Here comes the Sun! Yes, the position of the Sun tells us when the four seasons begin.
Celebrate the First Days of Spring, Summer, Fall, and Winter
Each season has both an astronomical start and a meteorological start. It sounds complicated, but trust us, it’s not!
The astronomical start date is based on the position of the Sun in relation to the Earth.
The meteorological start date is based on our 12-month civiil calendar as well as the annual temperature cycle.
The First Days of the Seasons
Seasons of 2022 Astronomical Start Meteorological Start
SPRING Sunday, March 20, 11:33 A.M. EDT Tuesday, March 1
SUMMER Tuesday, June 21, 5:14 A.M. EDT Wednesday, June 1
FALL Thursday, September 22, 9:04 P.M. EDT Thursday, September 1
WINTER Wednesday, December 21, 4:48 P.M. EST Thursday, December 1
Note: The dates above correspond to the start of the listed seasons in the Northern Hemisphere. Times are based on Eastern time (ET). Subtract 3 hours for Pacific time, 2 hours for Mountain time, 1 hour for Central time, and so on.
The Definition of a “Season”
Here is more explanation about how astronomers and meteorologists define seasons differently:
The astronomical start of a season is based on the position of the Earth in relation to the Sun. More specifically, the start of each season is marked by either a solstice (for winter and summer) or an equinox (for spring and autumn). A solstice is when the Sun reaches the most southerly or northerly point in the sky, while an equinox is when the Sun passes over Earth’s equator. Because of leap years, the dates of the equinoxes and solstices can shift by a day or two over time, causing the start dates of the seasons to shift, too.
In contrast, the meteorological start of a season is based on the annual temperature cycle and the 12-month calendar. According to this definition, each season begins on the first of a particular month and lasts for three months: Spring begins on March 1, summer on June 1, autumn on September 1, and winter on December 1. Climate scientists and meteorologists created this definition to make it easier to keep records of the weather, since the start of each meteorological season doesn’t change from year to year.
The Old Farmer’s Almanac is an astronomical “calendar of the heavens,” so our book has long followed the astronomical definition of the seasons based on the Sun and Earth!
Temperate regions of Earth experience four seasons because of shifting sunlight, which is determined by how the Earth orbits the Sun and the tilt of our planet’s axis. As the Earth progresses through its orbit during the year, the tilt causes different parts of the Earth to be exposed to more or less sunlight, depending on whether we are tilted towards or away from the Sun.
Why Has Date Changed for Start of Seasons?
You may have noticed that the first day of spring used to be a different date when you were younger than it is today. The dates actually shift over time. Why?
There are several astronomical reasons but the one that’s easy to understand is: The Sun doesn’t follow a human calendar!
While our Gregorian calendar was designed to match the time it takes for the Earth to complete one orbit around the Sun, it’s not exact. Specifically, it eliminates leap days in century years not evenly divisible by 400, such 1700, 1800, and 2100, and millennium years that are divisible by 4,000, such as 8000 and 12000.
Therefore, the dates of the equinoxes and solstices can shift by a day or two over time, which causes the start dates of the seasons to shift over time, too.
Why Are The Seasons Different Lengths?
It can sometimes feel like winter is dragging on forever, but did you know that its actually the shortest season of the year? (In the Northern Hemisphere, that is.)
Thanks to the elliptical shape of Earth’s orbit around the Sun, Earth doesn’t stay the same distance from the Sun year-round. In January, we reach the point in our orbit nearest to the Sun (called perihelion), and in July, we reach the farthest point (aphelion). Read more about perihelion and aphelion.
When Earth is closer to the Sun, the star’s gravitational pull is slightly stronger, causing our planet to travel just a bit faster in its orbit. For those of us in the Northern Hemisphere, this results in a shorter fall and winter, since we are moving faster through space during that time of the year. Conversely, when Earth is farthest from the Sun, it travels more slowly, resulting in a longer spring and summer. (The opposite is true in the Southern Hemisphere.)
In other words, it takes Earth less time to go from the autumnal equinox to the vernal equinox than it does to go from the vernal equinox to the autumnal equinox.
