This is when Aemet forecasts the arrival of an Indian summer in Spain with mercury climbing back up to 30C

The autumn season has already begun to make its mark in Spain, where heavy rainfall coupled with a sharp drop in temperatures in some areas has complicated the weather in the last few hours. The new season has settled in over the Spanish mainland with temperatures between 5 and 10C below normal, and much instability in the atmosphere.

This situation will remain the same for a few more hours, with provinces registering minimum values below five degrees and temperatures far from 30ºC in most of the country. However, the situation will take a radical change in the coming hours to say goodbye to the autumnal cold. This has been announced by Spain's state meteorological agency (Aemet), which has already set a date for the return of weather stability in the country.

It is expected that, in the next few hours, we will see the arrival in Spain of what is popularly known as "veranillo de San Miguel" (Indian summer), a common phenomenon in the last days of September. Therefore, from Thursday, this 'veroño' will bid farewell for several days to the cold to give way to much more stable, warmer and drier weather, bringing back the feel of the summer months to many areas of the Spanish mainland.

The passage of a trough over Spain, accompanied by a mass of cold air at high altitude, has marked the last few days in the country. The cold has already settled in many regions of Spain, where the maximum temperatures in recent days have been below 20C. In fact, in some parts of the mainland, maximum temperatures have been up to 10C lower than usual for the season.

Today (Wednesday) will be the coldest day of the week, with values almost typical of autumn in some areas of the interior of the peninsula. In some provincial capitals, such as Burgos, Ávila, Palencia or Segovia, as well as in parts of Cantabria or the Basque Country, the minimum temperatures will drop to below 5C.

This drop in temperatures will also be quite noticeable in the centre of the mainland, where the lowest values will be around 10C. Meanwhile, in Andalucía and Murcia, as well as in other Mediterranean areas, maximum temperatures will be close to 20-25C, while minimum temperatures will not drop below 15 degrees.

It will be quite dry over most of the mainland, although instability will continue in other areas of the country. Both today and Thursday, showers will be recorded in the Mediterranean, eastern Cantabrian and Pyrenees regions. In addition, the heaviest accumulations of rain will be seen in the Basque Country and Catalonia, where some heavy storms could arrive.

The below-average temperatures of this week will not last for long. As usual at this time of year, over the next few days Spain will experience what is now popularly known as the "Veranillo de San Miguel", according to the Aemet in its latest forecast. This period, which usually coincides annually with Saint Michael's Day (29 September), is usually marked by exceptionally dry and warm weather.

Although it may not happen at all or it may be delayed, everything points to the fact that this year it will take place days before the celebration of this festivity. This has been announced by the meteorological agency, which anticipates that the cool atmosphere of the last few days will give way to much higher temperatures on Thursday, 25 September.

It will be from this day onwards when a mass of warm air begins to gain ground on the cold of the last few days, bringing the popular San Miguel summer. This situation will leave a "warm and stable atmosphere" in Spain, allowing temperatures to rise even well into the weekend.

As a result, from this Thursday until next Sunday, temperatures in almost all Spanish regions could rise by between 5 and 10C compared to the beginning of the week. In some areas of the south and centre of the mainland, temperatures could return to 30C, while in the Guadalquivir valley they will likely climb above 32C.