Italy has a
variety of climate systems. The inland northern areas of Italy (for example
Turin, Milan, and Bologna) have a relatively cool, mid-latitude version of the
Humid subtropical climate (Köppen climate classification Cfa), while the
coastal areas of Liguria and the peninsula south of Florence generally fit the
Mediterranean climate profile (Köppen climate classification CSa).
Between the
north and south there can be a considerable difference in temperature, above
all during the winter: in some winter days it can be −2 °C (28 °F) and snowing
in Milan, while it is 8 °C (46.4 °F) in Rome and 20 °C (68 °F) in Palermo.
Temperature differences are less extreme in the summer.
The east
coast of the Italian peninsula is not as wet as the west coast, but is usually
colder in the winter. The east coast north of Pescara is occasionally affected
by the cold bora winds in winter and spring, but the wind is less strong here
than around Trieste. During these frosty spells from E–NE cities like Rimini,
Ancona, Pescara and the entire eastern hillside of the Apennines can be
affected by true "blizzards". The town of Fabriano, located just
around 300 m (984 ft) in elevation, can often see 0.5–0.6 m (1 ft 7.7 in–1 ft
11.6 in) of fresh snow fall in 24 hours during these episodes.
On the coast
from Ravenna to Venice and Trieste, snow falls more rarely: during cold spells
from the east, the cold can be harsh but with bright skies; while during the
snowfalls that affect Northern Italy, the Adriatic coast can see a milder
Sirocco wind which makes snow turn to rain—the mild effects of this wind often
disappear just a few kilometres inside the plain, and sometimes the coast from
Venice to Grado sees snow while it is raining in Trieste, the Po River mouths
and Ravenna. Rarely, the city of Trieste may see snow blizzards with
north-eastern winds; in the colder winters, the Venice Lagoon may freeze, and
in the coldest ones even enough to walk on the ice sheet.
Summer is
usually more stable, although the northern regions often have thunderstorms in
the afternoon/night hours and some grey and rainy days. So, while south of
Florence the summer is typically dry and sunny, in the north it tends to be
more humid and cloudy. Spring and Autumn weather can be very changeable, with
sunny and warm weeks (sometimes with Summer-like temperatures) suddenly broken
off by cold spells or followed by rainy and cloudy weeks.
In the north precipitation is more evenly distributed
during the year, although the summer is usually slightly wetter. Between
November and March the Po valley is often covered by fog, especially in the
central zone (Pavia, Piacenza, Cremona and Mantua), while the number of days
with lows below 0 °C (32 °F) is usually from 60 to 90 a year, with peaks of
100–110 days in the mainly rural zones. Snow is quite common between early December
and early March in cities like Turin, Milan and Bologna, but sometime it
appears in late November or late March and even April. In the winter of
2005–2006, Milan received around 0.75–0.8 m (2 ft 5.53 in–2 ft 7.50 in) or
75–80 cm (29.5–31.5 in) of fresh snow, Como around 1 m (3 ft 3.37 in) or 100 cm
(39.4 in), Brescia 0.5 m (1 ft 7.69 in) or 50 cm (19.7 in), Trento 1.6 m (5 ft
2.99 in) or 160 cm (63.0 in), Vicenza around 0.45 m (1 ft 5.72 in) or 45 cm
(17.7 in), Bologna around 0.3 m (11.81 in) or 30 cm (11.8 in), and Piacenza
around 0.8 m (2 ft 7.50 in) or 80 cm (31.5 in).