Summer Solstice 2023 and 2024: When Does Summer Start?
The summer solstice marks the start of summer. In the Northern Hemisphere, the summer solstice is in June; south of the equator, it is in December.
Summer 2023 and 2024 Dates
Summer Solstice, Northern Hemisphere (June)
North America, Europe, most of Asia, Northern Africa
In Washington DC, District of Columbia, USA: Thursday, June 20, 2024 at 4:50 pm EDT (Change location)
This corresponds to Thursday, June 20, 2024 at 20:50 UTC.
Summer Solstice, Southern Hemisphere (December)
Australia, New Zealand, South America, southern Africa
In Washington DC, District of Columbia, USA: Thursday, December 21, 2023 at 10:27 pm EST (Change location)
This corresponds to Friday, December 22, 2023 at 03:27 UTC.
Alternative Summer Start Dates
Meteorologists use a different method of defining the first day of summer. And, in some countries, the beginning of the seasons is determined by average temperatures rather than fixed dates or astronomical events.
Days Get Shorter During Summer
Astronomical summer begins at the summer solstice, which is the longest day of the year. This means days get shorter during summer—very slowly at first, but at ever-larger daily intervals as the September equinox approaches, heralding the start of fall.
Locations closer to the poles experience larger differences in day length throughout the year, so summer days are longer there. In Toronto, the longest day is just over 15 hours and 26 minutes long; in Miami, roughly 2000 kilometers or 1200 miles farther south, it lasts about 13 hours and 45 minutes.
Places within the polar circles experience Midnight Sun or polar day during all or part of the summer season when the Sun does not set at all.
Shorter Days, but Rising Temperatures
Although daylight hours decrease during the summer months, temperatures continue to rise in most regions. This is because it takes time for Earth, particularly its oceans, to change temperature—an effect known as seasonal lag. (As a comparison, the planet Mars has seasons but no oceans, so there is almost no seasonal lag.).
Summer Traditions and Folklore
The start of summer and the summer solstice are celebrated in cultures and religions around the world with various traditions, holidays, and festivals.
In the Northern Hemisphere, astronomical and meteorological summer runs from June to September. South of the equator, it starts in December and ends in March. Read more about the history and meaning of the summer months:
Northern summer months
Southern summer months
How Long Is Summer?
The Earth does not move at a constant speed in its elliptical orbit, so the seasons are not of equal length. On average, summer lasts for 93.6 days in the Northern Hemisphere and 89.0 days in the Southern Hemisphere.
Average season lengths: