Spain is preparing to enter astronomical autumn, but the change of season will not immediately bring cooler weather.

AEMET forecasts a continuation of unusually warm conditions across much of the country during the final days of September, with temperatures remaining well above the normal values for the time of year.

The warm spell coincides with the dates traditionally associated with the “Veranillo de San Miguel”, although the expression itself is a popular weather term rather than a formally defined meteorological phenomenon.

What Is the Veranillo de San Miguel?

The Veranillo de San Miguel is a traditional Spanish expression used for a short period of warmer weather around the end of September, close to the September 29 feast day of Saint Michael.

It is also known as the Veranillo de los Arcángeles or Veranillo del Membrillo.

There is no requirement for the phenomenon to occur every year, and it does not have a precise meteorological definition. A warm spell appearing around this time can therefore be described using the traditional term, but it should not be treated as a specific atmospheric event with a guaranteed start or end date.

Spain Remains Much Warmer Than Normal

AEMET's latest weekly outlook shows that the week from September 21 to 27 will remain distinctly summer-like across Spain.

From Tuesday, September 22, maximum temperatures of 32°C to 34°C are expected across extensive areas of mainland Spain, with around 35°C possible in parts of southern Galicia, the Ebro depression, Extremadura and the Guadalquivir Valley.

The agency expects mostly clear or partly cloudy skies and generally limited rainfall.

AEMET said this pattern was likely to continue, with little significant change expected through at least Friday, September 25.

Up to 39°C Forecast in Badajoz

The most notable temperatures are expected in parts of the southwest.

The forecast cited in the supplied report indicates that Badajoz could reach up to 39°C on Wednesday, September 23, while Córdoba and Seville could approach 37°C.

Because AEMET's broader weekly outlook gives a lower regional range of around 35°C for Extremadura, the 39°C figure is best treated as a specific short-range forecast for Badajoz rather than a general temperature forecast for the whole region.

Autumn Arrives on September 23

Astronomical autumn begins on Wednesday, September 23.

The seasonal transition itself does not mean that temperatures will immediately fall, and AEMET expects the warm conditions to continue beyond the equinox.

The forecast therefore points to an autumn that initially feels much more like an extension of summer in many parts of Spain.

Baleares Also Remain Warm

The Balearic Islands are also expected to remain warm during the middle of the week.

For Ibiza, AEMET's current beach forecast for Ses Figueretes shows a maximum of around 30°C on Wednesday, September 23, with clear skies during the morning and afternoon, light winds and weak swell.

The forecast also puts the sea temperature at around 27°C on Wednesday.

For Thursday, September 24, the same Ibiza forecast gives a maximum of around 29°C, with some cloud during the morning followed by clearer conditions.

A Warm End to September

AEMET's outlook extends beyond the immediate four-day period and indicates that above-normal temperatures are likely to persist into the following weeks, although confidence decreases as the forecast period becomes longer.

For September 28 to October 4, the agency currently expects temperatures to remain above the usual levels for the time of year, particularly in northeastern Spain.

The longer-range forecast is more uncertain, and AEMET notes that future updates could change the outlook.

2026 Has Already Been Exceptionally Warm

The latest developments come after an unusually hot summer.

AEMET reported on September 21 that summer 2026 was the warmest summer in Spain's official record dating back to 1961, with a mean temperature in mainland Spain of 24.5°C, 2.4°C above the 1991-2020 reference average.

Using a reconstructed climate series going back to 1869, AEMET said 2026 was also the warmest summer in at least a century and a half.

The agency noted that summer-like conditions extended beyond the conventional June-August period, with particularly high temperatures also recorded during the second half of May and the first part of September.

Autumn Is Expected to Start Warm

AEMET's seasonal outlook also points towards a warmer-than-normal autumn.

For September, October and November, the agency gives a 60% to 70% probability that temperatures will be in the upper tercile across Spain, based on the 1991-2020 reference period.

The warm signal is particularly pronounced in northern and eastern mainland Spain, the Balearic Islands and the Canary Islands.

What the Weather Means for Ibiza

In Ibiza, the immediate outlook remains firmly summer-like.

Wednesday's forecast combines around 30°C, clear skies, light winds and weak sea conditions at Ses Figueretes, while the water temperature remains around 27°C.

That means the island's transition into autumn is expected to be gradual rather than abrupt, with conditions still suitable for beaches, swimming and outdoor activities during the final days of September.

Summer-Like Conditions Continue

The traditional “Veranillo de San Miguel” may be a popular description for the late-September warmth, but the official meteorological picture is more straightforward.

AEMET is forecasting a prolonged period of above-normal temperatures and generally limited rainfall across much of Spain, while Ibiza is also expected to remain warm as astronomical autumn begins.

For now, autumn may have arrived on the calendar, but the weather across much of Spain is still holding on to summer.