Why Czechia rewards careful timing.
The Czech Republic is central Europe's most concentrated tourism circuit, Prague to Karlovy Vary 2h, Prague to Český Krumlov 3h, Prague to Brno 2h30, Prague to Bohemian Switzerland 1.5h. You can build a full 1-week trip without leaving the country, and add one neighboring country (Germany, Poland, Austria) without major train logistics.
Three regions, one calendar. Bohemia (the western half, including Prague, Karlovy Vary, Český Krumlov, Plzeň, Bohemian Switzerland) runs on continental-temperate climate, cold winters (-3 to 2°C), warm summers (18–28°C with regular 30°C+ heatwaves now), four distinct seasons. Moravia (the eastern half, including Brno, Olomouc, the wine country) runs slightly warmer than Bohemia in summer, slightly drier overall. Silesia (the small northern strip, including Ostrava) is the country's industrial heart, less tourist-relevant.
The Czech climate has unusually pleasant shoulder seasons. Spring runs late-April through June; autumn from early September through late October. May is the country's loveliest month, apple blossoms in orchards, fresh asparagus on menus, beer gardens opening, and the Czech Beer Festival (mid-May, in Letná Park, Prague) celebrating 70+ regional breweries. October brings vineyard harvests in Moravia (the country's wine heartland) and foliage in Bohemian Switzerland's sandstone forests.
Prague's December tourism boom is now the country's defining seasonal rhythm. Christmas markets open the first weekend after November 24 (typically late November) and run through January 6 in Prague's Old Town Square and Wenceslas Square. December has overtaken July–August as the busiest month, book Prague hotels 4+ months ahead for the first three weeks. Outside Prague, December is meaningfully quieter, Brno, Olomouc, and Český Krumlov all have their own lovely Christmas markets at half the crowds and prices.
The Czech Republic is the cheapest major Western European destination. Mid-range Prague hotels run €68–90/night in shoulder season; €100–150 during Christmas markets and summer peaks. Beer at a pub is €1.50–3 for a half-liter, about a third the price of comparable beers in Munich or Vienna. Restaurant dinners at traditional Czech places run €15–25 per person. Regional cities (Brno, Olomouc, Plzeň, České Budějovice) are 10–15% cheaper than Prague.
The country uses the Czech Crown (Kč/CZK), not euro, despite EU membership. Most Prague tourist-facing businesses accept euro at unfavorable conversion rates (8–12% loss); pay in crowns, especially via card, for the best rate. ATMs at non-bank locations (Euronet specifically) routinely rip off tourists with 10–15% effective exchange margins; use bank ATMs (ČSOB, Komerční Banka, Česká Spořitelna) only.