The first day of summer arrives on …. Here's the live count:
Counting down to something else — a vacation, say? Build your own with the countdown timer, or browse all holiday countdowns.
Astronomically, summer in the Northern Hemisphere begins at the June solstice, the moment the North Pole leans closest to the sun. That moment falls on June 20, 21, or 22 depending on the year, and this countdown uses June 20 as its target each year. The exact solstice moment varies slightly from year to year — it can slip a day either side of the 20th — so treat June 20 as the fixed marker this page counts to, and check the date shown above if you're planning around the precise day. Weather forecasters use a simpler convention: meteorological summer runs from June 1 to August 31, splitting the year into tidy three-month seasons.
Earth's axis is tilted about 23.5 degrees, and as the planet orbits, that tilt points each hemisphere toward or away from the sun in turn. On the June solstice the tilt toward the sun is at its maximum for the Northern Hemisphere: the sun reaches its highest and northernmost point in the sky, rises earliest, sets latest, and the day is the longest of the year. After the solstice the days begin, almost imperceptibly at first, to shorten again. How long the longest day lasts depends on latitude — around 14–15 hours of daylight across most of the United States, over 18 hours in Alaska, and a full 24 hours of daylight above the Arctic Circle. South of the equator, the same moment is the winter solstice and the shortest day of the year.
Of all the countdowns on this site, this is the one that tracks anticipation rather than a celebration: school holidays, warm evenings, swimming lakes and oceans, and trips booked months ahead. If the trip has its own date, the countdown builder can count to that instead.
Why isn't the solstice on the same date every year? A year isn't a whole number of days — it's about 365 days and 6 hours. Those extra hours push the solstice later each year until a leap day pulls it back, which is why it oscillates between June 20 and June 22.
If it's the longest day, is it also the hottest? Usually not. Land and oceans take weeks to warm up, so the hottest weather typically lags the solstice by a month or more — a delay called seasonal lag.