Summer is facing its last days and autumn already has a date of arrival in Spain. The new season will officially begin on Wednesday, September 23 at 02:05 hours, according to calculations from the National Astronomical Observatory, dependent on the National Geographic Institute (IGN).
It will be then when the autumn equinox occurs, the moment when the center of the Sun crosses the celestial equator in its apparent movement towards the south. The season will last approximately 89 days and 21 hours, until December 21, when winter will begin.
Although the astronomical autumn will not arrive until the end of September, the meteorological autumn began on September 1 and includes the months of September, October, and November.
Autumn arrives after a summer marked by heat
The arrival of the new season does not necessarily mean that temperatures will drop immediately. In fact, current forecasts point in the opposite direction.
The seasonal prediction from AEMET for September, October, and November indicates a probability of between 60% and 70% that temperatures will be above the usual values, especially in the north and east of the Peninsula, Balearic Islands, and Canary Islands. The possibility that the quarter will be colder than normal is around 10%.
This does not mean that it will be hot for three months continuously. Seasonal predictions show general trends for long periods and do not allow anticipating what each week or each weather episode will be like.
In fact, AEMET already points to a warmer September than usual. For the week of the 7th to the 13th, models indicate temperatures above the average in much of the country, while the warm trend also appears in the following weeks, although with greater uncertainty.
Rainfall, the great unknown of autumn
If temperatures show a relatively clear signal, the prediction of precipitation is much more uncertain.
AEMET warns that rainfall is especially difficult to anticipate on a seasonal scale, as a single episode of intense precipitation can significantly alter the balance of an entire quarter. Therefore, the agency asks to interpret these predictions as trends and not as a concrete forecast of storms or DANAS.
In some areas, there are indeed some signals. In September, the probability of precipitation above normal is greater in the Mediterranean slope, while in October and November that trend shifts towards the northwest of the peninsula. In the southwest, no clear trend is observed.
In the Canary Islands, for its part, the forecast points to an especially warm autumn with a higher probability of being drier than normal: AEMET places the possibility of a dry quarter at around 40% compared to 10% that it will be wetter.
When will autumn really start to be felt?
The change of season will be gradual. Although the equinox officially marks the beginning of astronomical autumn, temperatures may continue to be summer-like for a good part of September.
In fact, the current forecast from AEMET indicates that the heat could extend during the first weeks of the month, with values above normal in large areas of Spain. The thermal drop will arrive irregularly and will depend on the entry of cooler air masses and changes in atmospheric circulation.
Therefore, September 23 will not mean a sudden change in weather. Autumn will begin on the calendar, but the heat could still be the main character.
The time change will come in October
Autumn will also bring the traditional time change. In 2026, the current system will remain in effect, as its elimination has not been approved.
The change will take place on Sunday, October 25. At 03:00 in the morning, the clocks in mainland Spain will be set back one hour and will return to 02:00. In the Canary Islands, the change will occur at 02:00, when the clocks will move to 01:00.
Thus, autumn 2026 will officially begin on September 23, but everything points to summer taking a little longer to say goodbye. The AEMET forecast outlines a season with temperatures above normal and rainfall that is much more difficult to predict, in a context where Spain comes from a particularly warm period.