South America Climate – Sep 2026September 2026 Update
South America recorded marked warmth across its equatorial northern regions this month, driven by an intensifying ocean pattern in the tropical Pacific that is tightening its grip on the continent…
Top 5 Countries: Brazil, Argentina, Colombia, Peru, and Chile
Data for Continents is averaged from country snapshots. See Methodology.
Summary
South America recorded marked warmth across its equatorial northern regions this month, driven by an intensifying ocean pattern in the tropical Pacific that is tightening its grip on the continent. Equatorial northern nations bore the brunt of elevated temperatures, which triggered heightened drought pressure across the Amazon basin and helped fuel 24 wildfire clusters in Brazil. This broad regional warming reflects a strong El Niño forecast to peak at Very Strong in Sep-Nov. Looking ahead, persistent upper-level ridges and shifting rainfall patterns threaten to amplify dry conditions across northern South America over the coming months.
This month in numbers
South America registered a 1-month temperature anomaly of +1.41°C above the 1961-1990 baseline, matching its 3-month figure of +1.41°C and maintaining an elevated 12-month rolling anomaly of +0.96°C. While warmth dominated much of the landmass, southern temperate zones diverged dramatically from the equatorial north. Across global comparisons, the continent contained the single coldest territory tracked anywhere on Earth this month, creating a sharp regional thermal divide.
Hottest & coolest countries
The strongest thermal departures were concentrated near the equator, led by Guyana at +2.82°C above baseline, followed closely by Suriname at +2.70°C and Ecuador at +2.38°C. In contrast, southern South America experienced unseasonably cool air masses, where Uruguay recorded the strongest negative anomaly across the entire continent at -0.73°C, while neighbouring Argentina remained much milder at +0.21°C.
What's driving change?
The primary driver behind the continent's climate anomalies is the tropical Pacific, where an active phase of ENSO continues to alter atmospheric circulation. According to NOAA indices tracked at ENSO, a strong El Niño with a Relative Niño Index of +1.69°C is forecast to peak at Very Strong in Sep-Nov with a 100% probability. This ocean warming promotes and across northern South America, where reduced humidity and low rainfall exacerbate thermal stress and land drying. The resulting fire-weather conditions are already visible on the ground, with 24 active wildfire clusters across Brazil tracked on our live map at Extreme Weather tracker. Meanwhile, ongoing across the tropical rainforest biome further reduces natural evaporative cooling, leaving ecosystems increasingly vulnerable to scorching temperature spikes.
Looking ahead
Seasonal forecast models indicate that persistent warm and dry anomalies will continue across northern and central South America over the next 1-3 months as El Niño approaches its expected peak, maintaining elevated drought and wildfire risks across the Amazon basin.
Precipitation, Sunshine, Frost and Snow are converted to standard deviations from their own average so they can share an axis with Temperature anomalies.
Metric
Insight
Temperature
10-Yr AverageActual Year
Climate History
52 of 52 events
1912Volcanic
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.
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'.
One of the strongest La Niñas since instrument-based ENSO records begin in 1950, and part of a run of cool Pacific years through the mid-1950s. La Niña cools global temperatures slightly for a year or two while it lasts, and shifts rainfall patterns worldwide.
Charles David Keeling begins continuous measurements of atmospheric CO₂ at Mauna Loa Observatory in Hawaii, starting at about 315 ppm. The record has risen every year since and is now the longest unbroken direct measurement of CO₂ anywhere - the 'Keeling Curve'.
One of the strongest El Niños on record. It contributed to failed grain harvests in the Soviet Union and elsewhere in 1972, and to a sharp rise in world food prices - an early sign of how far ENSO's reach extends.
1975 is Brazil's 5th-coldest year in this site's 1950-2025 record. On 17-18 July 1975 a polar air mass brought the worst frost of the century to southern Brazil. It killed about 1.5 billion coffee trees, well over half of Brazil's total, devastated Paraná's coffee lands and sent world coffee prices up nearly fivefold by 1977.
The Pacific Decadal Oscillation - a slow natural cycle in North Pacific sea temperatures - switches from its cool to its warm phase in 1976-77. The change was abrupt enough to be called the 1976-77 Pacific Climate Shift: it warmed Alaska and the west coast of North America, and reorganised North Pacific fisheries.
