When Is The First Official Day Of Summer 2024. Summer 2024 starts on thursday, june 20th 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. Thursday, june 20 is the official first day of northern astronomical summer for 2024 โ summer solstice โ which is the longest day of the year for this half of the planet.
In the northern hemisphere, it typically. When is the first day of summer 2024.