Following a period of unseasonably warm weather, the UK is bracing for a significant drop in temperatures that will bring the coldest night of autumn to date. Meteorologists indicate that Wednesday night will see the season’s first frost in certain locations as cold air masses from the Arctic sweep across the country.
By dawn on Thursday, minimum temperatures in some areas could hover just one or two degrees above freezing. While the sharp contrast to recent weeks will feel markedly colder, particularly in the south, readings are still expected to remain near or slightly below the seasonal average for this time of year.
The shift is being driven by a southerly displacement of the jet stream. For much of early autumn, the jet stream had remained positioned to the north of the UK, allowing mild south-westerly winds to keep southern regions several degrees above average. The south has been particularly warm, with temperatures exceeding 20C daily since June. However, as the jet stream sinks further south this week, northerly winds will introduce the frigid air mass.
Daytime highs on Wednesday are forecast to reach between 12C and 14C in Scotland and Northern Ireland, and 14C to 16C in England and Wales. Overnight lows are expected to range from 5C to 7C across most towns and cities, with rural areas in northern and eastern England and eastern Scotland potentially seeing temperatures close to freezing and light frost on grass and vehicles.
Besides the chill, the changing weather pattern will deliver vital rainfall to England and Wales. A frontal system moving eastward will bring persistent rain to eastern England and the far south-east on Wednesday, despite clearer spells returning to other areas. Southern and eastern England, regions that have experienced severe dryness, could receive 20 to 30mm of rain—equivalent to up to half a month’s typical precipitation—in a single day.
This rainfall is critical for areas still grappling with drought conditions. Nearly three-quarters of England and all of Wales remain under drought status, and the Environment Agency has stated that rainfall must exceed normal levels by 20% for at least seven months to lift these designations.
The bitter conditions are expected to ease by the end of the week. Thursday will remain chilly with maximums between 11C and 16C, though bright intervals may make afternoons feel pleasant. By Friday, westerly winds will reintroduce milder air, pushing temperatures back toward 20C in eastern areas, with no frost expected in the north.
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