2025 Summer Calendar Yearbook Ideas. Online calendar of holidays and days off in united states for the summer of 2025. 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.

Online calendar of holidays and days off in united states for the summer of 2025. International day for preventing the exploitation of the environment in war.