Last month was the third-hottest September on RECORD - with average global temperatures hitting a balmy 16.11°C

Brits endured mild and wet weather this September – but globally, the picture was a lot warmer.

Last month was the third-hottest September on record, scientists at the EU's Copernicus Climate Change Service (C3S) have revealed. 

The global average air temperature for the month was 16.11°C (60.99°F), which is 0.66°C (1.18°F) above the 1991-2020 average for September. 

Worryingly, the new figure is just below the September record-holder from two years ago – a global average air temperature of 16.38°C (61.48°F). 

Experts point to human-caused greenhouse gas emissions as the cause for last month's conditions, which also saw heavy rainfall and flooding in Europe. 

Samantha Burgess, deputy director of C3S, said the the 'global temperature context remains much the same' one year on from the second-hottest September. 

'The global temperature in September 2025 was the third warmest on record, nearly as high as in September 2024, less than a tenth of a degree cooler,' she said. 

'Persistently high land and sea surface temperatures [reflects] the continuing influence of greenhouse gas accumulation in the atmosphere.' 

It comes after the world sweltered through its third-warmest August, third-warmest July, third-warmest June and second-warmest May on record. 

2024 was the warmest year on record globally – with an average global air temperature of 15.1°C (59.18°F).

But as greenhouse gases like CO2 continue to accumulate in the atmosphere, 2025 could beat this record. 

According to C3S, which is based in Bonn, Germany, last month was the third-hottest September since records began in the 1940s.

Last month was also 1.47°C (2.64°F) above the September average for 1850-1900. 

This is the designated 'pre-industrial' reference period to which modern temperatures are compared – and suggests humans are to blame for a long-term warming trend. 

September 2025 was 0.27°C (0.48°F) below the warmest September on record (in 2023) and 0.07°C (0.125°F) cooler than the second-warmest September (in 2024).

What's more, the 10 hottest Septembers on record were all in the last 11 years. 

According to CS3, the 12‑month average temperature from October 2024 to September 2025 was 0.63°C (1.13°F) above the 1991–2020 average and 1.51°C (2.71°F) above the pre‑industrial level.

This slightly exceeds the threshold set by the Paris Agreement, the legally binding international treaty on climate change signed a decade ago.

Climate data like CS3's is collected using billions of measurements from satellites, ships, aircraft and weather stations around the world. 

Readings refer to the average air temperature for the whole planet over the whole month – so lower than a single typically 'hot' temperature reading. 

For example, 35°C (95°F) in any one location is considered dangerously hot to human life. 

In comparison, 16°C (60°F) feels mild in any one location, but as a monthly average for the whole world it is worryingly high.

Laura Tobin, meteorologist at Good Morning Britain, said 'you'd be right' if it didn't feel particularly hot in the UK to you last month – but globally it was a warm one.

'Last month was a cool one [in the UK], but actually it was the first time we've had below average temperatures since January,' she said. 'We say a warmer world because of fossil fuels causes more extreme weather events.' 

Looking at Europe specifically, the average temperature over European land last month was 15.95°C (60.71°F) – 1.23°C below the 1991-2020 average for September. 

CS3 said there were especially pronounced above-average air temperatures over Scandinavia and eastern Europe, while cooler-than-average temperatures – typically less than one degree below average – were observed only over parts of western Europe. 

Outside Europe, temperatures were higher than average over Canada, parts of Greenland, northwestern Siberia and large parts of Antarctica, but below average over northern central Siberia, western Australia and eastern Antarctica.

Meanwhile, conditions were wetter than average across much of northwestern and central Europe, including widespread rainfall in eastern France, western Germany, Belgium and Luxembourg. 

Heavy precipitation also caused flooding in some areas, such as southern Norway and northern Italy, causing catastrophic flooding and turning roads into rivers. 

Wetter-than-average conditions were also seen in southwestern and central US, Alaska, northwestern Mexico, southernmost Brazil, Argentina and Chile, the Northern Horn of Africa, the southern Arabian Peninsula, central Asia, eastern China and Pakistan and northern India, where millions were displaced by severe flooding. 

Conversely, drier than average conditions were recorded over most of the Iberian Peninsula, the Norwegian coast, much of Italy, the Balkans, and parts of Ukraine and western Russia.

Overall, last month's global surface air and sea surface temperatures (SST) – how hot the water is close to the ocean's surface – were both the third-warmest for September. C3S said the global SST was 20.72°C (69.29°F) last month, around 0.20°C below the September 2023 record – another metric suggesting an ongoing long-term warming trend. 

Lastly, Arctic sea ice last month was 2.2 million sq miles (5.07 million sq km), the 14th-lowest minimum in the satellite record, CS3 said. 

Arctic sea ice reaches its minimum extent during the northern hemisphere's summer before gradually getting larger until the winter as temperatures drop.

But unusually low ice coverage in the region for this time of suggests that summer temperatures are even higher than normal. 

In the UK, September 2025 was was a 'notably wet month' for many with a balance of warm and cool spells and sunshine slightly above the average for most, according to the Met Office.

September 2025 brought a change from the settled and warm conditions that characterised much of the UK's summer, which was named the hottest on record.