The heaviest tourist season runs April through September, with another peak around Christmas. Late spring is the time to see the Royal Parks and gardens at their freshest; fall brings autumnal beauty and fewer people. Summer gives the best chance of good weather, although the crowds are intense. Winter can be dismal—it’s dark by 5—but all the theaters, concerts, and exhibitions go full-speed ahead, and Christmas lights bring a touch of festive magic. Weather-wise, winter is cold and wet with occasional light snow and spring is colorful and fair. June to August can range from a total washout to a long hot summer and anything in between. Autumn, finally, ranges from warm to cool to mild. In short, layers and a brolly are your best friends. It's impossible to forecast London weather but you can be certain that it will not be what you expect.