When does summer start?
Usually, when we talk about the first day of summer, we are referring to the astronomical summer which is defined by the Earth's axis and orbit around the Sun.
The astronomical calendar determines the seasons due to the 23.5 degrees of tilt of the Earth's rotational axis in relation to its orbit around the Sun. Both Equinoxes and Solstices are related to the Earth's orbit around the Sun.
This year, astronomical summer began on 21 June 2021 and ends on 22 September 2021.
For upcoming years, the dates for astronomical summer will be;
|Year||Summer Starts||Summer Ends|
|Tuesday, 21 June 2022||
Friday, 23 September 2022
|Wednesday, 21 June 2023||
Saturday, 23 September 2023
|Thursday, 20 June 2024||
Sunday, 22 September 2024
However, meteorologists are also interested in the beginning of the meteorological summer. Meteorological summer will always begin on 1 June; ending on 31 August.
The meteorological seasons consist of splitting the seasons into four periods made up of three months each. These seasons are split to coincide with our Gregorian calendar, making it easier for meteorological observing and forecasting to compare seasonal and monthly statistics.
Solstices and equinoxes
Solstices and equinoxes are the astronomical transition points between the seasons and mark key stages in the astronomical cycle of the Earth. In a year there are two equinoxes (spring and autumn) and two solstices (summer and winter). The dates of the Equinoxes and Solstices aren't fixed due to the Earth's elliptical orbit of the Sun. The Earth's orbit around the Sun means that in early January, the Sun is closest (known as perihelion) and in early July it is most distant (aphelion).