Parts of the UK are set to experience unseasonably high temperatures today, Tuesday 29 September 2026, with the mercury expected to climb as high as 27°C (81°F) in London and the South East.
Met Office forecasters have described the late-September heat surge as “notable” and “unseasonable,” given that average temperatures for this time of year typically sit in the mid-teens. The spike is being driven by a low-pressure system in the Atlantic, which is acting as a pump to draw warm continental air from Europe across the British Isles.
While inland areas will see the highest peaks, coastal towns such as Bognor Regis will experience a more moderated version of the heat. According to official Met Office data, the forecast for Bognor Regis indicates a maximum temperature of approximately 20°C, providing a bright and warm afternoon for the West Sussex coast compared to the usual autumnal chill.
A brief summer return before rain
Stephen Dixon, a spokesperson for the Met Office, noted that the temperatures are particularly significant for the final days of September. However, the summer-like conditions are expected to be short-lived as a weather front approaches from the west.
The technical cause of the warmth—the Atlantic low-pressure system—will eventually bring a shift to more unsettled conditions. Heavy rain is forecast to arrive in western parts of the UK late on Tuesday evening. This rain front is expected to track eastwards across the country throughout Wednesday, bringing an end to the brief warm spell.
Residents in Bognor Regis can expect sunny spells to continue through the afternoon before cloud cover increases ahead of the rain expected to reach the South East by Wednesday morning. Winds are also forecast to strengthen as the transition to more traditional autumnal weather begins.