According to the IPMA, the yellow warning will be in effect between 9 am on 11 June and 6 pm on 13 June due to persistent high maximum temperatures.

The yellow warning, the least severe on a scale of three, is issued whenever there is a risk to certain weather-dependent activities.

Mainland Portugal will experience high temperatures until 13 June, with the maximum ranging from 27 to 38 degrees on 11 June and from 35 to 40 degrees Celsius on 12 June.

On 11 June, a "more pronounced" increase in maximum temperature is expected, with values rising by about 10 degrees Celsius in some places.

According to IPMA, 12 June will be the hottest day, with maximum temperatures ranging between 35 and 40 degrees Celsius across most of the country.

The minimum temperature is also expected to rise across the country, with some locations forecast to reach or exceed 20 degrees Celsius until the evening of 13 June.

According to the Institute, the weather "will be conditioned by an anticyclone located northeast of the Azores archipelago, extending in a ridge to France, and by a depression trough extending from North Africa to the Iberian Peninsula."

"The combined action of these two centres of action will lead to the transport of a mass of hot, dry air over the Iberian Peninsula, which will be responsible for a sharp increase in temperature values," according to the institute.