Brazil 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

How much ENSO really controls Brazil's climate

ENSO matters in Brazil, most of all in February-April: the El Niño-La Niña cycle explains about 30% of the year-to-year swing in Brazil's February-April rainfall, with El Niño years tending drier and La Niña years wetter. That puts Brazil among the 88 countries in this site's data where ENSO's influence is strong enough to be worth reporting.

NOAA CPC

Keeling Curve begins

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'.

NOAA GMLGreenhouse Gases

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

The 1973-74 La Niña

Brazil's rainfall for February-April 1974 ran +17% against its 1961-90 average - the wet February-April that La Niña usually brings here.

ONI -2.0°C · RONI -1.9°C

NOAA CPCENSO Tracker

Brazil's 'black frost', 1975

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.

Perfect Daily Grind, Uncommon Grounds

Pacific Decadal Oscillation flips to a warm phase

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.

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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

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.

ONI +2.1°C · RONI +2.4°C

NOAA CPC, NOAA CPC (2)ENSO Tracker

The Antarctic ozone hole is discovered

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.

Nature, UKRI

The Montreal Protocol

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.

NOAA, Wikipedia

CO₂ crosses 350 ppm

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.

NOAA GMLGreenhouse Gases

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

Mount Pinatubo erupts

Pinatubo's cooling does not show in Brazil's own record: 1992, the year after the June 1991 eruption, was an unremarkable year there, 32nd-coldest of 76. 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 - 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.

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1997-98 El Niño

Brazil's rainfall for February-April 1998 ran -12% against its 1961-90 average - the dry February-April that El Niño usually brings here. 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 - 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.

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2009-10 El Niño

2010 is Brazil's 8th-warmest year in this site's 1950-2025 record. The 2009-10 El Niño helped make 2010 the warmest year worldwide on record at the time.

ONI +1.5°C · RONI +1.5°C

NOAA/IRI ENSO archiveENSO Tracker

Global heatwave days sharply accelerate

Brazil's own heatwave days - days in warm spells well above the local norm - rose from a 1961-90 average of 4.4 a year to 19.9 in 2016-25 - 4 times as many. Worldwide, heatwave days have roughly doubled each decade since 2010, as the whole temperature distribution has shifted upwards.

Learn more →Heatwave Days

The 2010-2012 La Niña

Brazil's rainfall for February-April 2011 ran +13% against its 1961-90 average - the wet February-April that La Niña usually brings here.

ONI -1.6°C · RONI -1.6°C

NOAA CPC ONI

The Rio de Janeiro mountain floods, 2011

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.

NASA Earth Observatory, ReliefWeb

CO₂ crosses 400 ppm

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.

NOAA GMLGreenhouse Gases

São Paulo's water crisis, 2014-15

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.

World Weather Attribution, Hydrology

2015-16 El Niño

Brazil's rainfall for February-April 2016 ran -18% against its 1961-90 average - the dry February-April that El Niño usually brings here. 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. Brazil follows it closely: seven of its own eleven warmest fall in that span, with 2010, 2005, 2002 and 1998 outside. Its warmest year is 2024.

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COVID-19 lockdowns - CO₂ emissions dip

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.

Le Quéré et al. 2020

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

The Amazon drought of 2023-24

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.

Espinoza et al. 2024, NASA Earth Observatory

The Rio Grande do Sul floods of 2024

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.

World Weather Attribution, PAHO