Overview

• Temperatures reached 20.6°C in Northolt, west London, making March 20, 2025, the hottest day of the year so far in the UK.
• The warm weather coincides with the spring equinox, marking the start of astronomical spring in the northern hemisphere.
• A high air pollution alert has been issued for London due to increased particulate pollutants from mainland Europe.
• Warnings have been raised for allergy sufferers as birch pollen levels are high due to the early start of the pollen season.
• The warm spell is expected to end soon, with rain and unsettled weather forecast to arrive by Friday and persist through the weekend.