The weather outlook indicates a gradual and sustained rise in temperatures throughout the week, with the most severe impact expected in the country's interior, where maximum temperatures are forecast to exceed 40ºC once again.

According to data from the specialised weather portal Tempo.pt, this situation stems from a very hot air mass settling over the Iberian Peninsula, reinforced by an intensifying anticyclonic ridge originating in North Africa.

The combination of these atmospheric factors will result in highly stable conditions, clear skies, strong solar radiation, and a progressive build-up of heat in the atmosphere.

Projections based on European Centre for Medium-Range Weather Forecasts (ECMWF) models indicate upper-air temperature anomalies ranging from 8ºC to 12ºC above the seasonal average, underscoring the severity of the incoming air mass.

Maximum temperatures will rise across the board, with the northern, central, and southern interior regions bearing the brunt of the impact, particularly in the Alentejo, the Tagus Valley, and various parts of the central interior, where there is a high probability that temperatures will reach or exceed 40°C.

Conversely, oceanic influence, driven by westerly and northwesterly winds in the afternoon, will continue to temper the heat along the coast, although temperatures will still rise in central and southern coastal areas; a temperature difference of more than 10°C is expected between the interior and the coast.

Near-calm wind conditions in the interior will favour heat retention, while atmospheric stability will preclude the risk of widespread thunderstorms, keeping the weather predominantly dry during a heatwave that, according to current models, is set to last at least until 22 July.