PARIS -- Authorities in the Paris region have issued an alert for intense heat expected in the French capital and across Europe this week.

The alert level in Paris has been raised to "orange," the second-highest level.

France's national weather agency Meteo France said the heat wave beginning Monday is expected to last all week with temperatures of up to 40 C (104 F) across the country. The peak is expected Thursday.

In Paris, charity organizations are patrolling to provide water to homeless people and local authorities have places where they can seek shelter.

Meteorologists say the heat wave is caused by hot winds coming from the Sahara desert.

The alert system was introduced in France following the 2003 summer during which an estimated heat-related 15,000 deaths were recorded. (AP)