Italy to place all 27 of its major cities on highest heat alert

People cooling off near the Colosseum in Rome. Authorities have warned people to avoid direct sunlight during the hottest hours, to stay indoors where possible and drink at least 1.5 litres of water a day. Photograph: Remo Casilli/Reuters

Italy is to place all of its 27 major cities, from Trieste in the north to Palermo in the south, under the highest heat alert as the fourth heatwave to hit the country this summer intensifies.

A red alert means there is a higher chance of an emergency owing to the health risk posed by prolonged extreme temperatures to the entire population.