What Are Solar Cycles, and How Do They Affect Weather?

Learn About the Sun and Its Effect on Earth's Climate

March 4, 2021
Space Weather and Solar Flares

What are solar cycles and sunspots—and what causes them? Here at The Old Farmer’s Almanac, we believe that all weather on Earth, from the surface of the planet out into space, begins with the Sun. Here’s our quick solar cycle beginner’s guide to help you understand the basics of how our Sun’s 11-year solar cycle works.

Both space weather and terrestrial (Earth) weather—the weather we feel at the surface—are influenced by the small changes the Sun undergoes during its solar cycle.

What is the Solar Cycle?

The simpliest solar cycle definition is: “The solar cycle is the cycle that the Sun’s magnetic field goes through approximately every 11 years.”

Let’s explain: Remember that the Sun is a hot ball of glowing, electrically-charged gases. The Sun’s high temperatures causes these electrically-charged gases to constantly move around, generating areas of powerful magnetic forces or fields. This motion creates a lot of activity on the Sun’s surface, called solar activity.

In areas where the magnetic fields are particularly strong, we may see a black spot—called a sunspot—emerge on the surface of the Sun. This is indicative of a sunstorm and a lot of activity beneath the surface. More sunspots means more solar activity.

There does seem to be an ebb and flow or “cycle” to this magnetic flow and movement. The total number of sunspots has long been known to vary with an approximately 11-year repetition known as the solar cycle—going from low to high and then high to low. The peak of sunspot activity is known as solar maximum and the low is known as solar minimum.

Note: The exact length of the cycle is not always 11 years; it has been as short as eight years and as long as 14.

Eleven years in the life of the Sun from 1980 (start of solar maximum) to 1986 (near minimum) to 1989 (near maximum again). Credit: NASA

Sunstorms, Flare-Ups, and Eruptions!

Our burning star may seem like it’s a constant, unchanging ball, always looking the same. However, just like planet Earth, the Sun has weather. It has giant storms! It flares up! It ejects huge bubbles of gas from the surface toward space and our planet. Here are some definitions: 

  • Sunspots indicate active magnetic fields. The dark spots are cooler than the surrounding areas. Think of them as caps to a magnetic storm that is brewing just below the solar surface. The Sun’s magnetic fields are moving around, getting twisted and concentrated in these regions. Learn more in “What Are Sunspots?”
  • Solar flares appear as flashes of light on the Sun, and are associated with sunspots. Occasionally, when powerful magnetic fields reconnect, they explode and break through the sun’s surface!  There is a sudden burst light energy and X-rays. Flares are classified according to their strength. The smallest ones are B-class, followed by C, M, and X, the largest. M-class flares can cause brief radio blackouts at the poles and minor radiation storms that might endanger astronauts.
  • Coronal mass ejections (CMEs) are massive clouds of particles that spread into space! Large pieces of magnetic energy are hurled from the Sun into interplanetary space at speeds up to several million mph. CMEs can occur when filaments/prominences become unstable and fly away from the Sun. We call this a filament/prominence eruption.
  • Other solar events include solar wind streams that come from the coronal holes on the Sun and solar energetic particles that are primarily released by CMEs.

Solar flares, CMEs, and other explosions tend to occur near sunspot groups when the Sun is more active. Naturally, all of this solar activity coincide with solar maximum.

Watch solar flares versus CMEs

Why Does the Solar Cycle Happen?

The Sun goes through these cycles due to its magnetic nature. The Sun itself has a north and a south magnetic pole.

Because the Sun’s gases are constantly moving, the magnetic materials constantly gets tangled, stretched, and twisted. Over time, these movements eventually lead to the poles reversing.

The solar cycle happens because of this pole flip! The north becomes south and south becomes north every 11 years or so.

The poles reverse again back to where they started, making the full solar cycle a 22-year phenomenon. 

How Does Solar Activity Affect Weather?

