Autumn 2024. When is the first day of calendar and astronomical autumn?

Astronomical autumn begins at the autumnal equinox. In the northern hemisphere, it occurs between September 21 and 24, when the Sun passes through the point of Libra. The Earth passes the point in its orbit where the sun's rays fall perpendicularly on the equator and are simultaneously tangential to its surface at the poles. This year, this moment fell on September 22 at 2:43 p.m.

From then on, the northern hemisphere will be less illuminated than the southern one until the spring equinox. The astronomical autumn will last until the winter solstice, or December 21 or 22.

Calendar seasons always start on the same day. The first day of calendar autumn falls on September 23. This year we will welcome it one day later than the calendar autumn. It will last until December 21, when the calendar winter begins.

Astronomical and calendar seasons are not the only types of seasons. Meteorological autumn began on September 1. This concept was introduced for the needs of meteorologists and climatologists. It serves to always refer to the same period when comparing statistical or climate data.

Thermal autumn is also designated, a period characterized by an average daily air temperature of 5-15 degrees Celsius. The same is true for thermal spring.

In addition, we also distinguish phenological seasons. They are related to the development cycle of nature. These include the flowering and maturation of plants, the change of leaf colors or the behavior of animals. The period called early autumn is characterized primarily by flowering heather and the ripening of the horse chestnut or lingonberry. During autumn, the leaves change colour and fall off. At the turn of summer and autumn, some animals, such as storks, begin their journey from Poland to warm countries.