First Day Of Summer 20254 2025 Summer. Known in icelandic as 'sumardagurinn fyrsti', the first thursday after april 18th is an icelandic public holiday that. (in the southern hemisphere, it is around december 21 or 22.) this date is considered to be the first day of summer.

Read about first day of summer around the world in 2025. How many days left until summer 2025?