The main season runs from October to April, corresponding to the southern hemisphere spring and summer. Days are long — in December, Ushuaia gets around 17 hours of daylight — and temperatures are cool but manageable, rarely exceeding 15°C in midsummer. Rain is possible at any time of year.
Peak season is December and January, when the national park is at its most accessible, penguin colonies are active, and Antarctic cruises are departing regularly. This is also when prices are highest and accommodation needs booking well in advance. Last-minute Antarctic berths may be available from agencies in town, but the best prices require planning months ahead.
November and March offer good conditions with slightly fewer crowds and better value. Winter (May–September) brings snow, short days, and skiing on the Martial mountains. Some national park trails may be closed or very muddy, but the landscape takes on a different, starker beauty and the town is quieter.