Forget the umbrella, pack only short sleeves in summer, and bring a good coat and scarf in winter. That's about the sum of the weather in Madrid, at 655 metres above sea level. In general it's a dry climate, with little rain throughout the year, and extremely hot summers change quickly into fairly cold winters. Spring and autumn go practically unnoticed, and locals get the feeling they're wearing flip-flops one day and boots the next.
Spring. Brief but intense, especially for allergy sufferers, spring is nevertheless the best time to visit the city, with temperatures around 18ºC and often higher than that when June rolls around. Parks and gardens are gloriously fresh and green again after the winter and the bars start dragging tables and chairs out onto their pavements, marking the start of the season of outdoor terraces. But it is spring, remember, and as is typical of the volatile season, warm and sunny days are sometimes followed by colder days and the occasional shower.
Summer. Oh, those summers in Madrid! If you find it's the only season when you can get away, don't miss your chance to visit, but you'll quickly understand why the locals tend to sneak off to the coast and cooler climes, as temps in the city frequently climb above 30ºC. Madrid is usually a sleepy town in August, and tourists often outnumber residents. There can also be summer storms in August with black skies and torrential showers soon giving way to scorching sunshine once again. Fountains, swimming pools and ponds are full of sweltering sightseers looking for relief.
Autumn. Autumn sees the return of milder temperatures, though September can still be warm. Coats tend to come out of the closet again in October and it's a good idea to keep an umbrella handy just in case. November sees the return of the cold weather in the city - the mercury rarely rises above 15ºC - and it rains more frequently. In December you need to start wearing gloves and a scarf.
Winter. Winters in Madrid tend to be cold and dry, with temperatures below 10ºC during the day and as low as 0ºC at night. Snow is unusual but can fall at the end of December and the beginning of January. Days are usually clear and it's a good time to visit the mountains around the city. If you visit Madrid in winter, don't fool yourself that 'sunny Spain' will be like a holiday in the southern hemisphere: be sure to pack warm clothes.