The Weather -- Yes, it rains, but you'll rarely get a true downpour -- it's heaviest in November (2 1/2 in. on average). British temperatures can range from 30° to 110°F (-1°-43°C), but they rarely drop below 35°F (2°C) or go above 78°F (26°C). Evenings are cool, even in summer. Note that the British, who consider chilliness to be wholesome, like to keep the thermostats about 10° below the American comfort level. Hotels have central heating systems, which are usually kept just above the goose bump (in Britspeak, "goose pimple") margin.
When You'll Find Bargains -- In short, spring offers the countryside at its greenest, autumn brings the bright colors of the northern moorlands, and summer's warmer weather gives rise to the many outdoor music and theater festivals. But winter offers savings across the board and a chance to see Britons going about their everyday lives largely unhindered by tourist invasions.
The cheapest time to travel to Britain is during the off season: from November 1 to December 12 and from December 25 to March 14. In the last few years, the airlines have offered irresistible fares during these periods. Remember that weekday flights are cheaper than weekend fares (often by 10% or more).
Rates generally increase between March 14 and June 5, then hit their peak in high travel seasons between June 6 and September 30 and December 13 and 24. July and August are also when most Britons take their holidays, so besides higher prices, you'll have to deal with crowds and limited availability of accommodations.
You can avoid crowds by planning trips for November or January through March. Sure, it may be rainy and cold -- but England doesn't shut down when the tourists leave! In fact, the winter season includes some of London's best theater, opera, ballet, and classical music offerings and gives visitors a more honest view of English life. Additionally, many hotel prices drop by 20%, and cheaper accommodations offer weekly rates (unheard of during peak travel times). By arriving after the winter holidays, you can also take advantage of post-Christmas sales to buy your fill of woolens, china, crystal, silver, fashion clothing, handicrafts, and curios.
Holidays -- Britain observes New Year's Day, Good Friday, Easter Monday, May Day (first Mon in May), spring and summer bank holidays (the last Mon in May and Aug, respectively), Christmas Day, and Boxing Day (Dec 26).
