The astronomical seasons for the Northern Hemisphere are best approximated as: An equinox occurs when the sun crosses the equator’s path and is positioned exactly between the Northern and Southern Hemispheres. The summer solstice also marks the first day of summer in astronomical terms for those living in the Northern Hemisphere.Īstronomers use the dates of the two solstices and two equinoxes to mark the seasons. The first day of summer – in astronomical terms This tilt is also what causes the changing seasons.įor several days or weeks before and after June 21, those living in the Arctic, including parts of Alaska, Canada, Greenland and Scandinavia, will have continuous daylight resulting in what is known as the midnight sun. This happens once every year because the Earth’s axis is tilted by about 23.5 degrees relative to its orbital plane around the Sun. The summer solstice occurs when the sun is at its highest position in the sky. Why is June 21 the longest day of the year? On that day, nearly 90 percent of the world’s population, who live above the equator in the Northern Hemisphere, will have the longest period of daylight in the year and also the shortest night.
It nearly always falls on June 21, but can also fall on June 20 or June 22 depending on the year and time zone you are in. December solstice to March equinox: 89.The summer solstice is an astronomical event that marks the longest day of the year and the start of summer in the Northern Hemisphere.September equinox to December solstice: 89.8 days.June solstice to September equinox: 93.6 days.March equinox to June solstice: 92.8 days.On average, summer lasts for 93.6 days in the Northern Hemisphere and 89.0 days in the Southern Hemisphere. The Earth does not move at a constant speed in its elliptical orbit, so the seasons are not of equal length. June | July | August | September Southern summer monthsĭecember | January | February | March How Long Is Summer? Read more about the history and meaning of the summer months: Northern summer months South of the equator, it starts in December and ends in March. In the Northern Hemisphere, astronomical and meteorological summer runs from June to September. Summer festivals: Midsummer, Epona, and a celebration of femininity Summer Months The start of summer and the summer solstice are celebrated in cultures and religions around the world with various traditions, holidays, and festivals. This is because it takes time for Earth to cool down, an effect known as seasonal lag.
© Shorter Days, but Rising TemperaturesĪlthough daylight hours decrease during the summer months, temperatures continue to rise in most regions. Places within the polar circles experience Midnight Sun or polar day during all or part of the summer season when the Sun does not set at all.Įarliest sunrise is not on the longest dayĮarth's position in relation to the Sun's rays at the June solstice. In Toronto, the longest day is just over 15 hours and 26 minutes long in Miami, roughly 2000 kilometers or 1200 miles farther south, it lasts about 13 hours and 45 minutes. Locations closer to the poles experience larger differences in day length throughout the year, so summer days are longer there. This means days get shorter during summer-very slowly at first, but at ever-larger daily intervals as the September equinox approaches, heralding the start of fall. Meteorological and other seasons definitions Days Get Shorter During SummerĪstronomical summer begins at the summer solstice, which is the longest day of the year. And, in some countries, the beginning of the seasons is determined by average temperatures rather than fixed dates or astronomical events.
Meteorologists use a different method of defining the first day of summer.
Business Date to Date (exclude holidays).
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