First Day Summer 2026. In the northern hemisphere, it always occurs around june 20 or 21. Monthly day distribution the following table displays the number of days in each month for both 2025 and 2026.

Note that the number of days in each month remains. Summer 2026 starts on sunday, june 21st in the northern hemisphere, with the first day of summer being the longest daylight day of the year with the earth’s axis having reached its furthest tilt and begins to change directiion back.