Georgia 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

1954 was Georgia's driest year in this site's 1950-2025 record - 789 mm, 39% below its 1961-90 average.

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

How much ENSO really controls Georgia's winter rain

Across the fourteen ENSO events in this site's record, Georgia's winter rainfall followed the index in six of six El Niños and six of eight La Niñas. The index explains about 19% of the year-to-year variation in Georgia's December-February rainfall. The extremes: 1997-98 came in +47% against the 1961-90 average, 1988-89 -49%.

NOAA CPC Oceanic Nino IndexENSO Tracker

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, Georgia averaged +1.04°C warmer across 2006-2025 than across the two decades before the Act, 1951-1970, against a median of +1.09°C across the 49 states whose records reach back that far. Every one of them warmed. The range runs from +0.66°C in Oklahoma to +1.67°C in Alaska, so the question a state's own chart answers is not whether it warmed, but by how much.

US EPA

The 1973-74 La Niña

Globally this was a strong La Niña in the middle of a sustained multi-year cool phase. In Georgia it showed up as winter rainfall 19% above the 1961-90 average - its 11th-largest ENSO rainfall swing on record.

ONI -2.0°C · RONI -1.9°C

NOAA CPCENSO Tracker

The cold winters of 1976-79

1976 is Georgia's coldest year in this site's 1950-2025 record. It closed with the onset of the winter of 1976-77, one of the most severe on record in the East: January 1977 was probably the coldest month the eastern United States had seen in two centuries, and Atlanta's coldest month ever measured.

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

Globally this was the strongest El Niño since 1950 on NOAA's RONI index, which strips out background ocean warming. In Georgia it showed up as winter rainfall 21% above the 1961-90 average - its 10th-largest ENSO rainfall swing on record.

ONI +2.1°C · RONI +2.4°C

NOAA CPC, NOAA CPC (2)ENSO Tracker

The 1988-89 La Niña

Georgia's winter rainfall ran 49% below its 1961-90 average in the 1988-89 La Niña - its largest ENSO rainfall swing on record.

ONI -1.9°C · RONI -1.9°C

NOAA CPCENSO 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 Georgia's 6th-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 cooling is only faintly visible in Georgia's own record. 1993, two years after the June 1991 eruption, ranks 26th-coldest of the 76 years there, though 1996, 1997, 2010 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, and for the Southeast that has meant a more active hurricane season: the warm phase since includes Florence and Michael in 2018 and Helene in 2024. 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

Globally this was the strongest El Niño ever measured by the raw ONI index. In Georgia it showed up as winter rainfall 47% above the 1961-90 average - its 2nd-largest ENSO rainfall swing on record.

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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The south Georgia tornadoes of February 2000 (Camilla)

Late on 13 February 2000 and into Valentine's Day, three strong night-time tornadoes crossed south-west Georgia, killing 19 people - 11 in and around Camilla, where an F3 tore through two subdivisions and four mobile home parks. Around 200 homes were destroyed. It was south Georgia's deadliest tornado event in nearly 50 years.

NWS Tallahassee, NOAA NCEI Storm Events

The 2006-08 Southeast drought

2007 was Georgia's 2nd-driest year on record here - 25% below its 1961-90 average - and the same year its lowest relative humidity of any year in that record. The two go together: parched ground and dried-out vegetation stop returning moisture to the air, so the humidity that normally hangs over the south-east simply was not there. Lake Lanier, Atlanta's water supply for more than three million people, reached record lows by December 2007, prompting a state of emergency and outdoor watering bans.

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

The September 2009 Atlanta floods

Days of continuous rain in September 2009 produced what USGS classified as 500-year floods across metro Atlanta and northern Georgia. Eighteen streamgages exceeded the 0.2% annual-exceedance level, some breaking records more than a century old, and one location in Douglas County took over 21 inches in 24 hours. Ten people died, 20,000 buildings were badly damaged and 23 counties received federal disaster declarations.

USGS, NWS Peachtree City

Start of the sustained rise in US heatwave frequency

Georgia's own Heatwave Days (WSDI) count rose from a 1961-90 average of 7.3 days a year to 16.2 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

Post-2013 acceleration in US temperatures

7 of Georgia's ten warmest years on record have occurred since 2013, and 8 of the ten since 2000, with 2019 the warmest of all.

NOAA Climate at a Glance

2015-16 El Niño

Globally this was tied with 1997-98 as the strongest on the raw ONI index. In Georgia it showed up as winter rainfall 26% above the 1961-90 average - its 9th-largest ENSO rainfall swing on record.

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. Georgia follows closely: eight of its own eleven warmest fall in that span, with 2012, 1998 and 1990 outside. Georgia's warmest year is 2019.

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Nights warm faster than days in the South-East US

Georgia's nights have warmed far faster than its days. Against the 1950-2014 average, the 2015-2025 period runs +1.35°C on overnight minimum temperature but only +0.94°C on daytime maximum - nights warming roughly 1.4 times as fast. The gap between day and night has closed by 0.41°C, the 13th-largest narrowing of any US state.

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

The 2019 Southeast flash drought

2019 gave Georgia more heatwave days than any year in this site's 1950-2025 record (36.5), and its warmest year overall. September 2019 was Georgia's driest September in records back to 1895, and Atlanta had its hottest September ever measured. The year's rainfall still finished mid-table, 31st-driest of 76 - a drought this sharp can come and go without moving the annual figure.

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

2023-24 El Niño

Globally this was a strong El Niño, the first since 2015-16. In Georgia it showed up as winter rainfall 6% above the 1961-90 average - its 13th-largest ENSO rainfall swing on record.

ONI +2.0°C · RONI +1.4°C

NOAA CPCENSO Tracker

Hurricane Helene

Helene crossed Georgia as a strong tropical storm on 27 September 2024, still carrying damaging winds well inland - Augusta and much of eastern Georgia lost power for days, and agricultural losses were severe. The catastrophic flooding lay further north, in the mountains.

NOAA Climate.gov, World Weather Attribution