What Is The Longest Day Of The Year 2024 Usa. It occurs when one of earth's poles is tilted toward the sun at its most. Some people call it the longest day, but to be precise, it's the day with the most daylight, because every day has 24 hours.

Here’s when the holiday falls in 2024 and why its celebrated. 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.