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.
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.
The strongest El Niño since 1950 on NOAA's Relative Oceanic Niño Index, which strips out the background warming of the tropical oceans before ranking events. On the older index that leaves that warming in, 2015-16 comes out on top instead.
British Antarctic Survey scientists Joe Farman, Brian Gardiner and Jon Shanklin publish their Halley and Faraday measurements on 16 May 1985, showing October ozone over Antarctica had fallen to about two-thirds of earlier decades. The cause is traced to chlorofluorocarbons, and the finding triggers the fastest international environmental response on record.
Signed in 1987 to phase out ozone-depleting chlorofluorocarbons, the Montreal Protocol turned out to be one of the most consequential climate treaties ever agreed. CFCs are potent greenhouse gases in their own right, and NOAA estimates the Protocol prevented up to 2°C of warming by 2100 - around 1°C from the emissions avoided, and up to 1°C more by sparing forests and other carbon sinks from increased ultraviolet radiation.
Atmospheric CO₂ passes 350 ppm. In the same year James Hansen told a US Senate committee that global warming was already detectable, the moment it entered mainstream politics. Twenty years later, in 2008, Hansen proposed 350 ppm as the safe upper limit - a level the world had already left behind.
One of the strongest La Niñas on record, arriving straight after the 1986-87 El Niño - a swing from one extreme of the Pacific cycle to the other in barely a year.
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.
Mount Pinatubo in the Philippines erupts in June 1991, the largest eruption since 1912. Its sulphate haze cooled global surface temperature by about 0.5°C in 1992 and reduced rainfall over land for about two years, before the warming trend resumed.
Atlantic Multidecadal Oscillation flips to a warm phase
The Atlantic Multidecadal Oscillation - a slow natural cycle in North Atlantic sea temperatures, roughly 60-70 years long - flips to its warm phase in 1995. Warm phases are linked to more active Atlantic hurricane seasons, wetter summers in parts of north-west Europe and more frequent drought in the central and western United States.
One of the strongest El Niños on record, and the one the textbook El Niño pattern is usually drawn from. It pushed 1998 to what was then the warmest year ever measured, and set off the first global-scale coral bleaching event.
A strong La Niña that ran for three winters after the record 1997-98 El Niño, peaking at an ONI of -1.53. It pulled global temperatures back below 1998's record for several years, and brought the usual La Niña pattern of dry winters across the southern United States and wet years in Australia and Indonesia.
Pacific Decadal Oscillation flips back to a cool phase
The Pacific Decadal Oscillation - a slow natural cycle in North Pacific sea temperatures - flips back to its cool phase around 1998-99. The cool phase that followed is one reason global surface warming appeared to slow in the 2000s, as more heat went into the deep Pacific.
In December 1999 about 911 mm of rain fell in a few days on Venezuela's Vargas coast, north of Caracas, setting off flash floods and debris flows that buried whole towns. Estimates of the dead range from 10,000 to 30,000, the worst natural disaster in Venezuela's modern history.
By mid-January 2005 about 27 inches of rain had fallen on Guyana's coast, nearly four times the monthly norm, and high tides and an overtopped water conservancy flooded Georgetown and the coastland for weeks. About 290,000 people - 39% of the population - were affected, and losses equalled 59% of GDP.
Heavy rain in May 2006 brought the worst floods in memory to Suriname's interior. More than 150 Indigenous and Maroon villages along the rivers stood in up to two metres of water; over 25,000 people were affected and about two-thirds of their crops were lost.
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.
Drought during the 2009-10 El Niño cut the flow into the Guri dam, which supplied most of Venezuela's electricity. From early 2010 the government rationed power in Caracas and other cities for about five months to stop the reservoir falling to a level that would shut down the turbines.
Globally, heatwave days have roughly doubled each decade since 2010 - from an average of 5.3 a year in the 2000s to 11.5 in the 2010s and 18.9 so far in the 2020s, weighted by land area across 169 countries. El Niño has not become more extreme. The whole temperature distribution has shifted upwards, so the same natural El Niño and La Niña cycle now pushes far more days over fixed extreme-heat thresholds.
A strong double-winter La Niña peaking at an ONI of -1.57. It gave Australia its wettest two years on record and the Queensland floods of 2010-11 - so much rain fell on land that global sea level briefly dropped in 2011 - and it fed drought in the Horn of Africa and in Texas.
