Heatwave alert spreads to 51 departments

With temperatures reaching 38C in the south-west, the orange heatwave alert has been extended from 16 department to 51 and now covers a vast block of western and central France.

Residents are advised to be aware of their exposure to the sun and heat and to drink plenty of water but not alcohol, coffee or sweet, fizzy drinks. People should also wash often, especially faces, to feel fresher. Samu emergency medical teams reported a 15-20% rise in call-outs yesterday.

Similar temperatures are expected but skies will fill with cloud and turn heavy and thunderstorms are likely in the Pyrénées and Massif Central by the end of the day. These will not be widespread at first but risk being heavy with hail.

A bright, sunny day is also expected to cause a peak of air pollution in Paris, especially in the south-west of the city and suburbs. Paris mayor Anne Hidalgo is also keeping several of the city's parks open at night to give cool locations to go to.

Temperatures are about 10C above seasonal norms and will be from 31-35C across a large part of the country, locally 36 or 37C in the shade in western and central areas – but 25-30C on the Channel and Mediterranean coasts.

Weather forecasters warn that there will be no relief before Friday with cooler weather coming from the west and north-west but the south, eastern centre and south-west will stay hot.

France Bleu showed the daily and nightly minimum temperatures for a heatwave alert to be put in place (graphic in here)

June heatwave alerts are unusual – they generally come in July or August – and this is the first since 2005. The canicule heatwave alert is put in place when nights have particularly high temperatures over more than a couple of days, giving no relief. A very long heatwave in 2003 is estimaged to have caused 193,000 deaths.

Météo France is forecasting a hot summer and June is already shaping up to be among the three warmest since records were kept.