14, 2021 6:34 am

@smart rock. Why don’t I see the sarcasm in your statement.

Walter Horsting
May 13, 2021 6:51 pm

Being in California, I can see millions of roof tp solar panels fires…

Reply to  Walter Horsting
May 14, 2021 3:33 am

What about all lithium fires that can not be put out in the variety storage batteries including Tesla cars?

Larry in Texas
Reply to  Vuk
May 14, 2021 9:25 am

OMG! Glad I don’t own a Tesla, having read about such a fire (I think it was on this website) occurring after a self-driving Tesla crashed in Houston.

Reply to  Larry in Texas
May 14, 2021 9:49 am

Sudden voltage/current surge on the greed while car is on the charge may cause short circuit and fire within any one of 2170 cells in model 3 or up to 7100 in model S. More cells more risk of one cell short-circuiting and whole lot going up in flames. More cells bigger and I suppose more intense fire while effect on solar panels may be negligible and as in many domestic appliances electronics will just go dead and unlikely to cause fire.

Reply to  Vuk
May 14, 2021 11:02 am

the spellchecker prefers ‘greed’ to ‘grid’.

Tom Abbott
Reply to  Larry in Texas
May 15, 2021 3:28 am

“OMG! Glad I don’t own a Tesla”

I read an article last night that decribed a Tesla owner and his problems with the car.

It seems he left his Tesla to charge for an extended period of time and this caused an unfortunate situation.

According to the owner, the Tesla has two batteries. One is the large battery pack that is used to power the car, and then there is a conventional 12-volt battery that runs most of the accessories of the car.

When he left the Tesla for an extended period of time, the battery charger eventually recharged the big battery pack, but it does nothing to keep the little 12-volt battery charged, and this guy did not drive the car long enough that the little 12-volt battery ran out of juice.

When the little battery runs out of juice, you can’t open the doors of the Tesla or the trunk and you end up having to remove body parts of the car to get to the little battery to recharge it!

I think this guy has discovered a design flaw in the Tesla. 🙂

Tom Abbott
Reply to  Walter Horsting
May 14, 2021 3:40 am

There’s a thought.

Ron Long
May 13, 2021 6:59 pm

I’m guessing you can get an instant sun tan from these kinds of events. Wait for it.

May 13, 2021 7:19 pm

The issue for power transmission is the high inductive currents created in the long lines. The transformers all get fried, and there will be a world shortage. A year without a transmission system won’t be fun, so a bit of warning could go a long way.

Craig from Oz
Reply to  HAS
May 13, 2021 8:02 pm

Just casually discussed transformers with someone here at the Day Job who is a bit more hand on with this equipment.

He suggested that the current lead time for a transformer is 16 weeks.

So that is 16 weeks under ‘normal’ conditions.

Reply to  Craig from Oz
May 14, 2021 5:21 am

and if the global main producer was the spot that got hit also?
ie china
kiss society goodbye in a lot of places

Zig Zag Wanderer
Reply to  HAS
May 13, 2021 10:15 pm

Yup. How many backups of those house-sized transformers are there? A handful at best.

Well have a blackout for weeks. No refrigeration. No transport, perhaps? No food in the supermarkets.

We’re only 3 meals away from barbarism, apparently. We’re ok where we are, plenty of cows and guns, but the city folk will be wanting a share….

Reply to  Zig Zag Wanderer
May 13, 2021 11:06 pm

The US keeps a strategic supply of power transformers, even then a regional hit could make a decent earthquake look like a pianola (if you follow my parlance)

Reply to  Zig Zag Wanderer
May 14, 2021 12:00 am

Are the cows good shots?


Juan Slayton
Reply to  tonyb
May 14, 2021 7:46 am

Tony, we Yankees have years of experience with cows and guns. This is embedded in our national literature:

I was armed to the teeth with a pitiful little Smith & Wesson’s seven-shooter, which carried a ball like a homoeopathic pill, and it took the whole seven to make a dose for an adult. But I thought it was grand. It appeared to me to be a dangerous weapon. It only had one fault—you could not hit anything with it. One of our “conductors” practiced awhile on a cow with it, and as long as she stood still and behaved herself she was safe; but as soon as she went to moving about, and he got to shooting at other things, she came to grief.
–Mark Twain in
Roughing It

Reply to  Zig Zag Wanderer
May 14, 2021 4:32 am

Even if ny generator is a crap out we have substantial stores of canned and dry goods and steady water supply. Being rural, its not just a lifestyle choice, it is strategery!

