Prague's Climate
Check any internet weather resource on the climate in Prague and it will tell something to the effect of “Prague lies in a temperate zone and has pleasantly mild Summers and Winters” but, trust us, they are going on long-term averages!
Yes, Prague is in a Temperate zone and has average temperatures of 18-19C in Summer and 0-4C in winter, but that is not what you will actually experience!
Prague Winters can drop to an exhilarating -20C (include wind-chill factor), and sometimes beyond. However, these days tend to very dry and can be wonderfully sunny – so wrap up warm and get out there – your face will feel alive for the experience. Most Prague residents at this abandon all sense of fashion and don multiple layers of clothing, even multiple coats.
Prague Summers are just the opposite, with temperatures sometimes soaring to 30C and beyond. The only way to deal with this is to find some shade – in a park, outside a bar or café – or go to the nearest swimming area or water park, of which there are many. Summer is also the time when Prague gets most of its annual rainfall, so be prepared for the occasional, though often refreshing, shower!
Spring and Autumn are probably more akin to the “pleasantly mild” description that other sites give. Though not necessary as wet as the Summer, they are usually a little cooler and probably more pleasant if you intend to visit every tourist attraction in a 4 day period. It’s probably worth carrying a light coat if you venture out into glorious sunshine but I wouldn’t bother with an umbrella, there’s always a handy bar or café to duck into.