Michigan Climate – Sep 2026September 2026 Update

Novarupta (Katmai) eruption

The largest volcanic eruption anywhere in the world in the 20th century - 13 km3 of magma, about thirty times the 1980 Mount St. Helens eruption - at Novarupta in Alaska on 6-8 June 1912. Ash reached 100,000 ft and cooled the Northern Hemisphere by roughly 0.3°C over 1912-13. Unlike a tropical eruption such as Pinatubo, a high-latitude eruption's haze stays in its own hemisphere, so it did little to the Southern Hemisphere.

Smithsonian Global Volcanism Program, Alaska Volcano Observatory, National Park Service, Oman et al. 2005

Post-WWII industrial expansion begins

After the Second World War, coal and oil use grew rapidly across Europe, North America and the Soviet Union. Global sulphur dioxide emissions rose from about 30 to about 130 million tonnes a year by 1980, and the sulphate haze they formed masked part of the greenhouse warming underneath - the effect known as 'global dimming'.

Klimont et al. 2013

The summer of 1953

1953 gave Michigan 20.6 heatwave days, its 2nd-highest of the 1950-2025 record, though it ranks only 16th-warmest by annual mean - a summer event, not a warm year.

Northeast Regional Climate Center, LIFE

The 1962-66 Northeast drought

1963 was Michigan's driest year in this site's 1950-2025 record - 623 mm, 24% below its 1961-90 average. It was not one dry year but five: 1962-66 as a whole averaged 10% below that baseline. This is the western edge of a drought centred on New England and the Mid-Atlantic, and it peaked a couple of years earlier here than on the coast.

USGS, Seager et al. 2012, NYC Emergency Management

Agung eruption

Agung's eruption in Bali put a veil of sulphate haze into the stratosphere that cooled global temperature by about 0.3°C over 1963-66.

Smithsonian Global Volcanism Program, NOAA Global Monitoring Laboratory

US Clean Air Act

The 1970 Clean Air Act set strict national standards for sulphur dioxide and particulates, and American skies got measurably cleaner over the decades that followed. There is a climate sting in that success: sulphate aerosols reflect sunlight, so removing them removed a cooling effect that had been partly masking greenhouse warming. Measured here, Michigan averaged +1.18°C warmer across 2006-2025 than across the two decades before the Act, 1951-1970, the 18th-largest rise of the 49 states measured and above their median of +1.09°C. Cleaning the air was right for human health. It also uncovered warming that was already there.

US EPA

The 1973-74 La Niña

The strongest La Niña of the 1950-present record, part of a multi-year cool phase that also included a second, separate La Niña in 1975-76.

ONI -2.0°C · RONI -1.9°C

NOAA CPCENSO Tracker

The 1976-77 drought

1976 was Michigan's 5th-driest year on record here - 709 mm, 13% below its 1961-90 average.

USGS, US GAO, USGS Water Data Labs

The cold winters of 1976-79

1979 is Michigan's 5th-coldest year in this site's 1950-2025 record. Its first months were the end of the winter of 1978-79, the coldest on record for the contiguous United States and the third brutal winter in a row across the Midwest.

Illinois State Water Survey, Missouri Climate Center, Monthly Weather Review (1978), Wikipedia

Pacific Decadal Oscillation flips to a warm phase

The Pacific Decadal Oscillation is a North Pacific pattern, and its influence on this side of the country is weak and indirect - mostly through how it nudges the winter jet stream downstream. Its 1976-77 flip marks a genuine shift in Pacific-basin climate, but for eastern states the Atlantic Multidecadal Oscillation is the ocean cycle that matters more.

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Global SO2 emissions peak

Global sulphur dioxide emissions peak at about 130 million tonnes a year, then begin a long decline as Europe, North America and Japan clean up their air. As the aerosol mask thins, the rate of global warming picks up through the 1980s.

Klimont et al. 2013

El Chichón eruption

A sulphur-rich eruption in Mexico whose aerosol cloud stayed in the stratosphere for more than two years, cooling the Northern Hemisphere by about 0.2°C.

Smithsonian Global Volcanism Program

1982-83 El Niño

El Niño has only a weak pull on Michigan's winter rainfall - it is not one of the seven states where ENSO reliably moves it. In 1982-83 Michigan's winter rainfall was close to its 1961-90 average (+7%), with temperatures +3.8°C. On NOAA's RONI index, which strips out background ocean warming, this is the strongest El Niño since 1950.

ONI +2.1°C · RONI +2.4°C

NOAA CPC, NOAA CPC (2)ENSO Tracker

1988 Midwest drought / Yellowstone fires

1988 was a dry, hot summer across the Midwest, but Michigan's own year was milder than its neighbours' - 34th-driest of 76 years and 15th-highest for heatwave days. The worst of it sat over the Corn Belt and northern Plains.

NOAA

Daytime warming catches up with the night-led pattern

Across 1961-90, 81% of the world's land saw nights warming faster than days. Across 1991-2020 the pattern reversed: 70% saw days warming faster, as the industrial haze that had been dimming daytime sunshine was cleaned up. The study compares two fixed thirty-year windows; measured as a turning point, this site's own global series turns around 1982.

