Summer 2026 in the Southern Hemisphere begins on Monday, December 21, 2026 with the summer solstice: the longest day of the year, when the Sun reaches its highest point over the Tropic of Capricorn. It’s the moment when Argentina, Chile, Uruguay, Paraguay and southern Brazil welcome the most awaited season.
How long until summer starts? The exact countdown:
Time left until the start of summer 2026:
What is the summer solstice?
The solstice happens when the Earth’s axis is tilted 23.5 degrees with the Sun directly over the Tropic of Capricorn. That day, the Southern Hemisphere receives the most sunlight of the year: more than 14 hours of daylight in Buenos Aires and Santiago.
- Summer solstice (south): December 21, 2026.
- Winter solstice (south): June 21, 2027.
- In the Northern Hemisphere it’s the opposite: their winter starts exactly when our summer does.
Why the 21st or the 22nd?
The solstice can fall on December 20, 21 or 22 depending on the year, because the solar calendar (365 days) doesn’t exactly match the astronomical year (365.25 days). In 2026 it falls on December 21.
What happens in Southern Hemisphere countries?
- Argentina: summer vacations and year-end celebrations start, with 14-hour days.
- Chile: December 21 marks the Mapuche We Tripantu and the start of the summer season.
- Uruguay and Paraguay: beach season and domestic tourism kick off.
- Brazil: coastal cities fill up as the holidays approach.
Frequently asked questions
When is the first day of summer 2026? December 21, 2026 in the Southern Hemisphere (June 21 in the Northern Hemisphere).
How long does summer last? Until the March equinox: around March 20, 2027.
More seasons and dates: What’s celebrated today?, Christmas, New Year and Back to school.