Summer Solstice 2025: Date, time and meaning of longest day of the year

20 June 2025, 15:28

By Alice Dear

When is the longest day of the year 2025? Does the longest day of the year change? How many hours of sunlight will we get in the UK during the Summer Solstice?

The longest day of the year for 2025 will occur on Saturday, June 21 at exactly 3:42am, when the sun is at its highest position in the sky, marking the Summer Solstice and the start of the astronomical summer.

While the Summer Solstice is actually a specific time of the day, people generally celebrate the day as it marks the day where we experience the most amount of hours of sunlight.

It occurs due to the fact that the Earth's rotation axis is tilted slightly at 23.44°, this creates seasons and means that one half of the year the North side of the planet is tilted slightly towards the Sun and the South is tilted away.

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The longest day of the year is when the tilt of the Earth is the closest to the sun, meaning more hours of exposure to sunlight.

When is the longest day of the year 2025?

The longest day of the year for 2025 will occur on Saturday, June 21 at exactly 3:42am, when the sun is at its highest position in the sky, marking the Summer Solstice and the start of the astronomical summer.

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Why is it the longest day of the year?

The longest day of the year, also known at the Summer Solstice or Midsummer, marks the day when there is the most hours of sunlight and the least hours of darkness.

The summer solstice, while believed by many to be a day, is actually a specific time of the longest day of the year when the hemisphere you're in is most tilted towards the sun. For us in the UK, this will occur at 3:42am.

Does the longest day of the year change?

The longest day of the year or the Summer Solstice has changed dates over the years, but have only differed from two dates; 20th and 21st June.

This is because, as explained by Space.com: "The solstices also do not land on the same calendar day every year because the astronomical year is 365.25 days long."

When is sunrise and sunset on longest day of the year?

The sunrise will occur at 4:44am on the longest day of the year in 2025, and the sunset is set to happen at 9:21pm in the evening.

This means that on June 21, we will enjoy 16 hours and 37 minutes of sunlight.