From 2010 central Chile had more than a decade of dry years in a row, with 20 to 40% less rain than normal. Tree-ring records back to the year 1000 show nothing comparable. Reservoirs ran low, and the parched land fed a run of megafires, including the worst wildfire season in Chile's modern history in 2017.
The strong 2010-11 La Niña brought Colombia its most damaging rainy season in over 40 years. By the end of 2010 rain and floods had affected more than 2.4 million people and killed over 300, with losses later put at more than US$7.8 billion.
On 12 January 2011 about a month's rain fell in under a day on the mountains north of Rio de Janeiro. Flash floods and mudslides tore through Nova Friburgo, Teresópolis and Petrópolis, killing more than 900 people - Brazil's deadliest natural disaster in recent history.
Atmospheric CO₂ passes 400 ppm at Mauna Loa on 9 May 2013 - a level the planet had not seen for 3-5 million years, since the Pliocene, when sea levels were many metres higher.
On the night of 2 April 2013 a storm dropped close to 400 mm of rain on La Plata, capital of Buenos Aires province, in a few hours. Water rose inside homes before people could escape; 89 people died, and Buenos Aires flooded the same night.
Two failed rainy seasons left south-east Brazil in its worst drought on record. The Cantareira reservoirs, which supplied about 9 million people in greater São Paulo, fell to about 5% of capacity by January 2015, and losses in 2014 alone reached about US$5 billion.
The strongest El Niño on record by raw ONI - though on NOAA's newer RONI index, which strips out background tropical-ocean warming, 1982-83 ranks slightly ahead instead. 2016 became the hottest year on record at that time (+1.0°C above pre-industrial).
The eleven warmest years ever measured are 2015 through 2025, an unbroken run - the longest sustained stretch of record warmth in the 176-year instrumental record. 2023 and 2024 each broke the previous record in turn.
In December 2015, during the strong El Niño, Lake Poopó - Bolivia's second-largest lake - was declared evaporated, leaving a salt flat on the Altiplano. Drought and years of water diverted for mining and farming finished it off; fish and birds died by the million and fishing families had to leave. In 2016 La Paz faced water rationing in Bolivia's worst drought in decades.
Heavy El Niño rains in December 2015 swelled the Paraguay, Paraná and Uruguay rivers beyond flood stage, in the region's worst floods in decades. Paraguay was hit hardest: more than 100,000 people were evacuated, most of them from riverside districts of Asunción.
In early 2017 the sea off Peru and Ecuador warmed sharply, a 'coastal El Niño' that the Pacific-wide ENSO index barely registered. Months of heavy rain and mudslides on Peru's normally dry coast affected 1.5 million people and killed 162.
Global fossil CO₂ emissions fell about 5.8% in 2020, from 37.0 to 34.8 billion tonnes, yet atmospheric CO₂ still rose 2.5 ppm - the dip barely registers in the atmospheric record. Emissions were back to pre-pandemic levels by 2022.
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.
Three consecutive La Niña winters - a 'triple dip', which has happened only a handful of times since 1950 - peaking at an ONI of -1.11. It held global temperatures slightly below where the warming trend would otherwise have put them, and coincided with five failed rainy seasons in a row in the Horn of Africa and severe flooding in eastern Australia in 2022.
Drought across the upper Paraná basin dropped the Paraguay River at Asunción to 56 cm below its reference mark in September 2021, the lowest since records began in 1904 and below the record set a year earlier. For a landlocked country that ships most of its exports by river barge, it threatened huge losses.
The 2020-23 'triple-dip' La Niña left Argentina in its worst drought in 60 years. The 2023 harvest came in at around half the previous year's, costing farmers about US$10 billion and knocking some two points off the country's GDP.
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.
In October 2023 the Rio Negro at Manaus fell to 12.70 m, its lowest since records began in 1902 - and a year later it went lower still, to 12.66 m, against a normal level of about 21 m. The drought stranded river communities and fed the worst fires in more than a decade in Brazil and Bolivia.
In the first days of February 2024, after days of extreme heat, fires swept into the hills around Viña del Mar and Valparaíso. 136 people died - Chile's deadliest wildfire on record and the country's worst disaster since the 2010 earthquake - in a region already dried out by more than a decade of megadrought.
