The month of December in mainland Portugal kicked off with typical winter temperatures due to the presence of polar air, producing frost in some parts of the interior.

Temperatures are expected to drop, especially the highs, which will make the days cooler, says Alfredo Graça, geographer and editor at Meteored Portugal.

On Wednesday, a few isolated and scattered showers are expected in the centre and south of mainland Portugal. It will be a day of transition, as a new front will arrive at the end of the day and, as it penetrates the geography of mainland Portugal from the north-west, it will produce locally heavy rainfall in Minho, and in parts of the Douro Litoral and north-eastern Transmontano. Temperatures will rise across the country, with highs standing out.

On Thursday, the rain will be heavier from the north to the south of the country. Mainland Portugal will be under the polar jet stream - the conveyor belt of fronts and depressions - and at the same time will be impacted by an atmospheric river linking the country to the Caribbean.

This meteorological panorama will cause widespread, locally heavy and persistent rain in the Minho, Douro Litoral, in mountainous areas of the Aveiro and Viseu districts and in parts of the Cordillera Central. The possibility of thunderstorms is not ruled out in some parts of the country.