Roma
Roma: Geografia e clima
Geografia
Rome sits on the Tiber about 25 kilometres from the Tyrrhenian Sea, in a volcanic landscape that shaped everything the city was built from.
The hills
The famous seven — Palatine, Capitoline, Aventine, Caelian, Esquiline, Viminal and Quirinal — are low spurs of volcanic tuff rising perhaps forty or fifty metres above the river plain, separated by valleys that were marshy before they were drained. They are less dramatic than the phrase suggests, but they were defensible and above the flood line, which is the whole reason the city is here.
The Tiber
Navigable from the sea to this point and fordable at the Tiber Island, which made this the meeting of a river route and a coastal road. The river flooded catastrophically and repeatedly until the high embankment walls were built in the 1870s, which ended the floods and also cut the city off from its river.
Volcanic rock
The Alban Hills to the south-east are a volcanic complex, and their products built Rome: tuff for blocks, travertine from Tivoli for facing, and above all pozzolana, volcanic ash that reacts with lime to make a concrete that sets underwater and is still standing after two thousand years.
Water
Springs in the surrounding hills fed eleven aqueducts, several of which still deliver water to the fountains today.
Twenty metres down
The modern street level sits several metres above the ancient one across much of the centre — the accumulated debris of collapse, flood silt and rebuilding. It is why the Pantheon is approached down steps that were once up them, why the Forum lay buried as a cow pasture until the nineteenth century, and why every excavation for a metro line turns into an archaeological dig that adds years to the schedule.
The campagna
The rolling country around the city, malarial until the twentieth century and now largely suburb.
Clima
Rome has a Mediterranean climate, with a genuinely hot summer and a winter that is mild rather than cold.
Summer
June to August is hot and dry: highs of 30 to 34°C, frequently higher, with very little rain and strong sun. The stone and asphalt hold heat, so the city is several degrees warmer than the surrounding countryside and stays warm into the night. Romans leave in August, and many small restaurants and shops close for two or three weeks around Ferragosto on the 15th.
Winter
December to February is mild and damp: 12 to 14°C by day, 3 to 5°C at night, with most of the year’s rain falling as heavy showers rather than persistent drizzle. Snow is rare enough that a few centimetres shuts the city.
Spring and autumn
April, May, September and October are the best months by a wide margin — warm days, cool evenings, and light that makes the stone look the way it does in paintings.
Rain
Around 800 millimetres a year, more than London, concentrated between October and December.
The wind
Two winds matter. The tramontana comes cold and dry off the Apennines in winter and produces the brilliantly clear days when the mountains are visible from the Janiculum. The scirocco arrives from the Sahara at any season, warm, heavy and sometimes carrying reddish dust that films the cars, and Romans blame it for headaches and bad temper.
Practical effect
In summer, do the archaeology at opening time, take the middle of the day indoors or over a long lunch, and come out again after five. The Forum and Colosseum have almost no shade.