Arkansas 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

Arkansas's worst year of the 1950s drought was 1954 for rainfall - 3rd-driest year (960 mm, 25% below its 1961-90 average) - and 1953 for heat, with 38.3 heatwave days, more than any year on record here.

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, Arkansas averaged +0.71°C warmer across 2006-2025 than across the two decades before the Act, 1951-1970, the 2nd-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'. Arkansas 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 was Arkansas's 3rd-wettest year on record here - 1778 mm, +40% against its 1961-90 average.

USGS Professional Paper 937, NWS St. Louis

The cold winters of 1976-79

1979 is Arkansas'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.

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

The 1980 heat wave and drought

1980 gave Arkansas 23.5 heatwave days, its 8th-highest of the 1950-2025 record, alongside its 6th-driest year. Arkansas was among the worst-affected states for heat deaths. Little Rock recorded 47 days at or above 100°F that summer. By annual mean temperature, though, 1980 ranks only 38th-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 Arkansas's winter rainfall - it is not one of the seven states where ENSO reliably moves it. In 1982-83 Arkansas's winter rainfall ran +47% against the 1961-90 average, with temperatures +1.5°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

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 Arkansas's 12th-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 Arkansas. 1993, two years after the June 1991 eruption, is Arkansas's 12th-coldest year of the 76 on record, though 2014 has 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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1997-98 El Niño

In 1997-98 Arkansas's winter rainfall ran +32% against the 1961-90 average, with temperatures +2.0°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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Arkansas's 2010-2012 drought

Arkansas's longest drought since monitoring began ran from April 2010 to March 2012, and 2010 and 2012 are the 4th and 5th driest years in this site's 1950-2025 record. The year between them broke the pattern. 2011 finished 11% WETTER than average, yet still delivered the 5th-highest heatwave-day count on record. A wet spring followed by a fierce, dry summer leaves an annual rainfall total looking unremarkable while the drought carries straight on underneath it.

NOAA State Climate Summaries, Arkansas, Encyclopedia of Arkansas

Start of the sustained rise in US heatwave frequency

Arkansas's own Heatwave Days (WSDI) count rose from a 1961-90 average of 5.4 days a year to 10.3 in 2016-25 - a clear rise, though more moderate than the 2.4x averaged across the 50 states.

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

The Albert Pike flood

Before dawn on 11 June 2010, 6-8 inches of rain sent the Little Missouri River up about 20 feet in a few hours through the Albert Pike Recreation Area in the Ouachita Mountains. Twenty campers died - the deadliest single flood in Arkansas's recorded history.

USGS, NOAA NCEI Storm Events

The 2012 drought and heat

Arkansas recorded 30.1 heatwave days in 2012, its 4th-highest on record here, alongside its warmest year on record and its 5th-driest year (1011 mm).

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

Post-2013 acceleration in US temperatures

5 of Arkansas'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 Arkansas'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 Arkansas's 3rd-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 Arkansas's winter rainfall ran +12% against the 1961-90 average, with temperatures +3.0°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. Arkansas 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, 2005, 1999, 1998 and 1954 outside it. Arkansas is one of 15 states where 2012 still tops the list.

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Nights warm faster than days in the South-East US

Arkansas's nights have warmed far faster than its days. Against the 1950-2014 average, the 2015-2025 period runs +1.15°C on overnight minimum temperature but only +0.61°C on daytime maximum - nights warming roughly 1.9 times as fast. The gap between day and night has closed by 0.53°C, the 7th-largest narrowing of any US state.

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

The 2019 Arkansas River flood

Arkansas took the flood the other two states caused. Fort Smith broke its 1945 record crest of 38.1 ft twice inside a week, reaching 40.79 ft on 1 June 2019, and a levee near Dardanelle lost a 40-foot section to the current with 300-400 homes behind it. 2019 was Arkansas's 6th-wettest year in this site's 1950-2025 record. In July the remnants of Hurricane Barry then dropped 16.17 inches on Dierks - the most rain ever measured in 24 hours anywhere in the state.

NWS Little Rock, Encyclopedia of Arkansas

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