US South Climate – September 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

The Great Mississippi Flood of 1927

A levee break near Greenville flooded a million acres in 10 days; the Yazoo Delta was hardest-hit (~1,000 estimated deaths, 41,673 homes flooded statewide) of the era's greatest US flood disaster.

Mississippi Encyclopedia

The Dust Bowl

The defining environmental disaster of 1930s America. In the South it reached Kansas, Oklahoma and Texas.

Schubert et al. 2004, NCAR/UCAR

Louisiana's coastal wetland loss

USGS: Louisiana has lost ~1,900 sq mi of coastal wetlands since 1932, peak loss >100km²/yr in 1956-1978.

USGS

Black Sunday, the worst Dust Bowl storm

The worst single dust storm of the Dust Bowl years, and the day the phrase was coined. In the South it swept across Kansas, Oklahoma and Texas.

NWS Norman

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

Among the most widespread and sustained droughts ever recorded in the US - worse than the Dust Bowl in several states. It reached every state in the South, and the southern Plains were its centre.

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

How much ENSO really controls the South's winter rain

Of the fifty states, only seven have a December-February rainfall link to El Niño and La Niña strong enough to be worth reporting. In the South that is Texas, where ENSO explains 29% of the year-to-year swing in winter rainfall, and Louisiana, at 15%. Arkansas, Kansas, Mississippi and Oklahoma fall below that line, so weaker ENSO events are left off their pages.

NOAA CPC Oceanic Nino IndexENSO Tracker

1951: a cold, wet year and the Great Flood

1951 is Kansas's wettest year in this site's 1950-2025 record - 47% above its 1961-90 average - and its 2nd-coldest. That rain produced the Great Flood of 1951: in July the Kansas River overwhelmed Topeka and Kansas City, killing 17 people and displacing 518,000.

NWS Missouri Basin River Forecast Center, USGS

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

Hurricane Camille

One of only four Category 5 hurricanes ever to strike the continental US. It came ashore on the Mississippi coast and also hit Louisiana.

NWS Mobile, Mississippi Encyclopedia, Encyclopedia Virginia

US Clean Air Act

The 1970 Clean Air Act cut sulphur dioxide and particulate pollution across the country, and removing those sunlight-reflecting aerosols also removed a cooling effect that had been partly masking greenhouse warming. Across the South, 2006-2025 averaged +0.89°C warmer than the two decades before the Act, 1951-1970.

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

A flood of duration rather than height: 88 consecutive days of flood flow at Vicksburg. In the South it reached Arkansas, Kansas, Louisiana, Mississippi and Oklahoma.

USGS Professional Paper 937, NWS St. Louis

The 1975-76 La Niña

A strong, distinct La Niña following closely on the 1973-74 event, together forming one of the most sustained cool-phase periods in the ENSO record.

ONI -1.6°C · RONI -1.1°C

NOAA CPCENSO Tracker

The cold winters of 1976-79

Three severe winters in a row. January 1977 was probably the coldest month the eastern United States had seen in two centuries - Atlanta's coldest month ever measured - and the winter of 1978-79 was the coldest on record for the contiguous United States. Missouri had its coldest winter on record; Illinois had its coldest January-February, 14°F below normal, with seventeen major winter storms.

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

A three-month heat wave that killed at least 1,700 people across the country. In the South it hit Arkansas, Kansas, Mississippi, Oklahoma and Texas.

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 usually brings the South a wet winter. In 1982-83 it was: winter rainfall ran +56% against the 1961-90 average, with temperatures +1.0°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

Mild winters made 1990 the 7th-warmest year then recorded in the contiguous United States, and the 4th-warmest in the Northeast. January-February 1990 set the national record for those months, which stood until 1998, and 1991 was nearly as warm across much of the East.