In 2024 Ecuador, which gets about three-quarters of its electricity from hydropower, had its worst drought in 60 years. The Mazar reservoir stopped generating, and from September blackouts lasted up to 14 hours a day across the country, costing the economy about US$2 billion.
Floods in April and May 2024 reached 478 of Rio Grande do Sul's 497 municipalities, including much of Porto Alegre. At least 181 people died, more than 420,000 were displaced and damage passed US$15 billion. World Weather Attribution found climate change made the rainfall twice as likely.
Warm Spell Duration Index (WSDI) - days in a 6+ day run above the local 90th-percentile temperature for that time of year. Equal-weight mean across 8 countries.
Heatwave days per year2024 (Record)10-yr avg
Data: World Bank Climate Change Knowledge Portal (ERA5-derived), aggregated by 4BYO across member countries. Refreshed roughly 1-2x/year, ~7-8 months behind present.
Source: Copernicus ERA5 (countries) · NOAA Climate at a Glance (continents, US states & climate regions) · Met Office (UK) · GPCC (rainfall, snow) · World Bank CCKP (frost). Anomalies are vs the 1961–1990 baseline. See methodology.
4byo continent aggregate · equal-weight mean of 8 country monthly absolute temperatures (OWID/CRU TS); precipitation: GPCC (DWD). - Anomalies vs 1901-2000 mean
South America doesn't have a warm/cold cycle - its monthly temperature range is only 4.1°C across the year - but it does have a strong wet/dry cycle (the wettest month gets 3× as much rain as the driest). So we track how the wet season has shifted instead.
Shifting wet season
1 Day Shorter
Wet Season
1891–1920 Baseline: 29 Nov → 13 Apr · 135 days
2016–2025 Now: 1 Dec → 14 Apr · 134 days
+2d+1d
JanJFebFMarMAprAMayMJunJJulJAugASepSOctONovNDecD
Onset 2 Days LaterEnd 1 Day Later
-1.2% annual rain
baseline avgrecent avgClickTap for decades
Wet-season onset
29 Nov→1 Dec
2 Days Later
When 25% of annual rain has fallen
Wet-season end
13 Apr→14 Apr
1 Day Later
When 75% of annual rain has fallen
Peak-rain month
Mar→Mar
Unchanged
Wet months: 6 → 6
1891–19202016–2025Wet-month threshold (125 mm)
Monthly precipitation climatology. A “wet month” exceeds the baseline monthly mean (dashed gold line). Biggest month-to-month shift: Sep (-8 mm, -10%).
4byo continent aggregate · OWID/CRU TS country monthly temperatures & precipitation: GPCC (DWD). Baseline: first 30 yrs on record. Recent: last 10 yrs on record.
Live GDACS alerts in South America - Red (Major), Orange (Severe) or Green (Moderate) - and the long-term record of weather and climate disasters.
Live Alerts
Loading…
Alerts, Last 12 Months
Major
0
0.8 a year since 2021
Severe
3
2.8 a year since 2021
Moderate
619
Weather Disasters, 2025
Disasters
36
35 a year, 2016-2025
Deaths
599
434 a year, 2016-2025
Weather Disasters, 2016-2025
Most Frequent
Flood
231 of 351 disasters
Deadliest
Flood
2,842 of 4,341 deaths
Disasters: EM-DAT, CRED / UCLouvain, via Our World in Data - 10+ deaths, 100+ people affected, or a declared emergency or call for international help. Alerts: GDACS.
The natural climate patterns that measurably shape seasonal temperature or rainfall in South America, from this site’s own data since 1950 - long-term trends removed, and ENSO’s share taken out before scoring the others, so each is credited only for what it adds.
El Niño / La Niña (ENSO)moderate link
The tropical Pacific’s warm and cool swings - the biggest natural driver of year-to-year climate.
Now: El Niño (strong) · RONI +1.7°C(Jul-Sep 2026)
Forecast - 100% very strong at peak, Sep-Nov, then neutral by Apr-Jun 2027 (NOAA). La Niña from Sep 2027 in SNU’s AI model.
A moderate or strong link for 100% of the places in this group.