The Sun affects both weather and technology (which we’re increasingly dependent on) here on Earth. For example:

  • GPS, satellites, and other high-tech systems in space can be affected by an active Sun. Some of these systems are not protected by Earth’s atmospheric layers, so large solar flares have the potential to cause billions of dollars in damage to the world’s high-tech infrastructure—from GPS navigation to power grids to air travel to financial services.
  • Radiation hazards for astronauts can be caused by a quiet Sun. Weak solar winds allow more galactic cosmic rays into the inner solar system. Even airline pilots and crew can get a higher dose of radiation during solar storms.
  • Weather on Earth can also be affected. According to Bob Berman, astronomer for The Old Farmer’s Almanac, NOAA scientists have now concluded that four factors determine global temperatures: carbon dioxide levels, volcanic eruptions, Pacific El Niño pattern, and the Sun’s activity
  • Global climate change, including long-term periods of global cold, rainfall, drought, and other weather shifts, may also be influenced by solar cycle activity.

Painting by Abraham Hondius, “The Frozen Thames, looking Eastwards towards Old London Bridge,” 1677. Image credit: Museum of London.

The Maunder Minimum and the “Little Ice Age” 

Times of depressed solar activity seem to correspond with times of global cold in history. The most famous example is the “Little Ice Age.”

  • Between 1645 and 1715—during what we now call the “Maunder Minimum”—sunspots were exceedingly rare.
  • Specifically, there were only about 50 sunspots (instead of the usual 40 to 50 thousand) and harsh winters.
  • For 70 years, temperatures dropped by 1.8 to 2.7 degrees Fahrenheit. 
  • Seven decades of freezing weather, corresponding with the coldest period of the Little Ice Age, led to shorter seasons and ultimately food shortages.

Conversely, times of increased solar activity have corresponded with global warming. During the 12th and 13th centuries, the Sun was active, and the European climate was quite mild.

Experts do not know for certain, however, what caused the Little Ice Age; theories suggest that it was likely due to a combination of events. Some scientists are researching other factors, such as heightened volcanic activity, that corresponded with the time of the Maunder Minimum.

What Solar Cycle Are We In Now?

We are now in Solar Cycle 25. Record-keeping of solar cycles began in 1755 with Solar Cycle 1. 

In December, 2019, the sunspot numbers hit the solar minimum and “rock bottom” and the Sun passed from Cycle 24 into Cycle 25. The solar maximum or peak is predicted to happen in July, 2025.

  • By solar minimum, we mean the lowest number of sunspots. After some years of high activity, the Sun will ramp down with fewer sunspots or almost no sunspots. The temperature cools.
  • Conversely, solar maximum is the highest number of sunspots in any given cycle. A new cycle starts with a “solar maximum” littered with solar storms and sunspots. The temperature warms.

As the cycles can overlap, it can be challenging to predict when a new cycle begins. However, there are some clues. For example, sunspots tend to form nearer the Sun’s equator as the cycle winds down (and at higher latitudes when a new cycle begins). Scientists measure solar cycles by keeping track of the number of sunspots appearing on the Sun’s surface as well as noting the location. A new solar cycle is considered to have begun when sunspots group at higher latitudes with the magnetic polarities of the leading spots opposite that of the previous cycle. 

Will Solar Cycle 25 be quiet or wild? See the predictions for Solar Cycle 25.


Reader Comments

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Elements stratify by density

Elements stratify by density and if what is known on earth is applied to the sun then an assumption can be made that the lightest known elements will be on the outer surface of a celestial body and the densest at its core. Uranium and other radioactive matter are the denser elements known to man, and hydrogen is the least dense so it would make sense that the sun has a super dense radioactive core and a foamy hydrogen surface. "Science" makes conclusions about the Sun based on what radiometric spectra its surface emits... Sadly this reasoning is as profound as if one were peering down on Earth through a space telescope and determining the engine under the hood of a parked car based on the color of its paint. All that to say there may be some substance to what Mr PHD has stated.

Electrical Universe

I'm not saying Dr. Uranium is correct but you referenced hydrogen and fusion in your theory what state do you propose the hydrogen is in before and after this fusion process??

