How Does the Solar Cycle Affect Weather?

Plus Forecasts for Solar Minimums and Maximums

July 11, 2019
Space Weather and Solar Flares

Here at the Almanac, we have long believed that the Sun’s weather cycles—called “solar cycles” or “sunspot cycles“—influence weather patterns here on Earth. What causes a solar cycle? Which solar cycle are we in? Are we in a solar minimum or maximum? Get the update on your Sun—updated regularly!

All weather on Earth, from the surface of the planet out into space, begins with the Sun. Both space weather and terrestrial weather (the weather we feel at the surface) are influenced by the small changes the Sun undergoes during its solar cycle—referred to as “solar activity.”

What is Solar Activity?

Our burning star may seem like it’s a constant ball, always looking the same. However, just like planet Earth, the Sun has weather. It has storms. And its storms can affect Earth’s weather. Here are a few features:

  • Sunspots are dark, cool spots on the Sun. 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.

See the Difference Between Solar Flares and CMEs

How Does Solar Activity Affect Earth?

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.

What is a Solar Cycle?

Traditionally, the number of sunspots (storms on the Sun) increase and decrease over time in a regular, approximately 11-year cycle, called the solar cycle or sunspot cycle.

Scientists measure solar cycles by keeping track of the number of sunspots appearing on its surface.

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

Record-keeping of solar cycles began in 1755. We are now nearing the end of Solar Cycle 24, approaching the solar minimum.

  • 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 equator as the cycle winds down (and at higher latitudes when a new cycle begins). 

    The Maunder Minimum or “Little Ice Age” 

    Times of depressed solar activity seem to correspond with times of global cold.

    • For example, 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 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.

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

    Current Solar Cycle 24

    Solar Cycle 24 has been one of the quietest, weakest cycles in a century and is wrapping to an end. (The prior cycle 23 also had an extended period of very few sunspots.)

    Here’s a very brief history of Cycle 24 (which we’ve been watching since it began in 2008—two years late!).

    Spotless Days (As of July, 2019)
    2019 total: 121 days (63%)
    2018 total: 221 days (61%)
    2017 total: 104 days (28%)
    2016 total: 32 days (9%) 
    2015 total: 0 days (0%) 
    2014 total: 1 day (<1%)
    2013 total: 0 days (0%)
    2012 total: 0 days (0%)
    2011 total: 2 days (<1%)
    2010 total: 51 days (14%)
    2009 total: 260 days (71%)
    2008 total: 268 days (73%) 
    2007 total: 152 days (42%)
    2006 total: 70 days (19%)

    • Cycle 24 began in early 2008, specifically January 4th.

    • In 2011, sunspots started to build again. A monthly spike occurred in November 2011. 

    • In early 2012, the smoothed sunspot number reached a first peak of 98.3 (March, 2012).

    • But early 2014 brought a second peak. The smoothed sunspot number reached a second peak of 116.4 (April, 2014). This became the official maximum.  It’s not unusual to have a double peak, but it’s rare that the second peak is larger than the first.  Cycle 24’s peak still ranks as the weakest since Cycle 14, which peaked in 1906.

    • From 2015 to 2017, sunspots kept dropping steadily from 0% spotless days in 2015 to 28% spotless days in 2017.

    • In 2018, 61% of the days were spotless! We went weeks at a time without a single spot on the Sun’s face. 

    • As of July 11, 2019, 63% of the days have been spotless—similar to an entire decade ago! 


    Start of Solar Cycle 25?

    According to forecasts, the solar minimum should begin between 2019 and 2020.

    Cycle 24 does indeed appear close to the end of its lifespan. With the total lack of sunspot activity, the Solar Minimum may be underway now.

    • On July 2, reported: “This week, a cluster of small sunspots from the next solar cycle bubbled up to the surface of the sun. The dark cores didn’t last long, but they had the unmistakable magnetic signature of Solar Cycle 25.:

    • On July 8, it was reported that a reversed-polarity sunspot has broken through the surface of the sun (the second time this month). This latest “backwards sunspot” could mark the official beginning of new Solar Cycle 25. 


    Credit: NOAA/SWPC

    Supporting this theory, the Earth’s upper atmosphere has started to cool. Data from NASA’s TIMED satellite show that the thermosphere (the uppermost layer of air around our planet) shows that “We see a cooling trend,” says Martin Mlynczak of NASA’s Langley Research Center. “High above Earth’s surface, near the edge of space, our atmosphere is losing heat energy. If current trends continue, it could soon set a Space Age record for cold.”

    In addition, the low solar energy has resulted in increased radiation, as measured by high-altitude balloons above the U.S.  Cosmic rays can alter the flow of electricity through Earth’s atmosphere, trigger lightning, potentially alter cloud cover, and affect aeronautical and airline travelers.

    Image: The TIMED satellite monitoring the temperature of the upper atmosphere.

    If this Solar Minimum is as similar to the 2008 one as it appears, the Sun dimmed by 0.1%; Earth’s upper atmosphere collapsed, allowing space junk to accumulate; solar wind slowed down so cosmic rays (normally repelled by solar wind) surged to Space Age highs.

    Much of this is the normal ebb and flow of the Sun/Earth relationship which can be stormy. That said, if the Sun goes through a more prolonged solar minimum, then Earth could experience a cold period. 

    Will the next sunspot cycle be more “normal” or will we again see a decreased number of spots?

    It’s early days. Some scientists suggest cycle 25 will be even weaker than 24.  Others expect cycle 25 to be stronger, peaking in 2024. 

    Prospects of Mini-Ice Age

    Could a deep, long-lasting solar minimum lead to extreme cold such as a mini-ice age?

    Overall, quiet-to-average cycles, such as Cycle 24, and a solar minimum phase normally mean a cooling pattern. In other words, temperatures become colder than they would have been otherwise. Sunspots are similar to a bathtub of lukewarm water; if you trickle in cold or hot water, it may take a while to notice the difference.

    If this cooling phase on Earth, however, is offset by any warming caused by increasing greenhouse gases, it also raises the question of whether an eventual warming cycle could lead to more rapid warming on Earth than expected.

    According to solar radiation expert Judith Lean, PhD, of the Naval Research Laboratory, if we do have a “Maunder Minimum,” it would not be a return to the “Little Ice Age.” She points to a current global surface temperature that’s about 1.8 degrees Fahrenheit, warmer than at the time of the Maunder Minimum and says that a return to a Maunder Minimum phenomenon would lead to a cooling by only one-tenth of a degree C or 0.18 degree F.

    In other words, a mini-ice age is doubtful. 


    Stay tuned for further updates! Want to learn more about weather and space? Pick up your copy of The Old Farmer’s Almanac!


    Reader Comments

    Leave a Comment

    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

    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

    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:

    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.

    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??