Climate in London
Temperatures in London are much milder than parts of Continental Europe that are on the same latitude. This is due to the Gulf Stream, which has a moderating effect on London’s climate. The best time to visit London is from May to September when temperatures range from mild to warm and days long enough to see much of the city.
The summer months of July and August are the peaks of the tourist season in London attracting both international and domestic visitors. Therefore, you may want to consider travelling outside these two months if you prefer not to be part of the tourist crowd. However, summer is still the best time of the year for visiting the city with its longer daylight hours. Remember, that the urban micro-climate in inner London can get hot and humid during the summer especially in the evenings.
Kew Gardens in July by David Iliff
Spring & Summer
Spring temperatures in London (March to May) increase from average highs of 11°C (52°F) in March to 18°C (64°C) in May. It can get wet in spring and expect for the occasional thunderstorms. Summer (June to August) is generally warm with occasional rain but sometimes it gets hot. Temperature highs range between 21°C (70°F) and 24°C (75°F) but there are days when temperatures pass above 25°C (77°F) and on occasions above 30°C (86°F).
Autumn & Winter
Autumn (September to November) begins to get cooler with average highs dropping from 20°C (68°F) in September to 11°C (52°F) by November. Winter (December to February) in London is chilly, frosty, wet and windy. There is not much temperature variation in winter with highs averaging around 8°C (46°F) lows around 2°C (36°F). Snow does occur occasionally when temperatures reach freezing point but more common in the outer parts of London in the north.
Autumn in London by Grim23
When to Visit London
London is a year round destination and the best time to visit depends on your preference. The prime tourist season is generally from May to August when the weather is warm and daylight hours long. Expect long queues, booked hotels and high priced airfares during the period. The weather is milder and daylight hours shorter in March-April and September-October but still attract tourists though hotel prices and airfares are not as sky high. The low season is from November to February with its chilly weather and short daylight hours. However, queues are short and you can get great deals on hotels and airfares during the period if you don't mind the weather.
Compare all the top travel sites in a single search for the best deals.