By Rick Steves and Gene Openshaw
July and August are London's peak season — my favorite time — with long days, the best weather, and the busiest schedule of tourist fun. Prices and crowds don't go up in summer as dramatically in Britain as they do in much of Europe, except for holidays and festivals. Still, travel during "shoulder season" (May, early June, September, and early October) is easier and can be a bit less expensive. Shoulder-season travelers usually enjoy smaller crowds, decent weather, and the full range of sights and tourist fun spots.
Winter travelers find fewer crowds and soft room prices, but shorter sightseeing hours. The weather can be cold and dreary, and nightfall draws the shades on sightseeing well before dinnertime. While England's rural charm falls with the leaves, London sightseeing is fine in the winter, and is especially popular during the Christmas season.
Plan for rain no matter when you go. Just keep traveling and take full advantage of "bright spells." The weather can change several times a day, but rarely is it extreme. As the locals say, "There's no bad weather, only inappropriate clothing." Bring a jacket, and dress in layers. Temperatures below 32°F make headlines, and days that break 80°F — while more common in recent years — are still infrequent in London. Weatherwise, July and August are not much better than shoulder months. May and June can be lovely. While sunshine may be rare, summer days are very long. The midsummer sun is up from 6:30 to 22:30. It's not uncommon to have a gray day, eat dinner, and enjoy hours of sunshine afterward.
Gene Openshaw is the co-author of the Rick Steves London guidebook.