Temperatures will climb across the UK this weekend, reaching summer-like conditions in several regions, though the warmth will fall short of heatwave thresholds and cooler air is expected to return by midweek.
The period will bring a combination of warm, humid conditions alongside heavy rain in places. While the warmth will extend into Monday across many areas, forecasters say no part of the country is expected to meet the criteria for an official heatwave. According to the latest BBC forecast, fresher Atlantic air and rain-bearing fronts will arrive through the following week, making a return to heatwave conditions unlikely over the next 10 days.
Computer weather models present a highly variable picture for the remainder of September, with some warm spells possible but currently no definitive indicators pointing to a sustained heatwave developing.
How warm will it get this weekend?
Rain will spread southwards on Saturday, clearing from Scotland and Northern Ireland but persisting into the afternoon across parts of northern England, Wales and the Midlands. Some rainfall could be heavy with a risk of thunder and lightning, accompanied by strong south-westerly winds.
Southern England is forecast to remain largely dry with sunny intervals, where conditions will feel particularly warm and humid. The warm spell is being driven by hot air spreading north from central and southern Europe, with southern and southeastern England most likely to see low- to mid-20s Celsius and isolated 27-28C readings in some locations. This represents several degrees above the typical mid-September average.
On Sunday, any lingering rain in southern England should clear, allowing a dry afternoon across much of the UK with sunny spells and light winds. Temperatures may ease slightly in the northern half of the country but could rise further south, with parts of Wales, the Midlands and southern England potentially reaching 23-25C.
Monday could bring even warmer conditions, with highs of 22-26C expected across much of England and Wales, and around 20C likely in parts of Scotland and Northern Ireland. Despite this warmth, temperatures will remain below the threshold required for an official heatwave.
A heatwave requires three consecutive days of temperatures exceeding a threshold that varies geographically—25C in Scotland and Northern Ireland, rising to 28C in the London area. The current forecast shows no such sustained period meeting these criteria.
What does the longer-range outlook show?
Computer models currently indicate unsettled weather will persist over the coming week or so. The jet stream is expected to direct areas of low pressure across the UK, bringing spells of rain and potentially blustery winds. This wet pattern will provide relief to large areas of England and Wales that remain affected by drought conditions.
Later in September, areas of high pressure may exert greater influence on the weather pattern, potentially allowing for longer dry periods and the possibility of above-average daytime temperatures. However, long-range forecasting carries significant uncertainty and details remain subject to change. The Met Office's broader September outlook still points to temperatures being around average overall, with brief warm or very warm spells possible, especially in the south.
Currently, there is nothing in the forecasts to suggest a heatwave is developing. Indeed, as autumn progresses and nights lengthen, high pressure overhead could lead to some notably chilly mornings, particularly in northern regions.
What happens next?
The outlook for the next 10 days shows fresher Atlantic air expected to arrive through next week, with heatwave conditions remaining unlikely during this period. Readers can monitor local temperatures by checking weather forecasts online.
Key Facts:
- Weekend temperatures will reach 23-25C on Sunday and 22-26C on Monday across southern regions, but will not meet heatwave criteria
- A heatwave requires three consecutive days above 25C in Scotland and Northern Ireland or 28C in London
- Unsettled weather with rain and strong winds is expected from mid-week onwards
- Later September may bring above-average temperatures but with significant uncertainty in long-range forecasts
- Drought-affected areas of England and Wales will benefit from the incoming wet weather
