After the sun arrives at its solstice point, it will begin to migrate back toward the south and the amount of daylight in the Northern Hemisphere will begin to decrease.

Seasonal or Environmental Lag is what meteorologists use to describe the delay between peak solar heating - on the summer solstice - and the hottest average temperatures of the year, which are about a month later.

The 2025 summer solstice falls on Friday, June 20, at 10:42 p.m. ET, according to NASA and the Old Farmer's Almanac. This marks the longest day of the year in the northern hemisphere, when the Earth's tilt positions it closest to the Sun.