Joel O'Bryan
May 13, 2021 7:23 pm

Near the trailing spot is probably a region of polarity intermixing, a “beta gamma delta” region per Mt Wilson classification. A bgd region, if sufficently large and active, result in magnetic reconnection events of the filaments loops between + and – spots which results in the release of blasts of contained magnetic filament energy in the plasma into the coronasphere, like many thousands of thermonuclear explosions gong off at once. This energy blast pushes matter (plasma) very fast (a CME) outwards and heats the corona-sphere very rapidly to produce an multi-million degree XRay and visible wavelengths flash.

In today’s nomenclature for characterizing ARs (the 3 component McIntosh classification (McIntosh, Sol. Phys. 125, 251-267,1990)), that trailing spot region in including the total area of the AR with leader spot, would probably be classified “FKC,” or maybe “EKC.” Without modern day magnetogram Solar images it is difficult to say for sure. Someone with high skill and experience at these AR classifications like Jan Alvestad would know better than me. Jan regularly correctly corrects the “solar experts” at NOAA/SWPC on AR classfications.

The guide to AR classifications decoder is here:

Screen Shot 2021-05-13 at 9.08.42 PM.png
May 13, 2021 9:52 pm

The effects of a major solar storm being pretty much the same as nuclear EMP, the right preparations would be the close to the same. But since there is not yet, barely, a fascist dictatorship in place in the U.S., it is unlikely to happen, and that is probably, in fact, a good thing.
People have never built to prepare for 1% could-happen sorts of disasters. At this rate, on this course, we won’t become wealthy enough to do so in this century.
People do build to prepare for 1% may-happen-again events. But even though we have two recent historical events to review, the current dependence on communications and energy delivery infrastructure did not yet exist, so nothing learned. We seem bent on erasing the history before 1980, anyway, so what’s to learn?
Factual, reasonable, and informative as this article is, it is not at all helpful or useful. “Be prepared” without practical and economical, likely recommendations are essential. I don’t know anything much more practical than individual survivalist or prepper sort of preparation, and little that whoever the author suggests he means by “we” could undertake as an any-sized group.
But we could always vote the current bums out, and then see if we could find even slightly smarter bums to replace them. In fact, it is required.
And dump the grid — it is the greatest vulnerability.

May 13, 2021 10:44 pm

“One thing is certain, we should be prepared for another massive solar storm of the magnitude of the “Carrington Event of 1859” ……”
Another certainty is that we should prepare for another big freeze when all of the windmills freeze up and the fields of solar panels are covered with ice and snow. However our current world “leaders” are all planning to shut down any coal or nuclear power stations and that will ensure that most of us will die from cold or starvation. Is this what it will take to prove that CO2 induced global warming is a Lie?

Reply to  Bevan Dockery
May 14, 2021 12:07 am

This subject comes up with astonishing regularity then gets forgotten so whether any lessons are learnt as regards preparation is doubtful.

However, for a Carrington event read ‘deliberate sabotage by unfriendly powers’. Our infrastructure is extremely vulnerable thanks to the internet and a combined attack on banking, electricity, food supplies, energy, water and communications, or perhaps only 2 out of the six, will finish off modern society very quickly.

In an age when even fridges can be connected to the internet the chances of unfriendly intervention through hacking is much greater than a Carrington event


Gerald the Mole
Reply to  tonyb
May 14, 2021 2:45 am

I hope that there is a stock of spark transmitters and crystal sets along with morse code skills

Reply to  tonyb
May 14, 2021 5:24 am

as your pipeline co and the irish govt health depts just found out via ransomeware

Bill Parsons
Reply to  tonyb
May 14, 2021 11:14 pm

A Carrington-style event might do upwards of 3 trillion dollars in damage in the U.S.
But it’s random. Though we’re made vulnerable by our “connectivity” with others, the sun has no malice. A cme can go in any direction. Whereas criminals’ use of the wired world is targeted …
“Cybercrime To Cost The World $10.5 Trillion Annually By 2025”

Tom Abbott
May 14, 2021 3:49 am

There was a federal EMP commission held about a year ago that found that it would cost the U.S. about $3 billion dollars to build replacement hardware, to be placed on standby, for the U.S. electrical grid that could be harmed by an EMP blast from the Sun or from Earthly enemies.

It could take a year or more to replace burnt out electrical equipment if we start from scratch after a major EMP event.

