The June solstice – your signal to celebrate summer in the Northern Hemisphere and winter in the Southern Hemisphere – occurs on June 21, 2019, at 15:54 UTC. For us in the Northern Hemisphere, this solstice marks the longest day of the year. Early dawns. Long days. Late sunsets. Short nights. The Sun at its height each day, as it crosses the sky. Meanwhile, south of the equator, winter begins.