September 2026 is on course to become the warmest September ever recorded in Spain, according to the latest assessment from the State Meteorological Agency.

With observations through September 22 and forecasts for the final days of the month, AEMET estimates that September's average temperature will reach 22.4°C.

That would make it the warmest September in the agency's historical series, which begins in 1961.

A September warmer than the average Spanish summer

The projected 22.4°C average would be 3.3°C above the normal temperature for September.

It would also be higher than the average temperature recorded across the Spanish summer season, which stands at 22.1°C.

AEMET described the unusual situation by saying September 2026 could effectively be considered “another month of summer”.

The forecast would put this September more than 0.5°C above the previous September records, set in 1987 and 1964.

The heat has continued into autumn

The arrival of astronomical autumn has done little to change the overall picture.

On the day autumn began, temperatures close to 40°C were recorded in parts of the Guadiana and Guadalquivir valleys, while more than 100 AEMET weather stations exceeded 35°C.

AEMET expects temperatures to fall during the final days of September, but its current assessment indicates that the decline will not be enough to prevent the month from finishing at the top of the historical September rankings.

Ibiza and the Balearics have also experienced exceptional heat

The unusual September comes after an exceptionally warm summer across the Balearic Islands.

AEMET's assessment of June, July and August classifies the summer in the Balearics as extremely warm. Across Spain, the summer of 2026 was the warmest in the official series, with the peninsula recording an average temperature of 24.5°C, 2.4°C above the 1991-2020 reference average.

The agency has also recorded an unusually persistent run of hot weather during 2026. A total of 61 days under heatwave conditions were recorded across the Peninsula and Balearic Islands during the year, a record for the period covered by AEMET's current heatwave series.

For the Balearics, AEMET's seasonal outlook for September, October and November places temperatures in the upper tercile with high probability.

A longer summer in 2026

AEMET says the conditions of full summer extended beyond the traditional June-to-August season this year.

Very high temperatures were already recorded during the second half of May and continued into September, effectively extending summer-like conditions over four months.

The agency's analysis also found that the summer of 2026 was the warmest in Spain since at least 1869 when its reconstructed historical climate series is taken into account.

What happens next?

The final days of September are expected to bring some relief from the exceptional heat, but AEMET's broader outlook continues to point towards warmer-than-normal conditions.

The agency currently gives a 60-70% probability that the autumn season will be warmer than normal across Spain, compared with a 10% probability of a colder-than-normal autumn.

For Ibiza and the rest of the Balearics, the seasonal forecast also points towards above-normal temperatures during September, October and November.

The final September ranking will only be known once the month has ended and the complete observations have been analysed.

For now, however, the figures point to an extraordinary continuation of summer-like weather across Spain, with Ibiza and the Balearics experiencing the same broader pattern of unusually persistent warmth.