Summer 2021 in United States
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Summer Starts: Sunday, Jun 20 8:32 pm PDT
Summer Ends: Wednesday, Sep 22 12:21 pm PDT
Region: California/United States
Astronomical Summer Dates
The first day of summer (June solstice) is when the sun is in its most northern position directly over the Tropic of Cancer. This is referred to as astronomical summer or the summer solstice.
Astronomical summer starts at different times around the planet because of the different time zones as related to Coordinated Universal Time (UTC, same as Greenwich Mean Time based on the Royal Observatory in Greenwich, London [1]). For countries located west of UTC your summer will start earlier than countries located east of UTC.
Astronomical and Meteorological Summer
Astronomical Summer is determined by the changing positions of the earth relative to the sun giving us the solstices and equinoxes. Seasons are caused by the tilt of the earth on its axis by 23.5 degrees. The tilt of the earth does not change as it goes around the sun so in the Northern Hemisphere the earth is tilted toward the sun in June and away from the sun in December[2]. When the sun is over the equator you have the equinoxes and when the sun is over the Tropic of Cancer in the most northern position you have the summer solstice and conversely when the sun is over the most southern position over the Tropic of Capricorn you have the winter solstice. The summer solstice occurs in the Northern Hemisphere between the dates of June 20 to 22 followed by the September equinox - September 21 to 23 and then the Winter solstice - December 20 to 23 and finally the March equinox - March 19 to 21. The United States, most of North America, Europe and many countries in the Northern Hemisphere use astronomical summer to determine when summer season officially starts and ends.
Meteorological Summer is determined by the annual temperature cycles and the Gregorian calendar. Meteorological summer starts June 1st in the Northern Hemisphere and lasts 3 months (June, July, and August) with Autumn Season (September, October, and November) and Winter Season (December, January, and February) and finally Spring Season (March, April, and May). Australia and New Zealand in the Southern Hemisphere use meteorological summer thus the months of December, January, and February to determine their summer season.
Many countries around the world depending on their latitude will use different methods to determine the start of summer. Some of these methods are dependent on the longest day measured, cultural festivals, temperatures and traditional calendar systems. More of these timing methods to determine summer can be found on Wikipedia.org.
References:
1.”Greenwich Mean Time” - Wikipedia, wikipedia.org.
2.”Earths tilt and Seasons” - National Oceanic and Atmospheric Administration, noaa.gov.
| Summer | |
|---|---|
| Name(s): | Summer, Summer solstice, June solstice |
| Type: | Season |
| When: | Astronomical - Jun 20th to 22nd Meteorological - June, July, and August (Northern Hemisphere) |
Dates for Summer
| Year | Summer Starts | Summer Ends |
|---|---|---|
| Summer 2022 | Tuesday, June 21 2022 | Thursday, September 22 2022 |
| Summer 2023 | Wednesday, June 21 2023 | Friday, September 22 2023 |
| Summer 2024 | Thursday, June 20 2024 | Sunday, September 22 2024 |
| Summer 2025 | Friday, June 20 2025 | Monday, September 22 2025 |
| Summer 2026 | Sunday, June 21 2026 | Tuesday, September 22 2026 |
| Summer 2027 | Monday, June 21 2027 | Wednesday, September 22 2027 |