Missouri 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 1950s drought

Missouri's worst year of the 1950s drought was 1953 for rainfall, its driest in this site's 1950-2025 record (638 mm, 39% below its 1961-90 average) - and 1952 for heat, with 35.1 heatwave days, its 2nd-highest.

NOAA Drought.gov, NOAA Climate Program Office, Texas Water Development Board

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, Missouri averaged +0.79°C warmer across 2006-2025 than across the two decades before the Act, 1951-1970, the 4th-smallest rise of the 49 states measured. That is not an absence of warming - every one of them is warmer than it was - but the southern Plains and mid-South warmed least of anywhere in the country over this period, a regional quirk researchers call the 'warming hole'. Missouri sits inside it.

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 Mississippi flood of 1973

1973 is Missouri's wettest year in this site's 1950-2025 record - 1451 mm, +39% against its 1961-90 average. The Mississippi crested at St. Louis on 28 April 1973, 12.2 ft over flood stage - its highest level in more than 150 years, and the record until 1993 broke it.

USGS Professional Paper 937, NWS St. Louis

The 1976-77 drought

1976 was Missouri's 2nd-driest year on record here - 725 mm, 30% below its 1961-90 average.

USGS, US GAO, USGS Water Data Labs

The cold winters of 1976-79

1979 is Missouri's 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. It was Missouri's coldest winter on record.

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.

Learn more →

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

The 1980 heat wave and drought

1980 gave Missouri 19.6 heatwave days, its 7th-highest of the 1950-2025 record, alongside its 3rd-driest year. Nearly 400 Missourians died, 339 of them in the fortnight of 8-21 July alone, and Kansas City recorded 176 deaths. The city's high passed 100°F for 17 consecutive days and dropped below 90°F only twice all summer. By annual mean temperature, though, 1980 ranks only 33rd-warmest here - a summer event, not a warm year.

NOAA NCEI Billion-Dollar Disasters, Linda Hall Library, Karl & Quayle 1981

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 Missouri's winter rainfall - it is not one of the seven states where ENSO reliably moves it. In 1982-83 Missouri's winter rainfall ran +49% against the 1961-90 average, with temperatures +2.7°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 Missouri's 11th-driest year - 869 mm, 17% below its 1961-90 average. The heat was less extreme (9.9 heatwave days, 18th-highest); in Missouri 1988 is the drought rather than the heatwave.

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

1990-91: mild winters and warm years

1990 is Missouri's 15th-warmest year in this site's 1950-2025 record. Mild winters did most of it: January-February 1990 was the warmest start to a year the contiguous US had recorded, a record that stood until 1998.

News & Record / AP (1991), NOAA NCEI

Mount Pinatubo erupts

Pinatubo's aerosol veil left a clear mark on Missouri. 1993, two years after the June 1991 eruption, is Missouri's 7th-coldest year of the 76 on record, 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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The Great Flood of 1993 (Mississippi River)

1993 was Missouri's 2nd-wettest year in this site's 1950-2025 record - 1438 mm, 38% above its 1961-90 average.

NASA Earth Observatory / NWS

Atlantic Multidecadal Oscillation flips to a warm phase

The Atlantic Multidecadal Oscillation flipped to a warm phase in 1995. Atlantic hurricanes reach this far inland mostly as remnants - Helene's floods in east Tennessee in 2024 among them - and warm AMO phases have also been linked to more frequent drought across the central United States. 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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1997-98 El Niño

In 1997-98 Missouri's winter rainfall ran +25% against the 1961-90 average, with temperatures +3.2°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

Missouri's own Heatwave Days (WSDI) count rose from a 1961-90 average of 5.7 days a year to 12.0 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 Joplin tornado

An EF5 tornado about a mile wide tracked 22 miles through Joplin on the evening of 22 May 2011, killing 161 people and injuring more than a thousand. It is the deadliest single tornado in the United States since official records began in 1950.

NIST, NWS

The 2012 drought and heat

Missouri recorded 42.3 heatwave days in 2012, more than in any other year of this site's 1950-2025 record, alongside its warmest annual mean and its 5th-driest year. The Missouri Climate Center measured just 5.8 inches of May-July rainfall - the 3rd-driest such period in 126 years, the worst state drought in 30 years, and the first 100°F+ June heat since 1988.

NOAA NCEI, Summer 2012 Drought Update, NOAA NCEI, Drought, Missouri Climate Center

Post-2013 acceleration in US temperatures

5 of Missouri's ten warmest years on record have occurred since 2013 - fewer than in most states - but 7 of the ten have come since 2000, with 2012 the warmest of all. The acceleration is clear in Missouri'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

The polar-vortex winter of 2013-14

2014 is Missouri's 5th-coldest year in this site's 1950-2025 record - its coldest since 1979. 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 Missouri's winter rainfall ran +52% against the 1961-90 average, with temperatures +3.5°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. Missouri does not follow it: its hottest year is still 2012, the drought year. Five of its own eleven warmest fall in the 2015-2025 span, with 2012, 2006, 1999, 1998, 1954 and 1953 outside it. Missouri is one of 15 states where 2012 still tops the list.

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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