Italy was set to experience its first heatwave of the summer this week, with temperatures of around 41°C forecast in parts of Puglia, Sicily and Sardinia, and highs of 40°C in Rome.

On Wednesday, the hottest part of the country was Foggia, in Puglia, with mercury levels reaching 40°C, according to forecasters from Italian weather website IlMeteo.it. The southern provinces of Caltanissetta, Matera, Nuoro, Syracuse and Taranto were all expected to see temperatures of 38-39°C.

Temperatures at the start of the week were already 10 degrees above seasonal averages on Monday, said Antonio Sanò, meteorologist and founder of Italian weather website IlMeteo.it.

READ ALSO: Italy braces for first summer heatwave with highs of up to 40C

Though it’s hard to accurately predict the weather more than 10 days in advance, the data available so far indicates a warmer-than-average summer across Europe.

To warn citizens of the potential health threat posed by the weather, Italy’s health ministry issues three-day alerts, updated daily, with heat risk levels for the country’s major cities.

A ‘red’ alert is the highest-level warning, followed by amber for medium-high and yellow for a medium-low risk alert.

Green is level zero, signifying no heat risk.

Here’s what the country is set to look like as of Thursday, June 20th:

Perugia was the only city on red alert for Thursday, while amber alerts were in place for 15 cities, including Rome, Naples, Florence, Bologna and Palermo.

Seven other cities, including the regional capitals of Genoa, Milan, and Bolzano, were under yellow alerts, while Turin, Verona, Venice and Civitavecchia were the only urban centres marked as zero-risk.

Here’s the government’s alert for the following day, Friday, June 21st:

Six other central and southern cities were forecast to join Perugia in the red zone by Friday, including Rome and Palermo.

The highest-level red alert means weather conditions may be harmful to the health of the general population, while medium-level warnings indicate conditions that may pose a risk to the elderly, sick or very young.

The health ministry recommends avoiding outdoor activity and exposure to the sun in the middle of the day.