Seasons 2020: spring begins 20 March at 03:49 UTC
Astronomical spring in the northern hemisphere opens at the March equinox, Friday, 20 March 2020 at 03:49 UTC. Summer follows at the June solstice on 20 June 2020, autumn at the September equinox on 22 September 2020 and winter at the December solstice on 21 December 2020. South of the equator the same four instants open autumn, winter, spring and summer instead.
When does spring start in 2020?
Astronomically, at Friday, 20 March 2020 at 03:49 UTC, the moment the Sun crosses the celestial equator heading north. That is day 80 of 2020. Meteorologists use a different convention entirely, fixing spring to 1 March through 31 May so that seasonal statistics line up with whole calendar months. Neither definition is wrong; they answer different questions. All four turning points of 2020 have passed.
When is the longest day of 2020?
The June solstice, Saturday, 20 June 2020 at 21:43 UTC, when the Sun reaches its northernmost point. North of the equator that is the longest day and the shortest night of the year; south of it, the exact reverse. The December solstice on Monday, 21 December 2020 at 10:02 UTC mirrors it. Between the two, the Sun's noon height at any fixed latitude swings through the full range it will cover all year.
| Turning point | Date | Time (UTC) | Weekday | Day of year |
|---|---|---|---|---|
| March equinox | 20 March 2020 | 03:49 UTC | Friday | 80 |
| June solstice | 20 June 2020 | 21:43 UTC | Saturday | 173 |
| September equinox | 22 September 2020 | 13:30 UTC | Tuesday | 267 |
| December solstice | 21 December 2020 | 10:02 UTC | Monday | 356 |
How long is each season in 2020?
The four seasons are not equal. Measured between the turning points, the longest in 2020 is summer at 93.66 days and the shortest is winter at 88.98 days, a difference of 4.68 days. The cause is the Earth's elliptical orbit: it moves fastest when closest to the Sun in early January and slowest when furthest away in early July, so the arc between the September equinox and the March equinox is crossed more quickly than the other half.
| Northern season | Southern season | Begins | Time (UTC) | Weekday | Length in days |
|---|---|---|---|---|---|
| Spring | Autumn | 20 March 2020 | 03:49 UTC | Friday | 92.75 |
| Summer | Winter | 20 June 2020 | 21:43 UTC | Saturday | 93.66 |
| Autumn | Spring | 22 September 2020 | 13:30 UTC | Tuesday | 89.86 |
| Winter | Summer | 21 December 2020 | 10:02 UTC | Monday | 88.98 |
Why do the season dates move?
A tropical year, one March equinox to the next, is about 365.2422 days rather than a whole number. Each ordinary calendar year therefore ends roughly six hours before the Earth has finished its circuit, and the equinox drifts about six hours later on the clock. A leap day pulls it back by a whole day, which is why the date cycles across a three or four day window rather than creeping steadily. In 2020 the March equinox falls on the 20th and the December solstice on the 21st.
Clock changes in 2020
Daylight saving is statutory, not astronomical, and the rules differ. In the United States clocks go forward on 8 March 2020 and back on 1 November 2020, the second Sunday in March and the first Sunday in November. In the United Kingdom and across the European Union the change falls on 29 March 2020 and 25 October 2020, the last Sunday in March and the last Sunday in October. That leaves a gap of 21 days in spring when American and British clocks are an hour closer together than usual.
Questions
- When does spring start in 2020?
- Friday, 20 March 2020 at 03:49 UTC, at the March equinox.
- When is the summer solstice in 2020?
- Saturday, 20 June 2020 at 21:43 UTC.
- When is the winter solstice in 2020?
- Monday, 21 December 2020 at 10:02 UTC.
- Are the seasons the same length?
- No. In 2020 they run from 88.98 to 93.66 days because the Earth's orbit is elliptical.
Seasons in other years
More for 2020
Day of the year · Event countdowns · When is it? · Date calculator