Climatological averages, historical records, packing tips and best time to visit London during May. Met Office / ECMWF reanalysis 1991-2020.
Reference values based on 1991-2020 Met Office / ECMWF climatology. Year-to-year variation can be significant.
| Metric | Value | Date |
|---|---|---|
| All-time high | 40.2 °C | July 2022 |
| Heatwave record | 37.9 °C | August 2003 |
| All-time low | -13.2 °C | January 1962 |
| 24h rainfall | 75 mm | September 1968 |
Official records (Met Office). Secondary stations may have more extreme readings.
In May, London typically shows warmer days with parks in full bloom. The average high temperature is around 18°C and the average low around 9°C, with monthly rainfall of 46 mm spread over roughly 9 rain days and about 184 hours of sunshine. Average relative humidity stands at 71% and wind speed averages 14 km/h.
The local calendar in May is shaped by Chelsea Flower Show, so checking the forecast a few days in advance is worth it before any outdoor activity. Averages give a general picture but extreme events can vary widely: in May, London has recorded both unusually warm spells and cold incursions across recent decades.
For a typical stay we recommend t-shirt and light cardigan. UV protection is sensible on sunny days, even in a mild winter month, and a closed-toe waterproof shoe helps on damp days. For multi-day trips bring thin layers that you can combine through the day.
The first two weeks of May usually offer the best balance in London: moderate crowds, friendlier prices and weather that remains representative of the month. Late May starts showing features of the transition to the next month. Use our custom historical lookup to check the actual values for the exact year you plan to travel.
Of the twelve months, May is the 5th warmest in London and the 8th wettest. It collects 59 mm, 8 % of the whole year’s rain, spread over 11.1 days with appreciable precipitation. The warmest month is July and the wettest is October.
Among the 10 international cities with an ERA5-Land series on this site, in May London is the 9th warmest, with a mean maximum of 16.7 °C, and the 8th wettest. The wettest of them that month is New York, with 91 mm against London’s 59 mm.
ERA5-Land reanalysis from the Copernicus Climate Data Store (CC-BY licence), 30 complete years, 1995 to 2024. AEMET publishes normals for Spanish stations only, so the figures for London come from the global series. Sources and methodology → · Forecast for London →
