Summer Solstice Day

The Summer Solstice Day tool finds the exact date and UTC time of the summer solstice for any year from 2000 to 2099. It supports both Northern and Southern Hemisphere calculations, shows a live countdown to the next solstice, and provides multi-year comparison tables along with astronomical context.

What Is the Summer Solstice?

The summer solstice (also called the estival solstice or midsummer) is the astronomical event when the Sun reaches its highest position in the sky as seen from one of Earth's poles. It produces the longest day and shortest night of the year for that hemisphere.

• Northern Hemisphere: The summer solstice occurs around June 20-21 each year. The Sun is directly overhead at the Tropic of Cancer (23.44°N).
• Southern Hemisphere: The summer solstice occurs around December 21-22. The Sun is directly overhead at the Tropic of Capricorn (23.44°S).

What Causes the Solstice?

Earth's rotational axis is tilted at approximately 23.44 degrees relative to its orbital plane around the Sun. As Earth orbits the Sun over the course of a year, the orientation of this tilt relative to the Sun changes:

1. At the June solstice, Earth's North Pole is tilted maximally toward the Sun.
2. At the December solstice, Earth's South Pole is tilted maximally toward the Sun.
3. At the equinoxes (March and September), neither pole is tilted toward the Sun, and day and night are approximately equal.

How Long Is the Longest Day?

The length of the longest day depends on your latitude:

Why Does the Solstice Date Shift?

Earth's orbital period is approximately 365.2422 days, not exactly 365. Our calendar uses 365 days most years and 366 in leap years. This mismatch causes the solstice to drift by about 6 hours each year, then jump back nearly a full day in leap years. This is why the June solstice falls on June 20 in some years and June 21 in others.

The Leap Year Pattern

• Leap year: Solstice tends to be earlier (often June 20)
• Year after leap year: Solstice drifts later
• Two years after: Drifts later still
• Three years after: Latest timing, then reset by next leap year

How to Use This Tool

1. Enter a year: Type any year from 2000 to 2099.
2. Select your hemisphere: Choose Northern or Southern. The summer solstice occurs in June for the north and December for the south.
3. View results: See the exact solstice date and time, a live countdown, daylight estimate, corresponding winter solstice date, nearby years table, and decade timeline chart.

Summer Solstice vs Winter Solstice

• The summer solstice is the longest day of the year — most hours of sunlight.
• The winter solstice is the shortest day — fewest hours of sunlight.
• They are exactly 6 months apart. When one hemisphere has its summer solstice, the other has its winter solstice.

Cultural Significance

The summer solstice has been celebrated for thousands of years across cultures worldwide:

• Stonehenge (England) — the ancient monument is aligned with the sunrise on the summer solstice.
• Midsummer (Scandinavia) — one of the most important holidays, with bonfires, dancing, and flower wreaths.
• Inti Raymi (Peru) — the Inca Festival of the Sun, celebrated at the June solstice (winter solstice for the Southern Hemisphere).
• Litha — the pagan midsummer festival, one of the eight sabbats of the Wheel of the Year.

Frequently Asked Questions

What is the summer solstice?

The summer solstice is the moment when the Sun reaches its highest position in the sky for the year. In the Northern Hemisphere it occurs around June 20-21, marking the longest day and the start of astronomical summer. In the Southern Hemisphere, summer solstice falls around December 21-22.

What causes the summer solstice?

The summer solstice is caused by Earth's axial tilt of approximately 23.44 degrees. As Earth orbits the Sun, one hemisphere is tilted more directly toward the Sun at certain times of year. At the June solstice, the North Pole is tilted most directly toward the Sun, and at the December solstice, the South Pole is tilted most directly toward the Sun.

Is the summer solstice always on June 21?

No. In the Northern Hemisphere, the summer solstice can fall on June 20, 21, or rarely June 22, depending on the year. The exact moment varies because Earth's orbital period is not exactly 365 days. Leap years shift the timing slightly earlier, and then it drifts later over the next three years.

How long is the longest day of the year?

The longest day varies by latitude. At 40°N (e.g., New York, Madrid, Beijing), the summer solstice day is about 15 hours of daylight. At 50°N (London, Paris), it is about 16.5 hours. At the Arctic Circle (66.5°N), the Sun does not set at all, creating 24 hours of continuous daylight.

What is the difference between summer solstice and winter solstice?

The summer solstice is the longest day of the year (most daylight hours) and marks the start of astronomical summer. The winter solstice is the shortest day (fewest daylight hours) and marks the start of astronomical winter. They occur about 6 months apart. When it is summer solstice in one hemisphere, it is winter solstice in the other.

Additional Resources

• Summer Solstice - Wikipedia
• Axial Tilt - Wikipedia