I have always believed that

I have always believed that the activity of the sun is the primary driver of our weather. Blaming CO@ is truly a scam. It is only 400 PPM overall in our atmosphere. What we do not hear is how much is man-made. Scientists tell us it is 3% of the 400 PPM. The ocean absorbs about 40% of that so that leave us with our part being 1.8%. That 1.8% of man's part is globally. Now USA only accounts for 3% of the entire globe. That means our part in the USA has to be extremely minute. Somewhere around .0005% of man=made CO2. Dang. Did you know that the biggest polluters are China and India and they are exempt from Kyoto? It would cost us billions to correct our part by only 10%. To get an additional 10% it would cost us twice as much as the 1st 10%. We cannot afford that and we wouldn't make any measurable impact on global warming at all.We are wasting our time. And by the way, the recommended level for all plant life is between 1000 and 1500 PPM of CO2 which has been proven by 1000s of studies paid for by our government. We need more CO2, not less. Marijuana growers use a level of 1200 to 1500 PPM for ideal marijuana growing in a greenhouse.The ones who push global warming are the ones who smoke the most of this weed. And they want it perfectly grown, of course. I will be so glad when the mini ice age gets here. They will have to smoke in doors and create a lot of carbon monoxide. And that would be a good thing in this case.

I like how they break it down

I like how they break it down and show some examples.

Nasa and NoAA who have been

Nasa and NoAA who have been involved in changing temp readings that are now under review. You want us to believe them. Really.

No way is the carbon 13/12

No way is the carbon 13/12 ration a scam. The upper layers of the atmosphere are not showing enough heat content to point to solar activity as a major source of climate disruption. PLEASE read the NASA and IPCC reports. Forced global warming is real.

With the earth's continual

With the earth's continual global warming I believe the movie "The Day After Tommorrow" is in line with what is actually occurring now! The oceon is getting warmer and warmer and it is the barameter of our weather and if it is effected much more it will certainly trigger a mini ice age which the earth did have several hundred years ago for about 500 years that killed a lot of people.

Be careful of believing in

Be careful of believing in Hollywood End Of The World As We Know It disaster movies.
So... Gorebull Warming causes Global Cooling and and ice age. Okay....

As it gets warmer....it's going to get cooler. Makes sense to me.... ha, ha, ha

Please Stop

"The day after tomorrow" ? Really? and warming = cooling? ... I'm embarrassed for you.

Sun spots..no sun spots what

Sun spots..no sun spots what does it all mean in layman terms! First it was global warming and now its a mini ice age!Who is right??

That it is okay globe warming

That it is okay globe warming is true so that is what I think about that

Would a solar grid on earth

Would a solar grid on earth fare differently because of dc power than ac power?

I have discovered a striking

I have discovered a striking similarity between solar cycle' sets 1 - 6 and 20 - 24. At the time I am typing this we are at solar maximum in cycle 24 and it is strikingly obvious now that we are heading into a cooling trend not seen since the Dalton minimum. Take the two graph sets I mentioned and put one on top of the other to see for your self. Absolutely Ironic!

Is there any correlation

Is there any correlation between the quiet solar maximum (fewer solar flares than normal) in 2014 and the solar pole shift December 31, 2013?

Yes, P Bee.There is a direct

The Editors's picture

Yes, P Bee.There is a direct correlation. The solar magnetic reversals occur close to, some say "at," the solar maximum. Here is more information:

My father was an

My father was an astronautical research scientist for 60 years -inventing materials that would protect the space shuttle from burning up and freezing on it's voyage. Dinner conversation revolved around the facts of the solar flares and other space activity and their affect on the warming and cooling of the earth. It was the later part of the cold war days, so much of his research was secret, but surely NASA is able to make public the details of all of the years of research which explain in scientific terms the sun's afftects on our weather. Somehow we seem to only refer to the immediate lower atmosphere and neglect the giant weather maker in the sky! Someone needs to say " look up ,stupid, it's the sun!" Keep it simple, maybe people will begin to understand real science again.

I am doing a research paper

I am doing a research paper on the subject of the facts and myths behind climate change. I purchased a great book recently called, "The Cooling Stars" that speaks in detail over the sun's impact over our climate. When CME's decreases due to diminishing number of sunpots, this condition allows CGRs from space to ionize our atmosphere to enhance cloud formation. The more clouds there are the less light reachers the earth to cause radiative heating to occur. The converse is true too.


Thanks for sharing, Kwits. We

The Editors's picture

Thanks for sharing, Kwits. We addressed this is in the 2009 Almanac as a color-page feature.

We are headed into another

We are headed into another ice age. NOAA 10,000 year ice core analysis shows the subtle but incontrovertible evidence that we are sliding into a cold cycle that will establish a new ice age. The little "blip" of our AGW fantasy is just that, a little blip. See for yourself:



AGW may make you a little warmer and you may loose that beachfront house, but global cooling will starve you.

