Spain heads into astronomical autumn with midsummer heat

Astronomical autumn begins on Wednesday – but instead of cooler air, large parts of Spain can expect sunshine and temperatures above 30°C. In the southwest, highs could even reach 37°C.

Astronomical autumn begins in the Northern Hemisphere on Wednesday, 23 September 2026, at 02:05. In Spain, however, there will initially be little sign of the changing season. Instead of jacket weather, sunshine, dry conditions and widespread midsummer temperatures are on the cards.

The 02:05 time applies to mainland Spain and the Balearic Islands. In the Canary Islands, the equinox occurs at 01:05 local time.

Up to 37°C as autumn begins

Our latest ICON-EU forecast from 19 September, 00 UTC, shows exceptionally warm temperatures for Wednesday. Across large parts of inland Spain, daytime highs are forecast to climb well above 30°C.

The hottest conditions are expected in the west and southwest. Badajoz and Seville could reach around 37°C, while Plasencia and Córdoba are forecast to reach about 36°C. Toledo could see 35°C, with Madrid and Ciudad Real around 34°C, making for an exceptionally hot first day of astronomical autumn.

It will remain unusually warm farther north as well. Zamora and Lleida could reach around 33°C, León, Zaragoza and Murcia around 31°C, and Pamplona about 30°C.

This continues the late-summer warmth already expected in the preceding days. Our previous ICON-EU forecast also indicated a significant rise in temperatures, with widespread highs above 30°C and peaks of 35–36°C in Spain's hottest regions.

More comfortable on the coasts

Holidaymakers spending their time by the sea can also expect plenty of sunshine, but in most coastal areas they should avoid the extreme heat forecast for the interior.

On the Costa del Sol, Málaga is expected to reach around 27°C, while the Costa de Almería should see about 26°C. Benidorm is forecast to reach 29°C, Valencia also around 29°C, and Barcelona approximately 26°C.

Conditions will be similar across the Balearic Islands, with Palma around 27°C and Eivissa about 28°C. In many popular holiday destinations, it will therefore still feel much more like beach weather than autumn.

Only Spain's northern coast will be noticeably fresher. Gijón is forecast to reach around 21°C, A Coruña 23°C and Bilbao about 25°C.

Plenty of sunshine and little rain

It is not only the temperatures that will feel like summer. Skies are expected to remain mostly clear across large parts of Spain, while significant areas of rainfall are barely a feature in the current forecast.

Astronomical autumn will therefore begin across much of Spain with conditions more reminiscent of July or August: plenty of sunshine, dry weather and, in inland areas, potentially intense heat.

The calendar says autumn – but the weather is still unmistakably summer.

What does the start of astronomical autumn mean?

Astronomical autumn begins with the September equinox. At this point, the location where the Sun is directly overhead crosses the equator towards the Southern Hemisphere. In 2026, this occurs on 23 September at 00:05 UTC, or 02:05 CEST.

When does autumn begin? Two calendars compared

Seasons in 2026, meteorological and astronomical

Astronomical Meteorological

Wed 23 Sep: up to 37°C

Meteorological

Winter Spring Summer Autumn

Astronomical

Winter Spring Summer Autumn

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Astronomical autumn: from 23 September at 02:05 until the winter solstice on 21 December. It follows the position of the Sun: at the equinox, the Sun stands directly overhead at the equator at midday.

However, this astronomical date does not mean that the weather suddenly changes. Even after the equinox, Spain can still experience pronounced late-summer or even midsummer-like weather patterns.

And that is exactly what appears to be happening this year: autumn begins, but Spain is holding on to summer for now.

The temperature figures are based on the ICON-EU model run from 19 September 2026, 00 UTC. As the forecast is still several days ahead, some changes are possible before Wednesday.