Spain is expecting its first heatwave of the summer as the arrival of a mass of hot air from Africa could send temperatures above 40C over the weekend.

The scorching temperatures, which are more usual in late-July or early-August, are arriving earlier than usual in the year and will be exacerbated by a lack of wind in certain parts of the peninsula. High levels of humidity will cause so-called ‘tropical nights’ in many parts of the country where the mercury will not fall below 20C overnight.

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In some southern cities, such as Seville and Cádiz, overnight temperatures could be a sweltering 25C.

Temperatures on Thursday will top 30C across many parts of the country, but the highest will be in the southeast of the country, particularly in the Guadalquivir valley area and inland Murcia where temperatures will hit 35C.

On Friday, the mercury will continue to rise and the highs could be close to reaching 40C across the south, and over the weekend temperature could yet climb higher. There will be temperatures around 30C in the north, and 35C in inland Spain.

AEMET forecast graphics, seen below, show how the heatwave will be particularly clustered in the southwest of the country.

#Predicción de #temperaturas máximas y mínimas para #hoy y sus variaciones (2/2). https://t.co/nkt7p7WaxU pic.twitter.com/F6ATCGJx9D

— AEMET (@AEMET_Esp) June 22, 2023

On Saturday and Sunday, the most intense heat is expected in the southwest of the peninsula, especially in the Guadalquivir valley. On Saturday, Córdoba and Seville could reach 41C and on Sunday 42C and 43C respectively.

Other cities in the southwest, such as Badajoz, also seem set to exceed 40C over the weekend, and similarly scorching temperatures are forecast across many areas of Andalusia, in the west of Castilla-La Mancha, as well as in the Madrid region.

Temperatures will surpass 35C in much of inland Spain, and be above 30C in the northern half of the country with 30C expected in Bilbao on Saturday.

The heat will be more bearable in the Canary Islands, where maximums temperatures are not expected to reach 30C. The Balearics are forecast to see temperatures in the low-30s throughout the weekend.

Forecasts from Spain’s state meteorological agency AEMET predict that the heatwave is here to stay and will last until at least the first days of next week, possibly longer. On Monday, the 26th, temperatures of 43C could be seen again in the southwest of the country.

By Tuesday and Wednesday, AEMET forecasts that temperatures will have dropped to a more comfortable 22 or 23C in northern Spain, but the high temperatures will remain in southern Spain. On Wednesday, Cordoba is set for highs of 44C, and temperatures will hover in the high-30s and low-40s across Andalusia.

The heatwave follows weeks of turbulent weather in Spain, with flash flooding and wildfires across differing parts of the country, as well as record temperatures in April.

Officially speaking, for scorching weather to be classified as a heatwave, the period of extreme heat must last at least three days and temperatures must exceed seasonal thresholds by 10 percent.