Short Late‑September Heat Spell Forecast for Southern England

Overview

• Forecast maps and local models show a short run of very warm days emerging around September 24 with some southern areas possibly reaching about 29C.
• The Met Office frames the spell inside a wider forecast window from September 19 to 28 and says temperatures for the period will probably be close to average overall while allowing scope for some rather warm days.
• Counties most likely to see the highest daytime temperatures include Somerset, Berkshire and Wiltshire with parts of London, Surrey and Cambridgeshire also flagged to approach 29C.
• Forecasters stress uncertainty because the outlook is model‑based and changeable, noting there could be dry settled interludes, cooler nights that risk grass frost, and the chance settled weather may push north later in the period.
• The Met Office defines a heatwave as daily maximums at or above local thresholds for three consecutive days and south‑east thresholds sit around 26C–28C, so any official heatwave call will depend on whether those local benchmarks are met.