London Faces Second Heatwave: 6 Days Over 30°C, Met Office Issues Extreme Warning

Second Heatwave Hits London with Six Days of 30°C+ Temperatures

London is set to endure another prolonged period of sweltering heat, with temperatures forecast to exceed 30°C for six consecutive days starting Monday, July 6. The BBC Weather forecast predicts highs of 31°C on July 6, rising to 32°C on July 8 and 9, before remaining at 31°C until July 11. The next day below 30°C is not expected until July 12.

A heatwave in London is defined as three consecutive days at 28°C or higher. According to the current forecast, temperatures will not drop below 28°C until July 18, though cloud cover and rain may provide some relief after July 11. While this heatwave may not reach the record-breaking 37°C seen in June, it will still be intense for residents.

Urban Heat Island Effect Amplifies Heat

London is particularly vulnerable to high temperatures due to the Urban Heat Island (UHI) effect, where dense buildings trap heat, making the city feel up to 10°C hotter than surrounding areas. This phenomenon has contributed to record-breaking temperatures in recent summers.

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The Met Office has classified the current conditions as a Category 2 marine heatwave, with sea-surface temperatures 1.5-4°C above normal in regions around the English and Welsh coastlines, the English Channel, and the central and southern North Sea. Sea temperatures range between 15°C and 19°C.

Potential for Category 4 Extreme Marine Heatwave

Dr Ségolène Berthou, Air-Sea Interaction Specialist at the Met Office, stated: “Marine heatwaves around the UK have developed rapidly following the recent heat dome, and we are now seeing widespread strong to locally severe conditions. This is the third and most intense marine heatwave we have seen this year.”

She added: “While these warmer seas did not significantly increase peak temperatures on land, they reduced night-time cooling and helped sustain warmth, particularly in coastal areas. With further sunny and calm weather likely next week, there will be little opportunity for the ocean to release this excess heat. This means the surface marine heatwave could intensify further, potentially reaching extreme levels in the south. Such conditions would be highly unusual for UK waters.”

A Category 4 marine heatwave is classified as “extreme” and has rarely been recorded in UK waters. Marine heatwaves can have significant impacts on ecosystems and wildlife.