The UK is not expected to have another official heatwave in September 2025. The weather forecast indicates more changeable and unsettled conditions with temperatures likely in the low twenties Celsius, which is warm but not reaching heatwave criteria. While there may be some warmer spells or an "Indian summer" feel, temperatures are not predicted to hit the sustained high levels required for a heatwave this month. Across parts of North America, however, unusually high temperatures and heatwaves have been observed in early September 2025.

UK Heatwave Outlook

• The UK experienced four heatwaves in summer 2025 but is transitioning to more typical autumn weather with showers and cooler temperatures.
• Heatwave criteria in the UK require sustained temperatures above local thresholds for three or more days; this is not forecast for September.
• Temperatures are expected to be around 17-22°C, with occasional rises up to the mid-twenties but not consistently hot enough for a heatwave.

Other Regions

• Western North America has seen a prolonged period of heat with temperatures reaching record highs early in September 2025.
• Some parts of England saw temperatures into the mid-20s and low 30s earlier in September, but these did not signify extended heatwaves for the month.

In summary, no major heatwave is forecast for September 2025 in the UK, though warm spells may occur. Other regions, especially in western North America, have experienced more intense heat during this period.