We can’t afford to wait that long. We should implement the commission’s findings as soon as possible, and we have all sorts of infrastructure bills in Congress now attempting to spend $Trillions of dollars, and there’s no reason why we can’t include $3 billion for electrical grid safety.

If our electrical system goes down for any length of time, we are talking about huge numbers of dead people as a result. Our politicians need to wake up to reality.

Paul S.
Reply to  Tom Abbott
May 14, 2021 7:14 am

Three billion is pocket change compared to the trillions congress is planning to spend on infrastructure. Do you suppose they consider the electric grid as infrastructure?

Reply to  Paul S.
May 14, 2021 9:46 am

The “infrastructure” they want to spend all that on is stuff like daycare from what I heard. So not so much anything with the grid.

May 14, 2021 4:30 am

So, the generator sitting in my basement not hooked up or ready to kick on automatically is still a good idea. 100 gallons of gas should allow us to keep the freezers and refrigerator cold for a couple of months. Better up my fuel storage, pronto!

Doug Huffman
Reply to  2hotel9
May 14, 2021 4:55 am

Why would not the metal in your generator be fried as well as a power line?

Here in Lake Michigan and 10^19 milliliter of potable water, the. only household infrastructure dependent on mains power is the deep well pump.

I wonder if the metal propane tank will explode too?

If it was easy then everyone might do it – physics.

Reply to  Doug Huffman
May 14, 2021 6:30 am

You really believe a generator with not running will explode? If that is true we will all die no matter what. Hell, by your reasoning we all died in 1859 so why worry. I would feel bad for you but I am too busy laughing at you. According to you all the backup equipment in storage for such events as this will be destroyed, too. Really? Sit and think for a minute, it will be good for you.

Carl Friis-Hansen
Reply to  Doug Huffman
May 14, 2021 10:05 am

The voltage and current is dependent on the strength of the field and the length of the conductor.

So in practical terms I believe it will mainly be the long supply wires, that causes problems.

Reply to  2hotel9
May 14, 2021 5:26 am

dunno bout usa petrol but Aussie stuff loses its oomph in a few months of storage
diesels wiser

Reply to  ozspeaksup
May 14, 2021 6:41 am

We buy gasoline without ethanol in it, then add StaBil. Through the summer months I rotate the older gas for use in tractors and pushmowers and string line trimmers, plus when price is down I will use several cans in vehicles and get new. As we stand now I have 100 gals at my place, another 80 at my son’s place and several friends who do much the same. I don’t have any diesel equipment, two of my neighbors are OTR truck drivers and have large storage tanks for their trucks and tractors(they farm, too), so we as a group are pretty well set.

Reply to  2hotel9
May 15, 2021 2:19 pm

Try Startron for fuel storage. I have found better results with that than Stabil.

Reply to  Ray
May 17, 2021 6:25 am

I’ll check that out. Have only had issues with blended ethanol/gasoline, turns to a jelly like, orange gatorade colored goop.

May 14, 2021 4:49 am

With our weaker Earth’s magnetic field, it may not take a big CME or two to cause major damage. The last little one we just experienced surprised everyone in the business by its effect. CME’s cause not only electrical grid problems, but raises the possibility of major geologic events and can even effect your health if you have cardio problems for example.

Personally I think the possibility of a major crisis here on Earth as the Sun ramps up this cycle is pretty high. The Colonial Pipeline issue is a precursor to how quickly we can go from normal to panic mode.

Reply to  rbabcock
May 14, 2021 9:47 am

I think the pipeline issue shows that we go to panic mode a lot faster than we used to.

Jim Whelan
Reply to  TonyG
May 14, 2021 9:52 am

Current politics and influence is almost entirely based on fear from the population killing pandemic to the existential threatening climate change fear motivates voters more than any other emotion and certainly more than logic and reason. We have been conditioned to react.

May 14, 2021 7:58 am

All of these destructive events can be estimated to happen….a super volcano every 5000 years on average?….a major asteroid hit per century?….an ice age every…..a massive tidal wave….

Patrick MJD
May 15, 2021 2:18 am

Even though shielding on electrical devices and systems from these sorts of events is better now, one thing is guaranteed, it will happen again.

Patrick H.
May 15, 2021 12:33 pm

A Carrington event today would wipe out distribution transformers. My understanding is the power companies don’t stockpile the mega transformers in our distribution systems. But they would be glad to if the tax payers payed for it. It takes two years to build those mega transformers. (I’ve been told) After two years without power the world would be a different place. I don’t think there would be a need to turn the power back on.

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