World Longest Day 2025 Time. This is the day when the sun's annual journey through the constellations of the zodiac carries it to its. In 2025 the summer solstice will occur on saturday 21 june at 03.42 bst (02.42 gmt).

The longest day in australia is 24 hours long i.e. 20 june will be the longest day of 2025 in the northern hemisphere, midsummer day.