When to come — and when to absolutely avoid
By season
Quietest: Mid-November to mid-March (excluding the Christmas-market weeks). The Castle District gets a dusting of snow, the lights at night are extraordinary and the queues at both museums almost disappear. Cold (often -5°C in January) but the views are at their most cinematic.
Busiest: July and August, the Christmas-market weeks in early December, and Easter weekend. Saturdays from May to September the cobbled lanes can feel uncomfortably packed between 11:00 and 15:00. Avoid the 20 August national holiday (St Stephen's Day) unless you're there specifically for the fireworks over the Danube.
By day of the week
Tuesday and Wednesday are calmest in the museums. Mondays are great for the outdoor parts — the museums are closed, which keeps the crowds away, but the courtyards, the Turul and the views are all free anyway. Saturday afternoon is the busiest single slot of the week.
By time of day
The first museum slot at 10:00 and slots after 16:00 are noticeably quieter than the 11:00–14:00 peak. For photos and the views, the magic hour is sunset to one hour after sunset — Parliament across the river floodlights at dusk and the whole Pest skyline glows. Come back at 22:00 and you'll have an empty Lion Courtyard with the Danube lit up below.