Climate: hot summers, autumn rains, air quality

The yearly cycle

Rome has a Mediterranean climate with maritime influence. Summer is the most stable period: long days, almost constant sunshine from June to early September and daytime highs that often exceed 30 °C in July and August, with nights staying warm in the centre because of the heat-island effect. The "ponentino", the afternoon sea breeze, brings relief especially to the western districts.

Rain arrives in autumn: October, November and December are the wettest months, with short intense episodes that can flood underpasses and streets. Winter is mild and snow in the city is exceptional (the last significant accumulation was in February 2018). Spring is changeable but generally dry from May.

Air and traffic restrictions

Air quality is monitored by ARPA Lazio; some traffic stations exceed the daily PM10 limit on several days a year (see data). To contain emissions, Roma Capitale applies the "Fascia Verde" ZTL, a wide area that permanently excludes, Monday to Saturday, the most polluting vehicles (petrol Euro 0-2, diesel Euro 0-3 for residents). During winter peaks additional bans may be triggered: anyone arriving with an old car should check its emission class before driving.

Other natural hazards

Seismic risk is low to moderate for the municipal territory; the events felt in recent decades had their epicentres in the Apennines. Flood risk mainly concerns areas along the Tiber and Aniene rivers and the coast: Tiber floods are contained by the nineteenth-century embankments, but heavy rain causes local flooding in the outskirts.