Summer Solstice 2024 Usain. By the time we reach the summer solstice on june 20, 2025, it will be the longest day of the year. This means the longest day of the year and then the slow decrease of day length through the fall equinox.

The summer solstice occurs when the earth’s axial tilt is approximately 23.5 degrees relative to its orbit around the sun. Thursday, june 20 is the official first day of northern astronomical summer for 2024 — summer solstice — which is the longest day of the year for this half of the planet.