Italy's African heatwave peaks at 40°C, 18 cities under red alert; cool air and violent storms to follow from Wednesday
Temperatures soared to 40°C across northern Italy and Tuscany on 28 June, with Milan and Rome over 10°C above seasonal norms. The health ministry placed 18 cities on maximum alert as overnight lows stayed above 24°C, worsening sleep and cardiovascular stress. Cooler Atlantic air is expected to trigger severe thunderstorms and hail from 1 July.
Peak of the heatwave
The African-origin anticyclone, nicknamed Caronte by Italian meteorologists, pushed temperatures to their highest levels yet on Sunday 28 June and Monday 29 June. Daytime highs reached 40°C across the internal plains of the north and in Tuscany, while central and southern regions saw up to 38°C. The freezing level rose above 4,500 metres, reaching 5,000 metres over the Alps, a value typical of tropical atmospheres.
In Milan we are over 10 degrees above average, in Rome almost 10°C higher, and in Paris there were almost 20 degrees above the historical norm, practically double the temperature, both minimum and maximum, something incredible.
Tropical nights and health risks
Nighttime temperatures have remained persistently high, exceeding 24–25°C in large urban areas and often staying above 30°C at midnight. Urban heat islands, where asphalt releases stored heat and vegetation is scarce, amplify the effect. The human body needs a room temperature around 20–25°C for restorative sleep; sleeping in a room at 27–29°C or higher forces the body to work harder to cool down, reducing deep sleep and increasing frequent awakenings. Over consecutive hot nights, fatigue accumulates, and vulnerable groups (children, the elderly, outdoor workers, people with chronic illnesses) face a higher risk of sudden illness and cardiovascular decompensation.
European heatwave claims lives
The exceptional heat is not confined to Italy. In France and Spain, dozens of deaths have been attributed to the extreme temperatures. Germany recorded a new national high of 41.5°C, and 40°C was also reported in Warsaw, Vienna and Budapest.
Cool air and storms on the horizon
The anticyclone’s grip will begin to weaken from Tuesday 30 June, when a disturbance from the Atlantic starts to graze northern Italy. A more decisive change arrives on Wednesday 1 July, as a pool of cooler air of north-Atlantic origin breaks into the Mediterranean. The contrast between the hot, humid low-level air mass and the arriving cold air aloft will fuel severe thunderstorms, large hail and damaging wind gusts.
This is not a major crisis for the season, but a classic thunderstorm break. Already next weekend, high pressure is set to reclaim Italian territory, albeit in a completely different form — the return of the Azores anticyclone.
- Heatwave peak: daytime highs reach 40°C in northern plains and Tuscany; freezing level at 5,000 m over Alps; 18 cities on red alert.
- Second day of peak heat; slight temperature drop in northwest but 40°C still possible in Emilia-Romagna, Veneto and Sardinia; heat thunderstorms on Alpine and pre-Alpine reliefs.
- First signs of weakening: unstable air arrives from the Atlantic, bringing thunderstorms to the Alps and northern regions; limited temperature decrease elsewhere.
- Cool, north-Atlantic air mass enters Mediterranean; temperatures drop 6–8°C across Italy; violent thunderstorms, hail and strong winds develop, initially in the north.
- Unstable air spreads to central and southern regions; risk of severe phenomena including hail and tornadoes continues; temperatures move below the 35°C threshold.
- Azores high pressure begins to rebuild over Italy, bringing a more temperate and stable weather pattern for the following weekend.