Yes I Observed a trend to

Yes I Observed a trend to cooler temps in the past decade and could see global warming should be off because of refletive properties of the atmospher in tandum w/ an assumtion tnat the sun is on an eliptical excuse me I mean the earth is on an eliptical orbit of sol , But! I am not sure where we are at this point moving farther away or closer? If I remember rightly it takes what ? 100,000 years to complete? Is there any effect occuring from this? Thank you

I am wondering where I can

I am wondering where I can find sun activity for a given month in terms I can understand. I am trying to find a pattern with my young son's behavior. Lunar has not proven any correlation and I am wondering about solar.

what about his diet? might

what about his diet? might want to start there

Who was counting Suns Spots

Who was counting Suns Spots in 1610? What sort of clarity would the elescope they use have? And what condition would their eyes be in after staring into the sun without any modern protection?

My work with Tellurics on buried pipelines suggests that Sun Spot activity and it's effect on the magnetic field of the earth is a more recent discovery.

Pipeline Guy, According to

Pipeline Guy,

According to the NASA/Marshall site:


"In 1610, shortly after viewing the sun with his new telescope, Galileo Galilei (or was it Thomas Harriot?) made the first European observations of Sunspots. Continuous daily observations were started at the Zurich Observatory in 1849 and earlier observations have been used to extend the records back to 1610."


space weather changes are based of sun activities

i am Mohammed i work as Researcher in Institute of Space Research and Aerospace(ISRA) Khartoum - Sudan
i want data for sunspots and sun activities from (2012 to 2017) and the suitable tools which use to it. and how can i do that? I need the method of analysis and the best models or statistic correlations.
hope to hear from you soon.

with hot regards

I posted this on my Facebook

I posted this on my Facebook page(Notes)

I do not see a date (year) on this article.

When did this occur, "Recently (201x?), NOAA scientists finally concluded that four factors determined global temperatures: carbon dioxide levels, volcanic eruptions, Pacific El Niño pattern, and the Sun's activity. "

Hi, Daniel, We consulted Bob

The Editors's picture

Hi, Daniel,

We consulted Bob Berman about the article that you cite from the Times Union. Here is his response:

It's all in my book, The Sun's Heartbeat -- now out in paperback. All the credits, and the people at NOAA who have come to this conclusion, and told me so in person during my research visits there, and the evidence behind it.
Best, Bob

Daniel, FYI, the book was published in 2011.

In looking further, we found an explanation on this page (http://oceanservice.noaa.gov/e... ), which, at the bottom, cites its date as 2007.

We provide the link above to shed light on your question. More information can be found by searching the Web using relevant key words.

We hope this helps.

Thanks for your response. I

Thanks for your response.

I just viewed your response (blog illiterate)

I believe the illusion is the flares must be large and have CMS's. I do not believe that. I do believe the cumulative effect of unidentified element "zzz" within M and X flares over a period of time has a cumulative effect on "attracted" protective atmospheric gases toward the sun-side of the earth, thus exposing the shadow-side to -350 temperature through transference. Thus the early freezes this Winter/Fall.

For the past five years, I have google weekly searched terms: “’solar flare’ climate” and have never seen this NASA article, TIMELY???? "SABER is cataloging the atmospheric response to solar forcing and is providing a solid baseline for examining long-term changes in the climatology of the upper atmosphere."

NASA Measures Impact of Huge Solar Flare on Earth's Atmosphere

"We don't know yet how these affect weather or climate -- likely there is not any direct effect," he said, "but there may be, over time, influences on ozone that affect climate."

"These results are very timely," said James Russell, SABER's principal investigator at Hampton University in Hampton, Va. "SABER is cataloging the atmospheric response to solar forcing and is providing a solid baseline for examining long-term changes in the climatology of the upper atmosphere."

The dates are listed

The dates are listed throughout the article. The picture at the top is of the 2013 almanac, which means this information is from this years almanac. Also the article talks about August 2013... Which means the article was written between now and then. This has been happening all along. El Nino is an annual occurrence, but according to the patterns it is catastrophic every 7 years. It just so happens that this 11th year cycle of the sunspots, and the 7th year el Nino, are occurring in the same year. This can only mean worldwide disasters.