Red alerts for extreme heat are in place in most of Italy's main cities as a heatwave intensifies in Europe. Temperatures are expected to peak on Wednesday, with 23 cities on high alert – from Trieste in the north-east to Messina in the south-west. Wildfires are also raging across the continent, including in Greece and the Swiss Alps.
 
Millions of people in the northern hemisphere are being affected by scorching temperatures. It is being caused by a high-pressure system bringing warmer, tropical air, south of a jet stream currently stuck over central Europe. Parts of the Italian islands of Sardinia and Sicily will be the hottest again, with highs of around 46C or 47C.
 
The Italian health ministry has asked emergency rooms across the country to activate so-called heat codes, assigning a separate group of medical staff to treat people who come in with symptoms caused by the heat.