Italy's fourth heatwave reached its summer peak on Monday, 4 August 2026. The Italian Ministry of Health has issued the bollino rosso for 25 of 27 monitored cities, the highest warning level in the national heat alert system. Only Reggio Calabria and Messina remain classified with a bollino arancione, indicating a risk for particularly vulnerable population groups but not yet the emergency level for the population as a whole. The red alert mode thus affects virtually the entire Italian peninsula from Bolzano to Palermo, with the two Sicilian and Calabrian cities as the sole exceptions.
The 25 cities on red alert
The cities carrying the bollino rosso on 4 and 5 August include Ancona, Bari, Bologna, Bolzano, Brescia, Cagliari, Campobasso, Catania, Civitavecchia, Firenze, Frosinone, Genova, Latina, Milano, Napoli, Palermo, Perugia, Pescara, Rieti, Roma, Torino, Trieste, Venezia, Verona and Viterbo. As ANSA summarises from the Ministry of Health bulletin, this is the highest number of cities simultaneously on red alert recorded so far in the summer of 2026. By comparison, on 30 July 2026, the first day of the fourth heatwave, only three cities were on red alert and 16 on orange. Within just a few days the situation has deteriorated dramatically, with no sign of the classic peak-and-decline pattern typical of a heatwave.
The bollino rosso, classified as Livello 3 in the Italian system, denotes emergency conditions with potentially adverse effects on the health of the entire population, not merely the classic at-risk groups such as elderly people, young children and those with chronic illnesses. The Ministry recommends avoiding physical exertion during the core hours between 11 a.m. and 6 p.m., keeping indoor spaces cool and drinking sufficient fluids. Those wishing to explore the recommended precautions in detail will find guidance on Italy's heat culture in our article on heat in Italy and background on the anticyclone situation in our piece on the fourth heatwave of 2026.
Plateau rather than peak: the scientific assessment
What is striking about the current situation is that it can no longer be described as a classic heatwave with a rising and falling pattern. Dino Zardi, Professor of Atmospheric and Climate Physics at the University of Trento, has told ANSA that the current phase should be understood less as a peak and more as a plateau: the daily temperature cycles have been repeating themselves almost identically for days, with maximum values consistently remaining above climatological averages. Night-time temperatures are also failing to allow any meaningful recovery, with lows of 27 to 28 degrees in northern Italian cities, further intensifying the subjective sense of strain.
The subtropical anticyclone from North Africa, which has dominated the weather pattern since late July, remains stable over the Mediterranean, permitting neither frontal passages nor periods of rain. As Meteo.it notes in its forecast for the coming days, the maximum temperatures in the inland zones of the Po Valley and central Italy will continue to range between 38 and 40 degrees, with urban heat islands occasionally exceeding even those figures. The combination of high humidity, absolute calm and intense sunshine makes this plateau, according to Italian meteorologists, one of the most gruelling phases of the summer of 2026.
North-south forecast through to the end of the week
For further developments, Italian meteorologists are expecting a divided picture. As Sky TG24 documents in its live bulletin, any first perceptible relief is not expected before the end of the week in the north, where an unstable weather system from the Alpine region could reach the northern Italian regions. The south is highly likely to remain under the heat dome well into the Ferragosto week, with temperatures at or above 38 degrees and continued tropical nights. As for the weather on Ferragosto itself, the traditional Italian public holiday on 15 August, forecasts remain uncertain at present, with a continuation of the heatwave as the baseline scenario that travellers and residents alike should factor into their plans.
For travellers, this means in practical terms that city-break conditions in Italy's great art cities will be pushing their limits over the coming days. Those visiting the Uffizi in Firenze, the Colosseum in Rome or the Vatican Museums are advised to make use of the early morning hours or late-evening openings and to avoid the core midday period. Alongside the heat itself, each additional day of the plateau also increases the wildfire risk across large parts of Italy, as the dryness of vegetation and persistently high temperatures are raising the early-warning levels of the EU civil protection agency EFFIS in several regions. Those with flexible plans may wish to retreat to the mountain regions of the Dolomiti or head to the coast, where conditions remain more bearable.
