Climate and natural hazards

The coast and the Roman countryside have a Mediterranean climate with mild, rainy winters and hot, dry summers; in Rome summer heatwaves regularly exceed 35 °C and the number of tropical nights is rising. The Pontine plain is humid and hot. Inland the climate changes quickly: Rieti, Leonessa and Amatrice have cold winters with snow; Terminillo (2,217 m) is the Romans' ski resort. The Tuscia around Viterbo has a cooler hill climate than the coast, with winter fog.

Seismic and volcanic risk

Civil Protection classifies the Rieti Apennines (Amatrice, Accumoli, Cittareale) and part of inland Ciociaria (Sora, Cassino) in seismic zone 1, most of the rest of the region in zone 2 and Rome and the coastal strip in zone 3. The earthquake of 24 August 2016 (magnitude 6.0) destroyed Amatrice and Accumoli, in the Rieti area, and reconstruction is still under way. The Colli Albani are a quiescent volcanic complex monitored by INGV; it has had no eruptions in historical times but shows gas emissions (Cava dei Selci, Tor Caldara) that INGV documents.

Water, fires, air

Rome is supplied by the Peschiera and Capore aqueducts, but in summer 2017 the drop in Lake Bracciano led to announced rotating water cuts, which were then avoided by allowing reduced, time-limited withdrawals from the lake. The Tiber and Aniene periodically flood the riverside areas of Rome. Along the coast between Fiumicino and the Circeo, scrub and pine-forest fires break out in summer. Air quality is critical in Rome and in the Sacco valley (Frosinone), where exceedances of PM10 limits are among the most frequent in Italy according to ARPA Lazio data.