Summer Solstice 21 June 2025: What it means and how it changes our day

Summer Solstice 2025 Date: When Is the Longest Day of the Year? (Image: Canva)

For early risers and sun seekers, it’s a date. The summer solstice returns on Saturday, 21 June, bringing the longest day of the year.

As sunshine spills across the Northern Hemisphere, this day marks more than just warmth—it’s the astronomical start of summer, even though meteorologically we’ve already been in it since 1 June.

The Science Behind the Solstice

The Earth revolves around the Sun on a slanted axis. This is what causes variations in seasons and daylight hours. During the solstice, the Northern Hemisphere slants most toward the Sun, which then positions itself directly over the Tropic of Cancer.

This tilt of the planet provides us with our longest period of daylight. But it's not the earliest sunrise or the latest sunset. Those come earlier and later than the solstice because of the Earth's orbit being complicated.

In regions near the Arctic Circle—such as Norway and Alaska—the Sun doesn't go down. That period of continuous daylight is referred to as the midnight sun, and it lasts for days near the solstice.

A Toasty Welcome to Summer

This year's solstice might come with some serious warmth. Temperatures are predicted to reach close to 33°C in certain UK areas. Nevertheless, the solstice heat record is still intact—Heathrow Airport reached 34.5°C in 2017.

Curiously, the warmest UK weather tends to arrive weeks following the solstice. That is because the ground and air take time to fully heat up, gathering heat over days of prolonged sunshine.

Why the Solstice Date Varies

The date of the solstice varies slightly from one year to another, normally between 20 and 22 June. This variation occurs because Earth's orbit isn't perfectly aligned with our calendar.

It takes approximately a quarter-day longer than 365 days to make a complete circuit around the Sun. That's why we insert a leap day every four years—to keep in step.

The term "solstice" is derived from Latin, where "sol" (Sun) and "sistere" (to stand still) were combined, suggesting the Sun's seeming halt at its peak position in the sky.

Looking Up and Looking Ahead

Whether you're observing a sunrise or basking at the late sunset, solstice reminds us of our world's dance with the Sun.

It is a change not only in terms of seasons but of spirit—almost for everyone, it signals a sense of hope, vigor, and expectation of warm-weather days to come.