First Day Of Summer 2025 Canada Date. Summer 2025 starts on friday, 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. Spring equinox 20 march, summer solstice 20 june, autumn equinox 22 september, winter solstice 21 december.
Is the solstice the longest day of the year?โand more! When is the first day of summer 2025?