Countdown to
The First Day of Summer
The longest day, and summer's long light begins
Today is the First Day of Summer.
231 days until the First Day of Summer, on Monday, June 21, 2027.
The First Day of Summer is Monday, June 21, 2027. Happens the June (summer) solstice (computed astronomically, in UT).
The first day of summer is the year’s longest day in the Northern Hemisphere — the June solstice. Around June 20 or 21 the Sun climbs to its highest, most northern point in the sky, delivering more daylight than any other date and opening astronomical summer. From here the days, imperceptibly at first, begin to shorten again toward autumn.
It is the season’s starting line rather than its peak of heat: the longest day comes weeks before the warmest, because land and ocean take time to soak up the extra sunlight. The first day of summer marks the light, and the warmth follows.
How we get this date. The countdown is pinned to the exact instant of the June solstice, computed from Jean Meeus’s Astronomical Algorithms (Ch. 27) and given in Universal Time. Summer officially begins the moment the Sun reaches its farthest point north, standing directly overhead at the Tropic of Cancer. Because the calendar does not divide evenly into Earth’s orbit, that instant slips about six hours later each year and resets at every leap day, so the first day of summer falls on June 20 or 21 — and, very rarely, June 22 in some time zones.
Meteorologists mark it differently. Their summer runs June 1 through August 31, three whole months grouped to match the warm-weather cycle and simplify climate records — which is why forecasters are already calling it summer weeks before the astronomical first day arrives.
One quirk worth knowing: the longest day is not the year’s earliest sunrise or latest sunset. Because of Earth’s tilt and slightly elliptical orbit, the earliest sunrise comes a few days before the solstice and the latest sunset a few days after; only total daylight peaks exactly on the solstice.
A timezone note. The solstice is a single instant in Universal Time, so the first day of summer can land on different local dates. In years when the moment falls near midnight UT, the calendar reads June 20 across the Americas while it is already June 21 through Europe, Asia, and the Pacific. The instant is one; the date depends on where you stand.
Culturally the first day of summer is the season of long evenings, school holidays, and the outdoor calendar — Midsummer bonfires and maypoles across Scandinavia, dawn crowds among the stones at Stonehenge, and the United Nations’ International Day of Yoga, all tied to the solstice. However you keep it, it is the year’s high point of light and the gateway to summer’s long, warm evenings.
☀️ Fun facts about the First Day of Summer
- Meteorological summer runs June 1 through August 31, so forecasters count summer as beginning about three weeks before the astronomical first day set by the solstice.
- The first day of summer is the longest day of the year, but not the earliest sunrise or latest sunset — those fall a few days before and after the solstice because of Earth's tilt and elliptical orbit.
- At the June solstice the noon Sun stands directly overhead along the Tropic of Cancer, about 23.5 degrees north of the equator.
- North of the Arctic Circle the Sun never fully sets on the first day of summer — the midnight sun.
- In the Southern Hemisphere the same June solstice is the first day of winter, the shortest day of their year.
Upcoming First Day of Summer dates
| Date | Days away |
|---|---|
| 231 days | |
| 596 days | |
| 962 days | |
| 1,327 days | |
| 1,692 days |
How people mark the First Day of Summer
- Midsummer bonfires and maypole dancing
- Sunrise gatherings at Stonehenge
- Beach trips and the start of school holidays
- Late-evening cookouts in the long daylight
- Midnight sun festivals in the far north
Frequently asked
When is the first day of summer?
In the Northern Hemisphere it is the June solstice, which lands around June 20 or 21 each year (very rarely June 22 in some time zones). It is the day with the most daylight of the whole year.
How is the date calculated?
The countdown is pinned to the exact instant of the June solstice, computed from Jean Meeus's Astronomical Algorithms (Ch. 27) and given in Universal Time — the moment the Sun reaches its farthest point north.
Is the first day of summer the same as meteorological summer?
No. Meteorological summer always begins on June 1, grouping June, July, and August for climate records. Astronomical summer, which the countdown tracks, begins at the solstice about three weeks later.
Why isn't the first day of summer on the same date every year?
The calendar year does not divide evenly into Earth's orbit, so the solstice drifts about six hours later each year and resets at each leap day, landing on June 20 or 21.