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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Maunder Minimum and Little Ice Age

To claim that the Maunder Minimum affected the Little Ice Age temperatures is to entirely miss that fact that the LIA started 300 years before the start of the MM and ended over 100 years after it. Thus they seem more coincidental than related in any way.

Maunder Minimum

The Editors's picture

Hi Keith, Very good point. We’ve edited the copy in this article to clarify. Thanks for this helpful comment. Sincerely, the OFA Editors

Pretty much kills the man

Pretty much kills the man made "climate change" hoax.

Fraudulent warming, I mean cooling, I mean climate

A little research will reveal that the cooling and warming of the earth is cyclical and the sun is the "main". it is a fact that cooling on Mars occurs with cooling on earth.. No SUV's there that I know of.. It sickens me to see these kids fresh out of college falling for this bunk. Yes, I know, I know 98% of scientist concur, but remember those are only the scientist that someone is asking and 100% of those are getting their funding to provide prove an agenda that man made climate change exist. Find those scientist that don't have to put food on the table from the cause and you'll find the truth whipper snapper. The Young lady who believes the movie "The Day after tomorrow" just makes me embarrassed for her.

Here, here!

Here, here!

BillBoy Baggins response 07 MAR 19

Good job. Stay alert and keep up the excellent work.

Reversal of earth's magnetic fields

Could weak solar minimum cause a shift in earth's magnetic fields?

reversal of earths magnetic fields

Why is the content of this field kept private and not shown to the people?

Solar sunspots

My water well drilling business was directly affected by this solar cycle in the 1980's in Johannesburg South Africa. I began drilling water wells in 1983 as the drought took hold and Southern Africa suffered a terrible drought with crops failing everywhere. I had plenty of work while there were no sunspots and no rain, but when the sunspots returned in 1987, so did the rain and that was the end of my drilling business. The area that I worked in was a summer rainfall area, not like the winter rainfall area around Cape Town. Now with low sunspot activity, the eastern half of the country has enjoyed great rain in the last 2 years, even up until the last 10 days, while the area around Cape Town has had at least 2 years of bad drought. Before the last two years there was a drought on in South Africa in the eastern half in the summer rainfall area up until 2016, which correlated nicely with the droughts every 11 years in South Africa.. Now there is more rainfall. Maybe the weather is saying that the sun spots will soon be returning, even though they are predicted to be absent until 2019/2010.

Chris Landau
Geologist/Meteorologist and amateur astronomer
April 1, 2018 5.45 pm (after April 1st midday cut off time for April Fools day jokes)
I no longer do geology or meteorology but write science fiction and short stories.

Its hot!

The last few years, summers have been relatively mild. But this summer in North CA has been brutally hot! It is 105 right now at 1:30 pm!

Little Ice Age sunspots

How did you come by the number of sunspots during this time period? Thanks

solar activity

Have I a correlation between less solar flares and the weather being colder in America and England.The cold air pushing down from Canada and Russia.slightly counterclockwise?

There were many scientists

The Editors's picture

There were many scientists who studied the Sun’s energy output though there weren’t official records. British astronomer John Herschel (1792–1871) and French physicist Claude Pouillet (1790–1868) were some of the first who invented apparatus for measurements.

sun observtions

The article states that record keeping began in 1755. So how do you know how active the sun was in the dates you mention that came before 1755. Especially for the 12th and 13th centuries?

what is the difference

what is the difference between Coronal mass , solar flaire and sunspots?

