In 2022, the June solstice occurs on Tuesday, June 21, marking the start of summer in the Northern Hemisphere. Here’s everything you should know about the summer solstice—what it means, why it’s the longest day of the year, and how to celebrate. In the Northern Hemisphere, the June solstice (aka summer solstice) occurs when the Sun reaches its highest and northernmost points in the sky. It marks the start of summer in the northern half of the globe.