Due to all this, the seasons range in length from about 89 days to about 94 days.
The Four Seasons
What defines each season? Below is a brief explanation of the four seasons in order of calendar year. For more information, link to the referenced equinoxes and solstices pages.
Spring
On the vernal equinox, day and night are each approximately 12 hours long (with the actual time of equal day and night, in the Northern Hemisphere, occurring a few days before the vernal equinox). The Sun crosses the celestial equator going northward; it rises exactly due east and sets exactly due west. See our First Day of Spring page.
Crocus field spring
Summer
On the summer solstice, we enjoy the most daylight of the calendar year. The Sun reaches its most northern point in the sky (in the Northern Hemisphere) at local noon. After this date, the days start getting “shorter,” i.e., the length of daylight starts to decrease. See our First Day of Summer page.
Autumn (Fall)
On the autumnal equinox, day and night are each about 12 hours long (with the actual time of equal day and night, in the Northern Hemisphere, occurring a few days after the autumnal equinox). The Sun crosses the celestial equator going southward; it rises exactly due east and sets exactly due west. See our First Day of Fall page.
Winter
The winter solstice is the “shortest day” of the year, meaning the least amount of sunlight. The Sun reaches its most southern point in the sky (in the Northern Hemisphere) at local noon. After this date, the days start getting “longer,” i.e., the amount of daylight begins to increase. See our First Day of Winter page.
A season is a period of the year that is distinguished by special climate conditions. The four seasons—spring, summer, fall, and winter—follow one another regularly. Each has its own light, temperature, and weather patterns that repeat yearly.
In the Northern Hemisphere, winter generally begins on December 21 or 22. This is the winter solstice, the day of the year with the shortest period of daylight. Summer begins on June 20 or 21, the summer solstice, which has the most daylight of any day in the year. Spring and fall, or autumn, begin on equinoxes, days that have equal amounts of daylight and darkness. The vernal, or spring, equinox falls on March 20 or 21, and the autumnal equinox is on September 22 or 23.
The seasons in the Northern Hemisphere are the opposite of those in the Southern Hemisphere. This means that in Argentina and Australia, winter begins in June. The winter solstice in the Southern Hemisphere is June 20 or 21, while the summer solstice, the longest day of the year, is December 21 or 22.
Seasons occur because Earth is tilted on its axis relative to the orbital plane, the invisible, flat disc where most objects in the solar system orbit the sun. Earth’s axis is an invisible line that runs through its center, from pole to pole. Earth rotates around its axis.
In June, when the Northern Hemisphere is tilted toward the sun, the sun’s rays hit it for a greater part of the day than in winter. This means it gets more hours of daylight. In December, when the Northern Hemisphere is tilted away from the sun, with fewer hours of daylight.
Seasons have an enormous influence on vegetation and plant growth. Winter typically has cold weather, little daylight, and limited plant growth. In spring, plants sprout, tree leaves unfurl, and flowers blossom. Summer is the warmest time of the year and has the most daylight, so plants grow quickly. In autumn, temperatures drop, and many trees lose their leaves.
The four-season year is typical only in the mid-latitudes. The mid-latitudes are places that are neither near the poles nor near the Equator. The farther north you go, the bigger the differences in the seasons. Helsinki, Finland, sees 18.5 hours of daylight in the middle of June. In mid-December, however, it is light for less than 6 hours. Athens, Greece, in southern Europe, has a smaller variation. It has 14.5 hours of daylight in June and 9.5 hours in December.
Places near the Equator experience little seasonal variation. They have about the same amount of daylight and darkness throughout the year. These places remain warm year-round. Near the Equator, regions typically have alternating rainy and dry seasons.
Polar regions experience seasonal variation, although they are generally colder than other places on Earth. Near the poles, the amount of daylight changes dramatically between summer and winter. In Barrow, Alaska, the northernmost city in the U.S., it stays light all day long between mid-May and early August. The city is in total darkness between mid-November and January.
What’s your favorite season—and why? Let us know in the comments below!
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