Zhong et al. 2023

Mount Pinatubo erupts

Pinatubo's cooling is only faintly visible in Michigan's own record. 1993, two years after the June 1991 eruption, ranks 17th-coldest of the 76 years there, though 1996 and 2014 have since been colder. A single large eruption can hold temperatures down for two or three years; it cannot reverse the trend.

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Atlantic Multidecadal Oscillation flips to a warm phase

The Atlantic Multidecadal Oscillation flipped to a warm phase in 1995. It is an Atlantic cycle, but its reach is not confined to the coast: a warm AMO alongside a cool Pacific has been tied to more frequent drought across the western and central United States, including the widespread droughts of 1996 and 1999-2002. It is a natural cycle of roughly 60-70 years, so it shifts the baseline rather than driving the long-term trend.

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February 1996 Arctic outbreak, state record colds

Michigan sat on the eastern edge of the February 1996 outbreak. 1996 was its 6th-coldest year in this site's 1950-2025 record with its 5th-highest air-frost count - a hard winter, but the -60°F and -55°F state records belong to Minnesota and Wisconsin.

NWS La Crosse

1997-98 El Niño

In 1997-98 Michigan's winter rainfall was close to its 1961-90 average (-3%), with temperatures +4.8°C - though ENSO's pull on rainfall here is weak. It is often treated as the textbook strong El Niño.

ONI +2.4°C · RONI +2.3°C

NOAA CPC, NOAA NCEIENSO Tracker

Pacific Decadal Oscillation flips back to a cool phase

The Pacific Decadal Oscillation returned to a cool phase around 1998-99. Its direct effects are western - drier conditions across the south-west, changes in North Pacific fisheries - and its influence on this side of the country is weak and indirect. The Atlantic Multidecadal Oscillation, which flipped warm in 1995, is the ocean cycle with more bearing on eastern weather.

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Start of the sustained rise in US heatwave frequency

Michigan's own Heatwave Days (WSDI) count rose from a 1961-90 average of 3.6 days a year to 8.7 in 2016-25 - more than doubling, close to the 2.4x averaged across the 50 states.

World Bank CCKP (CCKP), NOAA Climate at a Glance

The 2012 drought and heat

Michigan recorded 30.4 heatwave days in 2012, more than in any other year of this site's 1950-2025 record, alongside its 2nd-warmest year - but rainfall finished only 22nd-driest of 76 years. In Michigan 2012 is remembered as the heat; the drought's worst conditions sat over the Plains and Corn Belt.

NOAA NCEI, Summer 2012 Drought Update, NOAA NCEI, Drought

Post-2013 acceleration in US temperatures

4 of Michigan's ten warmest years on record have occurred since 2013 - fewer than in most states - but 8 of the ten have come since 2000, with 2024 the warmest of all. The acceleration is clear in Michigan's data; its year-to-year swings are simply wide enough to spread the warmest years further apart than the national mean does.

NOAA Climate at a Glance

Great Lakes water-level swing, 2013 record low to 2020 record high

Jan 2013 record low (lowest since 1918 records began), followed by 2020 record highs after the region's wettest 60-month period in 120 years - a real, dramatic hydrologic swing documented by NOAA GLERL long-term data.

NOAA GLERL

The polar-vortex winter of 2013-14

2014 is Michigan's 2nd-coldest year in this site's 1950-2025 record - its coldest since 1972. In early January 2014 the polar vortex slipped south and Arctic air spread across most of the country, and the cold returned in waves into March.

Wikipedia, CBS NewsPolar Vortex Tracker

2015-16 El Niño

In 2015-16 Michigan's winter rainfall ran +35% against the 1961-90 average, with temperatures +4.3°C - though ENSO's pull on rainfall here is weak. By the raw ONI index it was the strongest El Niño ever measured - a reminder that a strong index does not guarantee a strong local outcome.

ONI +2.6°C · RONI +2.3°C

NOAA CPCENSO Tracker

2015-2025: the eleven warmest years on record

Globally, the eleven warmest years on record have all happened since 2015. In Michigan the pattern is weaker: only five of its eleven warmest fall in that span, with 2012, 2010, 2006, 2001, 1998 and 1987 outside it. Its warmest year is 2024. The warming is in Michigan's record; it simply arrives in a different order.

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2019: the wettest year across the Upper Midwest

2019 was Michigan's wettest year in this site's 1950-2025 record - 1,063 mm, 30% above its 1961-90 average. It came in the middle of the run that drove the Great Lakes to record high levels in 2020.

Wisconsin State Climatology Office / WPR, Midwestern Regional Climate Center, NWS Green Bay

Low-sulphur shipping fuel rule (IMO 2020)

New international shipping rules cut the sulphur allowed in ship fuel from 3.5% to 0.5% almost overnight, removing about 8 million tonnes of sulphur dioxide a year. With less sulphate haze over the oceans, it may have added around 0.1°C of warming by 2023-24.

Gettelman et al. 2024

2023-24 El Niño

A strong El Niño arriving on top of long-term greenhouse warming, with the cut in shipping sulphur from the 2020 fuel rule adding a little more. Together they produced the record global temperatures of 2023 and 2024.

ONI +2.0°C · RONI +1.4°C

NOAA CPCENSO Tracker