News & Record / AP (1991), NOAA NCEI

Mount Pinatubo erupts

Pinatubo's aerosol veil left a clear mark on the South. 1993, two years after the June 1991 eruption, is the region's 10th-coldest year of the 76 on record and no year since has been colder there. A single large eruption can hold temperatures down for two or three years; it cannot reverse the trend.

Learn more →

Hurricane Andrew

A Category 5 landfall on south Florida, and the most expensive US natural disaster until Katrina. In the South, its second landfall was in Louisiana.

NOAA NESDIS, National Park Service

The Great Flood of 1993 (Mississippi River)

The greatest flood on record on the Upper Mississippi, with $36.3bn in losses. In the South it reached Kansas.

NASA Earth Observatory / NWS

Atlantic Multidecadal Oscillation flips to a warm phase

The Atlantic Multidecadal Oscillation flipped to a warm phase in 1995, and for the Gulf coast that has meant a more active hurricane season: the warm phase since includes Katrina and Rita in 2005, Harvey in 2017 and Ida in 2021. It is a natural cycle of roughly 60-70 years, so it shifts the baseline rather than driving the long-term trend.

Learn more →

1997-98 El Niño

El Niño usually brings the South a wet winter. In 1997-98 it was: winter rainfall ran +54% against the 1961-90 average, with temperatures +1.7°C. It is often treated as the textbook strong El Niño.

ONI +2.4°C · RONI +2.3°C

NOAA CPC, NOAA NCEIENSO Tracker

The 1999-2001 La Niña

A strong La Niña that ran for three winters after the record 1997-98 El Niño, peaking at an ONI of -1.53. La Niña usually leaves the South dry in winter, and that first winter split the region along the textbook line: Louisiana ran 52% below its 1961-90 average, Mississippi 46% and Texas 30%, while Kansas and Oklahoma, further from the Gulf, came in wetter than normal.

ONI -1.5°C · RONI -1.6°C

NOAA CPC ONI

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.

Learn more →

1999 Bridge Creek-Moore tornado

Recorded the highest tornado wind speed ever measured (321mph via Doppler radar), the first billion-dollar tornado in US history, 36 deaths.

Wikipedia (NWS-sourced)

Hurricane Katrina

The costliest US hurricane of its time, with 520 direct deaths. It hit Louisiana and Mississippi.

NOAA NHC, NWS Mobile, Climate Signals

2006: a national heat record that lasted six years

The warmest year ever recorded for the contiguous United States at the time - since pushed down to 10th. In the South it is still a top-five warm year in Kansas and Oklahoma.

NOAA NCEI, Science

The 2006-08 Southeast drought

The driest year on record in North Carolina and Tennessee, and the drought that took Atlanta's Lake Lanier to record lows. In the South it reached Mississippi.

NWS, NWS Key West, Florida BRACE, Florida Climate Center

The 2007-08 La Niña

A strong La Niña linked to reduced Atlantic hurricane wind shear and drought conditions across the southern US and East Africa.

ONI -1.8°C · RONI -1.7°C

NOAA CPCENSO Tracker

The Greensburg tornado

On the night of 4 May 2007 a tornado 1.7 miles wide destroyed about 90% of Greensburg, Kansas. It was the first tornado rated EF5 on the new Enhanced Fujita scale, with winds of about 205 mph, and the strongest since the 1999 Bridge Creek-Moore tornado. It killed 11 people in the town of about 1,500, and 13 across the outbreak.

NWS Dodge City, NOAA NCEI Storm Events

2009-10 El Niño

A moderate-to-strong El Niño that peaked around the turn of 2009-10. It helped make 2010 one of the warmest years on record at the time, and was followed straight away by the strong La Niña of 2010-12.

ONI +1.5°C · RONI +1.5°C

NOAA/IRI ENSO archiveENSO Tracker

The 2010-2012 La Niña

A strong double-winter La Niña peaking at an ONI of -1.57, and the direct driver of the worst single-year drought in Texas's history. Every state in the South was dry that first winter, between 26% and 46% below its 1961-90 average. Texas's driest 12 months on record, October 2010 to September 2011, sits inside this event.

