Unusual high heat Hits the U.K. in April
An early and intense heat is sweeping across the United Kingdom, bringing near-record temperatures to many areas even before the start of summer. Between April 27 and April 30, cities like Middlesbrough, Leeds, and Newcastle are seeing temperatures soar more than 8°C above what is normal for this time of year.
This sudden heat follows the fourth-warmest London Marathon on April 27, when runners battled temperatures of around 22°C — far above typical spring conditions. Forecasters now predict highs of up to 28–29°C to end the month, a level usually seen in mid-summer.
What makes this heat even more alarming is how much climate change is increasing its likelihood. New data from Climate Central reveals that the recent temperatures in parts of the U.K. are five times more likely to happen because of human-caused climate change.
Climate Change’s Clear Fingerprint
To help understand how much global warming is affecting our daily lives, scientists use something called the Climate Shift Index (CSI). This index shows how much more likely a weather event is because of climate change. A CSI level 5, the highest rating, means the heat is at least five times more likely to happen because of human actions like burning fossil fuels.
Between April 29–30, several cities in North and Central U.K. experienced extreme heat, reaching Climate Shift Index (CSI) level 5. CSI level 5 means the event is highly unusual and strongly influenced by human-caused climate change.
This marks a significant climate-linked weather event for spring 2025.
Here are some of the top temperature changes seen on April 30:
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Middlesbrough: 8.4°C above normal (CSI 5)
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Newcastle: 7.6°C above normal (CSI 5)
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Blackpool: 6.8°C above normal (CSI 5)
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Aberdeen: 4.1°C above normal (CSI 5)
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Plymouth: 3.4°C above normal (CSI 5)
Other cities like Leeds (8.4°C), Belfast (6.2°C), and London (5.1°C) also saw unusually high temperatures, with CSI levels ranging from 2 to 4.
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Over this short period from April 27 to 30, about 6.4 million people in the U.K. were exposed to at least one day of CSI level 5 heat. Meanwhile, 42 million people — that’s 61% of the entire U.K. population — experienced or will experience at least one day of heat made three times more likely by climate change.
Health and Environmental Impacts
This sudden burst of heat is doing more than just making people sweat. It’s already having visible effects on daily life and raising health concerns.
The London Marathon on April 27 was the fourth-warmest in its history, with over 56,000 runners taking part. Even though it only reached CSI level 1, that still means climate change played a small but real role in making the day hotter than normal.
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But the bigger issue is what these soaring spring temperatures can do to people’s health. In the U.K., heat-related deaths tend to rise when temperatures approach 29°C. This makes the current warm spell — arriving so early in the year — a serious health concern.
There are also other side effects. The early heat is causing very high pollen levels, especially in southern England and London. For people with allergies or asthma, this can make daily activities much harder.
Spring Heat in the U K Signals a New Climate Reality
Spring is already the fastest-warming season in the U.K., and this April’s heat shows just how far things have shifted. This isn’t what spring used to feel like. Many people expect warm weather in July or August, but not at the end of April.
Spring 2025 has brought unusually extreme heat to the U.K., a clear sign of climate change. Scientists link this landmark weather event directly to human activity.
Stay updated on heat conditions in your area by checking tools like the Global Climate Shift Index map, which tracks how much climate change is affecting daily temperatures.
