Luton has a temperate marine climate, like much of the British Isles, with generally light precipitation throughout the year. The weather is very changeable from day to day and the warming influence of the Gulf Stream makes the region mild for its latitude. The average total annual rainfall is 698 mm (27.5 in) with rain falling on 117 days of the year.
The local climate around Luton is differentiated somewhat from much of South East England due to its position in the Chiltern Hills, meaning it tends to be 1–2 degrees Celsius cooler than the surrounding towns – often flights at Luton airport, lying 160 m (525 ft) above sea level, will be suspended when marginal snow events occur, while airports at lower elevations, such as Heathrow, at 25 m (82 ft) above sea level, continue to function. An example of this is shown in the photograph to the right, the snowline being about 100 m (328 ft) above sea level. Absolute temperature extremes recorded at Rothamsted Research Station, 5 miles (8 km) south south east of Luton town centre and at a similar elevation range from −17.0 °C (1.4 °F) in December 1981 and −16.7 °C (1.9 °F) in January 1963 to 36.6 °C (97.9 °F) in July 2019 and 33.8 °C (92.8 °F) in August 1990 and July 2006. Records for Rothamsted date back to 1901.