Every figure on this page is sourced from official, openly published climate datasets. Anomalies are calculated against the 1961–1990 baseline (temperature) and 1991–2020 (rainfall, sunshine, frost) - see the Methodology & Sources page for the complete dataset list and update calendar.
South America is warming in line with the rest of the world. The page above shows the latest monthly temperature anomaly versus the 1961-1990 baseline, the long-term annual trend, and the region's rank in the historical record. The headline panel also shows the long-term trend rate per decade and the warmest and coolest years on file.
Which climate drivers affect the weather in South America?
Measured from seasonal temperature and rainfall in South America since 1950, with the long-term warming trend removed (and ENSO's own share removed before scoring the other drivers), the climate drivers with a clear effect here are: El Niño / La Niña (ENSO) - a moderate or strong link for 100% of the places in this group. Their current state is shown in the Climate Drivers section of this page.
What extreme weather affects South America?
In 2025, the latest complete year, the international disaster database EM-DAT recorded 36 weather and climate disasters in South America, against an average of 35 a year in 2016-2025, with 599 deaths. Over those ten years the most frequent type was flood (231 of 351) and the deadliest flood. GDACS, the UN and European Commission's disaster alert system, issued 0 Major (Red) and 3 Severe (Orange) alerts for South America in the last 12 months. Live alerts are on this page and on the Extreme Weather tracker.
Where does the climate data for South America come from?
Climate data for South America comes from Our World in Data, sourcing Copernicus ERA5 and HadCRUT5 (national temperature anomaly) and the Global Carbon Project via Our World in Data (CO₂ emissions), refreshed every month, when the upstream temperature and rainfall data are refreshed.
What is the climate baseline used on this page?
Anomalies on this page are calculated against the 1961-1990 climatological baseline, which is the standard reference period used by the Met Office, NOAA, IPCC and most national climate services. Some panels also show the source-native 1901-2000 (NOAA) or 1991-2020 (WMO) baselines for verification. See Methodology & Sources for the full reference.
Which areas does the South America climate data cover?
The South America climate profile covers Brazil, Argentina, Colombia, Peru and surrounding areas. Aggregated from country snapshots - NOAA does not publish a SA continental series
How often is the South America climate update refreshed?
The South America climate update is refreshed monthly, typically a few days after the previous month closes and the upstream provider (Met Office HadUK-Grid, NOAA Climate at a Glance, Copernicus ERA5 or the Global Carbon Project) publishes its update. See the Climate Rankings for cross-region comparisons.
What counts as a Heatwave Day on the South America climate page?
Heatwave Days use the Warm Spell Duration Index (WSDI) - the WMO/ETCCDI-standard heatwave measure: days that are part of a run of 6 or more consecutive days above the local 90th-percentile temperature for that calendar day. The 90th-percentile threshold varies by time of year (a hot day in January is judged differently to one in July) but is fixed to the 1961-1990 baseline for every year shown - it does not shift as the climate warms, which is why Heatwave Days trend upward over time.
Does the South America climate page include frost and snow data?
Yes. Frost Days (days with a minimum temperature below 0°C, World Bank CCKP) and snow water-equivalent (GPCC) are shown alongside temperature and precipitation, each measured against the 1961-1990 baseline where a like-for-like historical comparison is available.
What major climate events has South America experienced?
Major climate events in South America include Brazil's 'black frost', 1975; Suriname's interior floods, 2006; Colombia's La Niña floods, 2010-11; São Paulo's water crisis, 2014-15; Peru's coastal El Niño, 2017; The Amazon drought of 2023-24; The Rio Grande do Sul floods of 2024. The Climate History panel on this page lists 52 sourced events and pattern shifts relevant to South America, the earliest from 1912 - 19 about South America itself and the rest global context such as volcanic eruptions and El Niño events. Each entry carries its own sources and can be searched, filtered to local events or by category, and sorted by date; scrolling the list moves a cursor across the chart above so you can see where each event falls in the record.
Where does the Climate History list for South America come from, and how is it checked?
It is a hand-reviewed register, not an automatic feed. Every entry is sourced, and each one records how it was verified - against this site's own data series, against a peer-reviewed paper, or against the public record of the event. The rest give global or national context shared with wider pages. Where a figure is narrower than it first appears, or a famous claim does not hold locally, the entry says so.
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