ONI -1.6°C · RONI -1.6°C

NOAA CPC ONI

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

Across the six states of the South, Heatwave Days (WSDI) rose from a 1961-90 average of 4.1 days a year to 12.7 in 2016-25 - more than a threefold increase, with every one of them recording more heatwave days than in 1961-90. The spread inside the region is very wide: Texas 6.4x against Arkansas 1.9x.

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

Texas's driest 12 months on record, 2011

State climatologist confirmed Oct 2010-Sep 2011 was Texas's driest 12-month period since 1895; summer 2011 temperatures ~2°F above the prior state record; $7bn+ agricultural losses. A 2021 UT Austin study found it was even more severe than initially assessed.

UT Austin / Texas Tribune

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

A drought that covered about 70% of the country at its July peak. It reached every state in the South.

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

Post-2013 acceleration in US temperatures

Across the six states of the South, an average of 5.8 of each state's ten warmest years have come since 2013, ranging from 4 in Oklahoma to 8 in Mississippi. Every state in the region has at least 7 of its ten warmest since 2000.

NOAA Climate at a Glance

The polar-vortex winter of 2013-14

In early January 2014 the polar vortex slipped south and Arctic air spread from the Rockies to the Atlantic, affecting more than 200 million people. Chicago fell to -16°F on 6 January, and the cold returned in waves into March. It made 2014 one of the coldest years of recent decades across the Midwest and the South.

Wikipedia, CBS NewsPolar Vortex Tracker

2015-16 El Niño

El Niño usually brings the South a wet winter. In 2015-16 it was: winter rainfall ran +15% against the 1961-90 average, with temperatures +2.9°C. 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. The South follows it only partly: five of its own eleven warmest fall in that span, with 2012, 2011, 2006, 1999, 1998 and 1954 outside it. Its warmest year is 2024.

Learn more →

Nights warm faster than days in the South-East US

The clearest regional signal in US data of nights warming faster than days. It extends into the South through Arkansas, Louisiana and Mississippi, and Louisiana has one of the three largest narrowings of any US state.

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

Hurricane Harvey

The highest rainfall total from any tropical cyclone in US history, 60.58 inches, and the most thoroughly attributed extreme-rainfall event in the country. It hit Texas and Louisiana.

World Weather Attribution, van Oldenborgh et al. 2017, Risser & Wehner 2017, NOAA Climate.gov

The 2019 Arkansas River flood

A basin flood that broke Fort Smith's 74-year-old record crest twice in a week. It hit Arkansas, Kansas and Oklahoma.

NWS Little Rock, Encyclopedia of Arkansas

The 2019 flash drought

A flash drought that took the share of the Southeast in drought from 25% to 80% in a single month. In the South it reached Mississippi.

NOAA Climate.gov, NOAA NCEI, Wang et al. 2021

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

Winter Storm Uri (Texas freeze), February 2021

Texas's coldest winter storm since December 1989 - 6-9 consecutive days below freezing in central Texas (longest freezing streak on record there), parts of East Texas the coldest since ~1890. 210+ deaths in Texas, the first billion-dollar US weather disaster of 2021, massive power-grid failure. It followed a sudden stratospheric warming in early January 2021 that disrupted the polar vortex and let Arctic air plunge south across the Plains.

NOAA NCEIPolar Vortex Tracker

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

The Texas Hill Country floods, July 2025

Overnight into 4 July 2025, storms fed by moisture from the remnants of Tropical Storm Barry stalled over the Texas Hill Country and dropped 2-3 inches of rain an hour onto the headwaters of the Guadalupe River. The river rose more than 20 feet in a few hours through Kerr County, sweeping through riverside homes and summer camps. More than 130 people died across central Texas, over 100 of them in Kerr County, among them children at Camp Mystic.

NOAA NESDIS, Texas Public Radio