UK September weather forecast: Met Office signals fresh warm spell as late-summer heat could return

The arrival of September may mark the beginning of meteorological autumn, but the UK’s warm weather may not be over yet.

The latest long-range outlook indicates that parts of Britain could experience further bursts of late-summer warmth during September, with London and southern England among the areas most likely to see short-lived warm or very warm spells.

While speculation has grown about the possibility of another official heatwave following one of the hottest summers in recent memory, the forecast does not guarantee a prolonged period of extreme temperatures. Instead, forecasters are pointing towards a more mixed weather pattern, with rain and unsettled conditions affecting some parts of the UK while warmer and drier intervals develop elsewhere.

The biggest chance of renewed warmth appears to be in southern and southeastern England, where high pressure could occasionally bring brighter and more settled conditions as September progresses.

Met Office Forecast Hints at Warm September Weather in Southern England

The long-range forecast suggests temperatures during the early part of September could remain close to seasonal averages across much of the UK.

However, the outlook includes an important possibility for southern areas: short-lived warm or very warm spells may develop, particularly across London and southern England.

That distinction is significant. A warm spell does not automatically mean the UK is heading for another heatwave.

The forecast allows for periods of above-average temperatures, but confidence remains limited regarding the timing, duration and intensity of any hotter conditions. Weather patterns can change rapidly at longer forecasting ranges, making it difficult to predict whether any warm spell will become prolonged enough to meet official heatwave criteria.

For people hoping summer temperatures will continue into September, the outlook offers encouragement, especially in the south. It does not, however, provide a guarantee of sustained heat.

Will the UK Get Another Heatwave in September?

The possibility of another UK heatwave in September 2026 remains open, but it is not the central forecast.

In London, an official heatwave requires temperatures to reach at least 28C for three consecutive days. The current outlook suggests southern England could experience temperatures warm enough to test that threshold if favourable weather patterns develop.

Still, the forecast stops short of predicting a confirmed heatwave.

The most likely scenario is a changeable start to September, followed by periods where high pressure brings warmer and drier weather to parts of southern England. Any stronger influx of continental air could push temperatures higher, potentially producing conditions that feel more like late summer than early autumn.

For now, forecasters are urging caution over headlines predicting a definite return to extreme heat.

UK Weather Forecast Shows North-South Divide for September

One of the clearest features of the September outlook is likely to be a northwest-southeast weather divide.

Low pressure is expected to remain more influential across northern parts of the UK, increasing the likelihood of wetter and windier conditions in Scotland, Northern Ireland and northwestern England.

Southern and southeastern England, meanwhile, could see a greater chance of drier interludes.

The weather pattern is expected to bring showers and longer periods of rain at times, particularly in northern and western regions. Southern areas may also experience rain during the opening part of September, but the prospect of more settled weather could increase later in the month.

This means the experience of September weather could vary considerably depending on location.

While some areas face frequent rain and cooler conditions, others could see sunshine and renewed warmth.

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London Weather Could Turn Very Warm Again

London remains one of the locations most likely to benefit from any late-summer temperature rise.

Forecast guidance has suggested the capital and surrounding areas could experience temperatures reaching the mid-20s Celsius during favourable periods in early September.

Temperatures at that level would provide a distinctly summery feel, even after meteorological autumn officially begins on September 1.

A stronger period of warm air from continental Europe could potentially push temperatures higher, though the current outlook does not establish when or whether such a pattern will develop.

The forecast therefore presents a mixed picture for London: residents may need jackets and umbrellas during unsettled periods, while sunscreen could still prove useful when warmer conditions return.

2026 Has Already Delivered Multiple UK Heatwaves

Any discussion about a possible September warm spell comes after an exceptionally hot summer.

The UK has already experienced several periods of significant heat during 2026, with Kew Gardens in west London reaching 38.1C, according to the source material.

Other locations also experienced temperatures of 37C or higher during the summer.

The prolonged hot and dry conditions placed additional pressure on water supplies and contributed to drought conditions across parts of England. July was also described as exceptionally dry for England and Wales.

Against that backdrop, even a relatively short warm spell in September could attract significant attention.

The longer-term outlook for the September-to-November period continues to suggest that warmer conditions remain possible, particularly during the earlier part of autumn. That outlook reflects an increased possibility of above-average warmth rather than a guarantee of persistent hot weather.

What to Expect From UK Weather in September

The most likely forecast is for September to begin with a mixture of sunshine, showers and longer spells of rain.

Northern and western parts of the UK could experience the most unsettled conditions, while southern and southeastern areas may increasingly benefit from drier and warmer intervals.

For London and much of southern England, late-summer warmth remains a realistic possibility.

However, anyone expecting a guaranteed sixth heatwave should remain cautious. The Met Office outlook leaves the door open to another period of very warm weather, but the development of an official heatwave will depend on how weather patterns evolve.

For now, the message is simple: summer-like temperatures could return to parts of the UK in September, but another major heatwave is far from certain.

Frequently Asked Questions About the UK September Weather Forecast

Will September be warm in the UK in 2026?

Parts of the UK could experience warm or very warm spells during September 2026. Southern and southeastern England, including London, currently have the greatest chance of seeing late-summer warmth.

Is another UK heatwave coming in September?

Another UK heatwave is possible, but the forecast does not guarantee one. Long-range guidance suggests short-lived warm spells could develop, particularly in southern England, but confidence remains limited over whether temperatures will meet official heatwave criteria.

What is the Met Office September weather forecast?

The outlook suggests mixed conditions during early September, with showers and longer periods of rain affecting some areas. Northern and western parts of the UK may experience wetter conditions, while southern England could see warmer and drier intervals.

Will London be hot in September?

London could experience periods of warm or very warm weather during September. Temperatures may rise into the mid-20s Celsius during favourable weather patterns, with higher temperatures possible if warmer continental air reaches the UK.

What temperature is needed for a heatwave in London?

According to the criteria referenced in the source material, London requires temperatures of 28C or above for three consecutive days for an official heatwave.

Which parts of the UK will be warmest in September?

Southern and southeastern England are expected to have the greatest chance of experiencing renewed warm weather. London and surrounding areas could benefit from warmer conditions when high pressure becomes established.

Will northern England and Scotland be wet in September?

Northern and western parts of the UK are more likely to experience unsettled weather under the current outlook. Scotland, Northern Ireland and northwestern England could see more rain and wind than southern regions.

Why has the UK been so hot in 2026?

The source material describes 2026 as a year that has already produced several major warm spells and heatwaves. The summer has also brought exceptionally high temperatures and dry conditions in parts of England and Wales.

Could the UK get temperatures above 30C in September?

The current long-range forecast does not guarantee temperatures above 30C. A stronger influx of warm continental air could increase temperatures significantly, but the available outlook does not confirm that such conditions will occur.

When will warm weather return to the UK?

The forecast suggests that warm spells could occur during September, especially in southern England. The precise timing and duration of any warmer period remain uncertain.

Should people expect rain in September 2026?

Yes. September is expected to begin with a mixed weather pattern, including showers and longer periods of rain. The north and west are more likely to experience unsettled conditions.

Will September feel like summer or autumn in the UK?

The answer may depend heavily on location. Northern and western areas could experience more autumn-like rain and wind, while southern England may still see periods that feel distinctly like late summer.