What the hottest summer on record means for the upcoming storm season

The United Kingdom has “almost certainly” experienced its hottest summer on record, according to provisional data from the Met Office, and the ripple effects could make the upcoming storm season significantly more dangerous. 

One of the most critical effects of the extreme heat we’ve been experienced is its ability to increase the amount of moisture the atmosphere can hold. Warmer air retains more water vapour, and when storm systems form, they are capable of unleashing this moisture in short, intense bursts. This means heavier downpours, more frequent flash floods, and a greater risk to areas with ageing or insufficient drainage infrastructure. 

Additionally, hotter conditions also destabilise the atmosphere, making extreme weather events more frequent and intense. In coastal regions, higher sea surface temperatures can supercharge storm systems coming off the Atlantic, making autumn and winter storms stronger and wetter. 

Another concern is the dry, compacted ground left behind by long hot spells. When heavy rain does arrive, the soil struggles to absorb it, causing water to pool on the surface and leading to surface water flooding, especially in built-up areas. 

This year’s record-breaking summer isn’t just a heat story, it’s a warning. With climate and weather systems becoming more volatile, the UK must prepare for more intense storm seasons, increased flooding, and greater strain on infrastructure. 

Vivian Camacho-Suarez, Flood Modelling Manager at Previsico said: “We tend to think of heatwaves and flooding as separate risks, but in reality, they’re deeply connected. The extreme heat we’ve seen this summer has primed the environment for more dangerous flooding, from hard, compacted soils that can't absorb rainfall, to warmer seas and atmosphere that supercharge storm systems. We need to start planning for a future where these kinds of compound events become the norm, not the exception.”