London has a temperate climate. A temperate climate can be very unpredictable with erratic weather patterns that occur in summer as well as winter. However, London generally has warm but seldom hot summers and cool but rarely severe winters. It also has regular but generally light precipitation throughout the year. London ‘s average annual precipitation of less than 24 inches (600 mm) is lower than that of Rome.
Being a highly-urbanized area, London with its large built-up area creates a microclimate, with heat stored by the city’s buildings. A microclimate is a local external atmospheric zone where the climate differs from the surrounding area. At times temperatures are 5 (9 warmer in the city than in the surrounding areas. Summer temperatures rarely rise above 33 (91 though higher temperatures have become more common recently. The highest temperature ever recorded in London was 38.1 (100.6 measured at Kew Gardens during the European Heat Wave of 2003. Heavy snowfalls are almost unknown that in winters, snow has rarely settled to more than an inch (25 mm).