Plzeň has a central European continental climate — cold winters, warm summers, and the most reliable weather in spring and early autumn. July and August are pleasant but can hit 30°C; January and February bring frost and occasional snow, though the city functions normally year-round.
Spring (April–May) is the best time to visit: mild weather, long days, and the old town is not yet crowded. Autumn (September–October) is equally good, with lower prices than Prague and comfortable temperatures for walking.
The Plzeň Oktoberfest (late September) draws crowds to the Pilsner Urquell grounds for a long weekend of unfiltered beer and live music — fun, but book accommodation early. The Smetanova Plzeň classical music festival runs each spring. In December, the Republic Square hosts a Christmas market that is quieter and less commercial than Prague's.