solar definitions

The Editors's picture

Please see the article above for a brief description of each. The sun is made of gases that rotate, generating magnetic field - but various sections rotate differently. Hot gases bubble and burst through the mix, tangling and looping the “lines” of the magnetic field. Sunspots, which appear to us as dark patches, are magnetic storms on the surface. They occur where these intense magnetic loops poke through the Sun’s surface. Eventually, like an overstretched rubber band, each stressed magnetic field “breaks,” releasing tremendous energy and magnetically charged gases into space. Solar flares are bursts of radiation released, including visible light and x-rays. A solar flare from the Sun can reach Earth in about 8 minutes, and can last from a few minutes to several hours. Their strength is rated according to their brightness in x-ray wavelengths. Coronal mass ejection, or CMEs, are large clouds of gases and magnetized particles (plasma) thrown out from the Sun; if oriented in the proper direction, a CME can take 1 to 3 days to reach Earth. Flares and CMEs can occur at the same time, but not always. Solar flares are localized, usually occurring near a sunspot; CMEs are much larger events, and can sometimes be larger than the Sun. Both flares and CMEs, depending on strength and orientation, etc., have the potential to disrupt communication signals (satellites, radio, etc.) and cause power grid fluctuations. Both solar flares and CMEs can cause auroras.


I got more knowledge about in the solar cycle activity.

Just read your reply to my

Just read your reply to my earlier submission on solar cycle 24. However, you were silent on a question I posed: Any geophysical explanation for the existence of more or less, two distinct pronounced peaks during this cycle. An explanation, if any, would be appreciated.

I wonder why solar cycle 24

I wonder why solar cycle 24 reached its maximum in 2014, to me that was delayed by roughly two years. The peak was expected by 2012! Or, were there two peaks in this cycle? Any explanation(s) please?

Cycle peaks

The Editors's picture

Hi, Larry,

Sunspot cycle duration is 11 years on average and typically peak, one time, in the middle of that period. Not all cycles are the same, however. Solar Cycle 24 is now well into its declining phase after reaching double peaks in late 2011 and early 2014. Despite having two maxima, this cycle is the smallest in more than 100 years, and solar activity is expected to continue to decline from these low peaks toward its expected minima in early 2019.

For a glance at Cycle 25, click here: http://science.nasa.gov/science-news/science-at-nasa/2006/10may_longrange/

Sunspot cycle and global climate

Since the lions share of energy that warms the earth comes from the sun any reduction of solar out put will cool the earth regardless of what we people do or don't do. The best thing mankind could do is get set for a moor glaciation and that includes having contingency plans for relocating nuclear fuels, waste and power stations in short order.

Very clear the explanations.

Very clear the explanations. Congratulations.

Solar Radiatons

I want to know about that

Dear Friends, Can someone

Dear Friends,

Can someone tell me what the pre-dawn northern California sky would have looked like the morning of the April 18, 1906 SF earthquake?

Was Mars unusually visible, or would there have been something else interesting in the sky?

Following a weak solar cycle, had there been a notable cooling phase?

I'd love to know anything specific. Thank you, Robin

Hi Robin,

The Editors's picture

Hi Robin,

According to our 1906 Old Farmer’s Almanac, Mars was an evening star until July 15, then it became a morning star for the rest of the year. The right-hand page for April 1906 says “Low tides” for April 18. The day before (April 17) Mercury was stationary. On the 19th, there was a conjunction of Saturn and the Moon. Last quarter Moon was on April 15 (ET). Moon runs high was on April 2; Moon runs low was on April 13. Moon at perigee on April 10; Moon at apogee on April 25. Hope this helps!

I recently came across the

I recently came across the book "Dark Winter" by John L Casey.
This book defines not only the short but the long (206 yr) cycle.
These cycles are interesting to me personalty as their results are outlined by my grandfathers as far back as the late 1600s.
I have a practical question: What will be the impact on solar panel power production as the result of a Solar Minimum?

Dark awinter

Dark Winter is an excellent book. Well researched with good documentation. I recommend it highly.

Im thinking, by observing the

Im thinking, by observing the severity of the weather where im at, i noticed, we seem to have more intense whether patterns when a significant cme has made impact with earth

There is a distinct

There is a distinct possibility that as Uranium is used up, the geomagnetic forces are being disrupted and sulfuric acid and/or phosphoric acid is splattering about the sun mainly composed of glass.

Thus, Uranium use must be reviewed in this light all around the world.

I'm not sure where you got

I'm not sure where you got your Ph.D.

The Sun is not burning uranium. It's burning Hydrogen, converting it to Helium through the fusion process.