Spain is heading into its third heatwave of the year, with temperatures forecast to reach 44 degrees Celsius, the national weather service AEMET forecast Monday.

Dangerously high temperatures are expected from Tuesday, particularly in the south-east, the north-east, and the interior of the Mediterranean holiday island of Mallorca.

The areas expected to be hardest hit are cities along the Guadalquivir River valley in Andalusia in the south and the Ebro River valley in Aragon in the northeast.

According to forecasts, the highest temperature could be recorded on Thursday in the Andalusian town of Macael.

AEMET issued a red warning, its highest alert level, for parts of Andalusia.

On Mallorca, temperatures in Palma could climb to 39 degrees Celsius (102.2 degrees Fahrenheit) by Tuesday, while inland areas may reach 40 degrees by Friday. An orange warning has been issued there and across other parts of mainland Spain.

AEMET warned that the heat will increase the risk of wildfires, as vegetation is dry and flammable.

Greece is currently experiencing its first major heatwave of the summer after a relatively mild start to the season. Much of the country is expected to see 40-41 C, with some inland areas reaching 42-43 C.

According to the EMY national weather service, the heat is expected to begin easing from the north on Thursday, although southern parts of the country will likely remain hot for a longer period.

The Greek mainland is forecast to be the most severely affected. Most islands, by contrast, are expected to experience somewhat milder temperatures of 35-37 C.

As a precaution, several major Greek cities have opened air-conditioned public halls and community spaces during the day to help those without air conditioning at home.