When to come — and when to absolutely avoid
By season
Quietest: Mid-January to mid-March (excluding the lead-up to Easter) and the first three weeks of November — Prague in the off-season is cold, often with snow on the cathedral roof, but the interiors are wonderfully empty. Daylight is short, so plan a morning visit. Busiest: Late May through August (especially July), Easter weekend, the entire week between Christmas and New Year, and the Christmas markets period from late November to early January. Saturdays from April to October are always packed.
By day of the week
Tuesday and Wednesday mornings are calmest. Saturday is the worst day — local Czech families, weekend tourists and weekend tour groups overlap. Avoid Sunday before noon if St. Vitus Cathedral is a priority: it's closed for Mass until midday.
By time of day
The first hour after opening at 09:00 is the calmest of the entire day — coach tours typically arrive between 10:30 and 11:00, peak from 11:30 to 14:30, and thin out noticeably after 15:30. Late afternoon (16:00 onwards) and early winter mornings are the quietest single windows. The noon guard ceremony briefly fills the First Courtyard with onlookers, after which the rest of the complex empties out for around 30 minutes — a perfect time to walk into Golden Lane.