Two ways to define the start of the season
Both dates are valid; they refer to different season systems.
Astronomical Summer
Begins at the June solstice in the Northern Hemisphere.
Meteorological Summer
Begins on June 1 every year in the Northern Hemisphere.
Which date should you use? Use the astronomical date when you mean the solstice- or equinox-based season. Use the meteorological date when you mean the fixed three-month season used for weather and climate records.
When Does Summer Start?
Astronomical Summer begins on Monday, June 21, 2027 in the selected timezone. Meteorological Summer begins on Tuesday, June 1, 2027. The first follows the astronomical season boundary; the second uses the fixed meteorological calendar.
Season Date & Planning Details
Astronomical Summer uses the solstice- or equinox-based seasonal boundary. The meteorological alternative is shown in the comparison above.
This seasonal boundary is not a public holiday.
Astronomical Summer Calendar (2027-2035)
| Year | Date | Day | Days Left | Weekend? |
|---|---|---|---|---|
| 2027 | June 21 | Mon | 309 days | No |
| 2028 | June 20 | Tue | 674 days | No |
| 2029 | June 21 | Thu | 1040 days | No |
| 2030 | June 21 | Fri | 1405 days | No |
| 2031 | June 21 | Sat | 1770 days | Yes |
| 2032 | June 20 | Sun | 2135 days | Yes |
| 2033 | June 21 | Tue | 2501 days | No |
| 2034 | June 21 | Wed | 2866 days | No |
| 2035 | June 21 | Thu | 3231 days | No |
What is Start of Summer?
In the Northern Hemisphere, astronomical summer begins at the June solstice, when the Sun reaches its northernmost position in the yearly cycle. Meteorological summer uses fixed three-month periods instead and begins on June 1. The astronomical start can shift slightly from year to year, while the meteorological date stays the same.
Calendar note
The main countdown follows astronomical summer. The comparison date follows the meteorological definition, which treats June, July, and August as summer in the Northern Hemisphere.
Date variation note
The June solstice can fall on June 20, June 21, or June 22 depending on the year and time zone. The UTC date may differ from the local calendar date in some locations.
Regional note
These dates describe summer in the Northern Hemisphere. In the Southern Hemisphere, the June solstice marks the beginning of astronomical winter, and the seasonal calendar is reversed.
Weather note
A calendar season does not guarantee an immediate change in local weather. Temperatures and weather patterns vary by location and from year to year.
Frequently Asked Questions
When does summer start in 2027?
Astronomical summer begins on June 21, 2027 in UTC. Meteorological summer begins earlier, on June 1, 2027.
Why does summer have two different start dates?
Astronomical seasons are based on Earth’s position relative to the Sun, while meteorological seasons use fixed three-month periods for weather and climate records.
Is June 21 always the first day of summer?
No. The June solstice can occur on different calendar dates, most commonly June 20 or June 21, depending on the year and time zone.
When does meteorological summer begin?
Meteorological summer begins on June 1 every year in the Northern Hemisphere and runs through August 31.
Does summer begin on the same date everywhere?
The solstice occurs at the same moment worldwide, but the local calendar date can differ by time zone. The June solstice also begins winter rather than summer in the Southern Hemisphere.
More Upcoming Days
The astronomical countdown uses the selected timezone. The meteorological countdown uses its fixed calendar start date in the same timezone.