It’s not only Brits that sweltered through balmy conditions last month.
Globally, May 2025 was the second-hottest May on record, scientists at the the EU’s Copernicus Climate Change Service (C3S) reveal.
The global average air temperature for the month was 60.42°F (15.79°C), which is 0.95°F (0.53°C) above the 1991-2020 average for May.
The figure is just below the May record-holder, May 2024, which had a global average air temperature of 60.6°F (15.91°C).
Worryingly, experts point to human-cased greenhouse gas emissions as the cause for this latest temperature ‘anomaly’.
It comes after the second-warmest April on record, the second-warmest March on record, the third-warmest February on record, and the warmest January on record.
Meanwhile, summer 2024 was the hottest summer on record globally, while last year was the hottest year on record.
Going forward, 2025 could quite easily break these climate records.
May 2025 was the second-warmest May on record globally. This map shows where Earth suffered extremes in terms of heat last month, compared to the 1991-2020 reference period
This graph shows monthly global surface air temperature anomalies between January 1940 and May 2025 (in °C, relative to 1850–1900 average). Note that May 2024 was warmer than May 2025
Last month was the second-hottest May on record, experts reveal. Pictured, sunbathers in St James’s Park, London, May 1, 2025
Climate data like this 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.
Experts at CS3 – which is based in Bonn in Germany – reveal that last month was 2.52°F (1.40°C) above the May average for 1850-1900.
This 50-year period is the designated ‘pre-industrial’ reference period to which modern temperatures are compared.
The historical era was prior to widespread industrialization when humans started polluting the atmosphere and triggering global warming with the burning of fossil fuels.
According to the experts, of the last 22 months before May 2025, all but one (July 2024) had a global average temperature of more than 2.7°F/1.5°C above the pre-industrial level.
At 2.52°F/1.4°C above the pre-industrial average, May 2025 is also an exception to this pattern.
But experts think it won’t be long before 1.5°C is breached again.
Experts point to human-cased greenhouse gas emissions as the cause for this latest temperature ‘anomaly’. Most emissions come from burning fossil fuels such as coal for power. Pictured, a coal-fired power station in Newburgh, Indiana
As Britain sweltered though summer-like temperatures this spring, the new record for spring may not come as a surprise. Pictured, Greenwich Park, London, May 31, 2025
A young woman cools off amongst the water jets of a fountain during a hot spring day in Moscow, Russia, 26 May 2025
‘May 2025 breaks an unprecedentedly long sequence of months over 1.5ºC above [the] pre-industrial [average],’ said Carlo Buontempo, director of C3S.
‘Whilst this may offer a brief respite for the planet, we do expect the 1.5ºC threshold to be exceeded again in the near future due to the continued warming of the climate system.’
Looking at Europe specifically, the average temperature over European land for May 2025 was 55.36°F (12.98°C) – 0.29°C below the 1991-2020 average for May.
Generally, there were below-average temperatures in eastern Europe (such as in eastern Italy and Finland) and above-average temperatures in western Europe, including the UK which experienced weeks of balmy weather.
Outside Europe, temperatures were most above average over western Antarctica, Middle East and western Asia, northeastern Russia, and northern Canada.
But temperatures were particularly below average over India, Alaska, southern and northeast Africa, northern parts of Australia and eastern Antarctica.
Meanwhile, conditions were wetter than average across most of southern Europe, Scandinavia, the Baltic countries and in parts of western Russia.
Conversely, drier than average conditions were recorded in northern and central Europe as well as southern regions of Russia, Ukraine, and Turkey.
Britain just recorded its warmest and sunniest spring on record, going back to 1884. Pictured, students at the University of St Andrews take a dip, May 1, 2025
C3S also revealed that the global average sea surface temperature (SST) was 69.42°F (20.79°C) last month
The three months from March to May 2025 marked the second-warmest spring on record globally, according to CS3. These maps of Europe highlight anomalies for rain (left), surface soil moisture (centre) and river flow (right) between March-May 2025
The Met Office recently revealed that Britain recorded its warmest and sunniest spring on record, going back to 1884.
But globally-speaking, the three months from March to May marked the second-warmest spring on record, CS3 also reported. The global average temperature for spring 2025 was 0.59°C above the 1991-2020 average, behind only spring 2024.
Globally, March to May 2025 was drier than average over western North America and extra-tropical South America, the Horn of Africa, parts of central Asia, China, and south of Australia, CS3 added.
Wetter-than-average conditions were experienced over eastern North America, Alaska, across Russia, southern Africa, and northern Australia.
CS3’s main metric for measuring warmth is the temperature of the air, but it also keeps track of temperatures of the world’s oceans.
Namely it looks at sea surface temperature (SST) – how hot the water is at or close to the ocean’s surface, which can damage delicate marine ecosystems.
C3S said the global average sea surface temperature (SST) was 69.42°F (20.79°C) last month – 0.14°C below the May 2024 record.
Lastly, May 2025 saw Arctic sea ice 2 per cent below average, the ninth-lowest monthly extent for May in the 47-year satellite record.
Overall, the various indicators from CS3 once again suggest there are long-term changes happening to the global climate.
Carbon emissions and the greenhouse effect: A primer
The greenhouse effect is the reason our planet is getting too hot to live on.
CO2 released by human activity is accumulating as an ‘insulating blanket’ around the Earth, trapping more of the sun’s heat in our atmosphere.
Without the natural greenhouse effect, heat would pass outwards from the Earth¿s surface into space – making it too cold to live. But emissions of gases such as CO2 and methane push the greenhouse effect too far – acting as a blanket that traps heat
CO2 – and other greenhouse gases – are emitted by actions such as burning fossil fuels like coal for energy, burning forests to make way for livestock and
Fertilisers containing nitrogen produce nitrous oxide emissions – another greenhouse gas.
Meanwhile, fluorinated gases are emitted from equipment and products that use these gases.
Such emissions have a very strong warming effect, up to 23,000 times greater than CO2.
Sources: European Commission/BGS/NASA
