A heatwave is a continuous period of extremely warm weather.
The current UK heatwave has produced the hottest day in June for 41 years. A temperature of 34.5C at Heathrow on June 21st – appropriately Midsummer Day – almost matched the record of 35.6C set in June 1976.
This four-day heatwave now looks likely to end with thunderstorms as over the UK cooler air from the Atlantic meets hot air from southern Europe.
a continuous period of very hot weather, especially when this is unusual