When Is The Longest Day Of 2024. Today (june 20) the summer solstice — the longest day of the year in the northern hemisphere — will begin, and it will be the earliest solstice in 228 years. This year's solstice is to fall on thursday, june 20, a day earlier than 2023.

The longest day in australia is 24 hours long i.e. Thursday, june 20 is the official first day of northern astronomical summer for 2024 — summer solstice — which is the longest day of the year for this half of the planet.