Throughout the first week of October temperatures will be above average for the month across the mainland. Regions like Évora may reach 35 degrees Celsius Wednesday.

Cristina Simões, a meteorologist at the IPMA, told Público says that it is almost certain that meteorological stations will register a heat wave situation, a period of at least six consecutive days in which the daily maximum temperature is five degrees Celsius higher than the average value of the maximums.

The meteorologist says that, as usual, the heat should be more pronounced inland than on the coast. The hottest day this week is set to be Wednesday 5 October, with temperatures of 35ºC in Évora, 34ºC in Santarém, 33ºC in Beja, Portalegre and Setúbal, 32ºC in Castelo Branco and 30ºC in Lisbon. In the districts with the cooler temperatures, it will still be hot: 23ºC are expected in Viana do Castelo and 24ºC in Aveiro and Porto.

Cristina Simões says that the temperature should drop slightly from Thursday, the day from which the maximum should, on average, be around 25 to 26 degrees, but these remain “pleasant” values. Even after the general drop in temperatures, Évora and Santarém should remain just above 30ºC.

Dust clouds

October also begins with the return of dust from North Africa. “Yesterday [Sunday], at the end of the afternoon, this yellow sky was already being observed in the central and southern regions of the country”, says Cristina Simões, stressing that this Monday should be the day with the highest concentration of this dust in the atmosphere. “Tomorrow [Tuesday], it may still be visible, but it should gradually start to lose expression.”

The dust came from the African Sahara Desert and has been suspended in the atmosphere as a result of sandstorms. This dust should not raise the same concerns it did back in March, when large amounts of dust from the Sahara led to a drop in maximum temperatures and worsened air quality.