Climate of the United Kingdom

London has a temperate marine climate (Köppen climate classification Cfb), like much of the British Isles, so the city rarely sees extremely high or low temperatures. Summers are warm with a July high of 22.8 °C (73.0 °F) and low of 14.0 °C (57.2 °F).[92] But temperatures can exceed 25 °C (77 °F) on many days, and in almost every year they exceed 30 °C (86 °F) on some days. The highest temperature ever recorded was 38 °C (100 °F) [93] on 10 August 2003 during the 2003 European heat wave.

Winters in London are chilly, but rarely below freezing (although in recent years this has been questionable) with daytime highs around 5 °C (41 °F) – 8 °C (46 °F), while spring has mild days and cool evenings.[93] The lowest ever recorded temperature was −21.1 °C (−6 °F) in January 1795. Autumn is usually mild but often unsettled as colder air from the arctic and warmer air from the tropics meet. London is a relatively dry city with regular but generally light precipitation throughout the year, with an average of 583.6 millimetres (22.98 in) every year. This is lower than many cities such as New York, Paris, Sydney and around the same as Jerusalem and San Francisco.

London receives an average of only 1461 hours of sunshine every year.[92]

Snow is relatively uncommon, particularly because heat from the urban area can make London up to 5 °C (9 °F) warmer than the surrounding areas in winter. Some snowfall, however, is usually seen up to a few times a year. The February 2009 Great Britain and Ireland snowfall was the heaviest London had seen for 18 years.

London is in USDA Hardiness zone 9, and AHS Heat Zone 2.[94] Although extreme weather does not happen very often, deep depressions have been known to pass through like the Great Storm of 1987. Tornados are rare, but the Kensal Green area of the city was hit by the 2006 London tornado causing £10 million of damage and injuring 6 people.

In the second half of the 19th century and the first half of the 20th, London was noted for its dense fogs and smogs. Following the deadly Great Smog of 1952, the Clean Air Act 1956 was passed, leading to the decline of such severe pollution in the capital.[95] In 2010, the City of London was ranked as one of the most polluted places in Europe

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