Italy's climate, in 1991-2020 numbers

Between Passo Rolle in the Dolomites, at a mean annual 37.8°F (3.2°C), and Trapani in western Sicily, at 64.6°F (18.1°C²), Italy spans almost 15°C of mean temperature, which is why a national answer about the weather is always the wrong answer.

The numbers here are thirty year normals, not forecasts

Every figure below is a WMO Climatological Standard Normal for 1991-2020, measured at stations of the Italian Air Force weather service, of which Italy submitted 84 to the World Meteorological Organization. A month is published only when at least 24 of the 30 years pass validation.

That rule matters more than it sounds. Where a station fails it, no annual total exists at all, and any site that prints one for those places has added it up itself.

From an alpine pass to a Sicilian airfield

Passo Rolle sits at 2,004 m (6,575 feet) and averages 37.8°F (3.2°C) over the year, with February at 24.1°F (-4.4°C) and July at 53.4°F (11.9°C³). Five months of the year have a mean below freezing.

Naples Capodichino averages 62.8°F (17.1°C²), Trapani Birgi 64.6°F (18.1°C²), Ustica 64.4°F (18.0°C). In January the mean runs from 25.0°F (-3.9°C) at Passo Rolle to 52.5°F (11.4°C²) at Trapani. In July the mean maximum runs from 61.2°F (16.2°C²) at the pass to 90.1°F (32.3°C²) in Florence, the hottest of the big cities because of the basin it sits in.

Rain falls in opposite seasons north and south

The Alps take their maximum in summer: Paganella, at 2,125² m (6,972 feet), records 830.1 mm² a year with 109.5 mm⁵ in July and 20.1 mm⁵ in January. Dobbiaco, an inhabited valley floor at 1,222² m (4,009 feet), peaks in July at 122.8 mm⁴.

The south does the reverse. Trapani Birgi collects 488.9 mm² a year, of which 2.9 mm falls in July and 74.6 mm in November; Ustica takes 525.7 mm² on the same shape. In between, the Po plain has two maxima, one in autumn and one in late spring, and no dry season: Milan Linate spreads 722.4 mm² over 73.9⁷ days with at least 1 mm.

One number we cannot reconcile, and we say so

Milan Linate's 722.4 mm² annual rainfall in the 1991-2020 series is well below the older 1971-2000 series for the same station, which sits near 920 mm⁷. The gap has not been explained: it could be instrument change, real decline, or different validation rules.

If you find a Milan rainfall figure near 920 mm⁷, it is probably the older series rather than an error. Both cannot be used in the same sentence.

What the airport stations cannot tell you

Weather stations sit at airports, so the 90.1°F (32.3°C²) mean July maximum recorded at Florence Peretola understates what a July afternoon feels like inside the city. Airfields are flat, ventilated and outside the built-up core: the urban heat island is real and this dataset does not quantify it.

Two more gaps are worth naming. Palermo has no complete 1991-2020 series, so western Sicily is represented here by Trapani, 56 miles (90 km) west, and by the island of Ustica; neither should ever be labeled Palermo. And Rome Ciampino has no annual rainfall total because June, July and August fail the validity rule, so the 622.6 mm² quoted for Rome is Fiumicino, on the coast, which is drier than the city. City by city numbers are on Rome, Venice and the Alps.

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