The peak of Indian summer arrives, but there is already a date for a clear refreshment

BarcelonaTemperatures rose more yesterday, with very warm weather for the time of year in the pre-coastal areas and inland. Temperatures already approached 30ºC in towns in Ponent and the Ebro region, but they did not quite reach it by a few tenths. Notable were the 29.7ºC maximums recorded in Alcarràs (Segrià) or in Vallfogona de Balaguer (Noguera). From today onwards, thermometers will peak and the first official 30 °C of this year can be reached in Ponent and inland Ebro. We are talking about values between 7 and 12 degrees above the usual average for this time of year inland and in the Pyrenees.

This advanced Indian summer is the result of a very warm air mass loaded with dust in suspension, driven from North Africa by the counter-clockwise rotation of a low-pressure system located between the southwestern Iberian Peninsula and the Canary Islands. The exception will be found on the coast, where, as has already happened in recent hours, temperatures will be considerably more restrained and some fogs or low clouds will appear, due to the marked thermal contrast between the ambient heat and the cold sea water. However, by the end of the weekend, a significant cool-down accompanied by showers will arrive.

Thursday: more heat and suspended dust

We wake up with little cold or very moderate cold, and a marked thermal inversion, with lower values at low altitudes than at high altitudes. For example, in Montserrat there has been a minimum of almost 16 ºC, while right next door, in Vacarisses (Vallès Occidental), it has dropped to 5 ºC. Temperatures will still rise further this Thursday, with very warm weather for the season. Most maximums will range between 25 and 30 ºC in the pre-coastal area and inland. The highest values are expected in Ponent and the Ebro interior, where the first 30 ºC of the year can be reached. Heat more typical of late spring or early summer than of April.

However, on the coast the mercury will once again be considerably more held back due to the regulating effect of a still cold Mediterranean Sea. The thermal contrast between the cold water and the very warm air mass we have above will cause the formation of new fogs or low clouds in coastal stretches. In the rest of the territory, the sun will dominate, with thin clouds and haze due to the presence of suspended dust.

Changes in sight

Temperatures will remain high until Saturday, but on the first day of the weekend, cloud cover will begin to increase, and in the afternoon, the first showers may arrive in the Pyrenees and Poniente.

This will be the prelude to the arrival of a cold air mass that, from Sunday onwards, will open the doors to the north wind and a significant drop in thermometers. A refresh that will be accompanied by instability, as rain may reach practically any point between Sunday and Monday. In the Pyrenees, the snowline will gradually lower to below 1,500 m. A significant change in weather that we will have to be monitoring.