Climate of Italy

Summer in Costa Smeralda, Sardinia

The Italian climate is influenced by the large body of water of the Mediterranean Seas that surrounds Italy on every side except the north. These seas constitute a reservoir of heat and humidity for Italy. Within the southern temperate zone, they determine a Mediterranean climate with local differences due to the geomorphology of the territory, which tends to make its mitigating effects felt, especially in high pressure conditions.[3]

In addition to Mediterranean influences, the Italian climate is partly affected by the western currents, especially in the intermediate seasons, also by the dynamics in the Atlantic Ocean, with its cyclones that travel from west to east, driven by the zonal circulation and more generally by the reciprocal position, on a synoptic level, of the Azores anticyclone and the African subtropical anticyclone.[4] The cold winter airs, are in part influenced by the mountain ranges of the Alps and the Apennines.[5] The mitigating effect of the Mediterranean is added to this condition with a tendency to reinvigorate, due to the transfer of sensible heat and humidity, the weakened perturbations from the west or with the formation of Mediterranean Low or Mediterranean cyclogenesis.[6]

Conditions on the coast are different from those in the interior, particularly during winter months when the higher altitudes tend to be cold, wet, and often snowy. The coastal regions have mild winters and warm and generally dry summers, although lowland valleys can be quite hot in summer. Average winter temperatures vary from 0 °C (32 °F) on the Alps to 12 °C (54 °F) in Sicily, so average summer temperatures range from 20 °C (68 °F) to over 25 °C (77 °F). Winters can vary widely across the country with lingering cold, foggy and snowy periods in the north and milder, sunnier conditions in the south. Summers can be hot and humid across the country, particularly in the south while northern and central areas can experience occasional strong thunderstorms from spring to autumn.[7]

Lake Pranda in Tuscan–Emilian Apennines in October.

Nature reserve Paneveggio in Trentino in March.

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 wind can be harsh but with bright skies. 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.[8] Further south, snow may occur inland but it rarely happens at sea level. However, snow has been recorded as far south as Salento. Winters are generally milder in the coastal areas of the south, Sicily and Sardinia. The west coast of Italy has rainier winters while the east is more exposed to the cold Bora winds.

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. Even if the temperatures are similar throughout the country, the humidity can make the northern plains particularly uncomfortable. Hot weather can occur practically anywhere in Italy during the summer months. 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.

Map of the average annual sunshine duration in Italy (in hours)

  < 1,799 h

  1,800-1,999 h

  2,000-2,199 h

  2,200-2,399 h

  2,400-2,599 h

  > 2,600 h

Map of the average annual cloud cover in Italy (in okta)

  < 2,750 okta

  2,750 - 3,000 okta

  3,000 - 3,250 okta

  3,250 - 3,500 okta

  3,500 - 3,750 okta

  3,750 - 4,000 okta

  4,000 - 4,250 okta

  4,250 - 4,500 okta

  > 4,500 okta

Based on the maps on sunshine duration[9][10] and on global solar irradiance[11] in Italy, the areas with the highest values ​​are the coasts of Sardinia, the western and southern coastal strip of Sicily, the whole of Apulia south of Bari, and the coastal strips of the southern Tuscan Archipelago. All these areas have values ​​of more than 2,600 hours of sunshine per year, with an average of more than seven hours per day.

On average, the northern and eastern coastal strip of Sicily, the innermost areas of Sardinia, the entire western peninsular coast to the south of Livorno, including the flat and hilly areas of the hinterland, the Ionian coast between Calabria and Basilicata, the inland areas of Lucania, the Adriatic coasts of Molise and the whole of northern Apulia, receive between 2,400 and 2,600 hours of sunshine per year (between 6.5 and seven hours per day).

Values between 2,200 and 2,400 hours of sunshine per year (between 6 and 6.5 hours per day) are recorded in the innermost areas of Sicily, in some sections of the Calabrian Ionian coast and in the corresponding inland areas, along the Adriatic coast of Abruzzo, in Liguria, Versilia, inland areas of northern and eastern Tuscany, in Umbria and in the hinterland of southern Lazio and Campania. All the other areas north of the imaginary oblique transversal line, drawn between the area immediately north of the city of Genoa and the border between Marche and Abruzzo, record annual average values ​​that do not reach 2,200 hours, or less than six hours per day.

The highest annual average values ​​in the network of pyranometric stations relating to global solar irradiance are higher than 18 MJ/m² (0.46 kWh/sq ft) and concern the southern and south-eastern extremities of Sicily. Average annual values between 16 MJ/m² (0.41 kWh/sq ft) and 18 MJ/m² (0.46 kWh/sq ft) are recorded over a large part of the Aosta Valley, on the western alpine extremity of Piedmont, on the island of Pianosa, on the coastal and sublittoral areas of the middle and southern Lazio, in the south-central Apulia, Calabria, Sardinia and most of Sicily (including the islands of Ustica, Pantelleria and Lampedusa).

Average annual values between 14 MJ/m² (0.36 kWh/sq ft) and 16 MJ/m² (0.41 kWh/sq ft) affect western Liguria, a large part of Tuscany and central-northern Lazio, a large part of the Marche, Abruzzo and Molise, Campania, Basilicata, northern Puglia and north-eastern Sardinia. Average annual values between 12 MJ/m² (0.31 kWh/sq ft) and 14 MJ/m² (0.36 kWh/sq ft) occur in central-eastern Piedmont, eastern Liguria, Lombardy, Trentino-Alto Adige, Veneto, Friuli-Venezia Giulia, most of Emilia-Romagna and on the Apennine ridge between Emilia, Tuscany, Umbria, Marche and Lazio. Average annual values ​​of less than 12 MJ/m² (0.31 kWh/sq ft) are recorded in an area of ​​the Tuscan-Emilian Apennines which includes the highest peaks.

Cloud cover generally tends to reach the lowest average values ​​in the month of July, while the highest average values, according to the different climatic zones, can affect several months between late autumn and the first part of spring, with the highest average values ​​in most of the territory recorded in November.[12]

Lake Garda in autumn.

Fog in Po Valley is frequent during the winter time

In the south, summer marks a distinct dry season, characteristic of Mediterranean climates. This includes cities such as Naples, Rome, Bari, and Palermo. 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.[13]

Snow is quite common between early December and early March in cities like Turin, Milan and Bologna, but sometimes 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) [14]

Often, the largest snowfalls happen in February, sometime in January or March. In the Alps, snow falls more in autumn and spring over 1,500 m (4,921 ft), because winter is usually marked by cold and dry periods; while the Apennines see many more snow falls during winter, but they are warmer and less wet in the other seasons.

Both the mountain chains can see up to 5–10 m (16 ft 4.85 in – 32 ft 9.70 in) or 500–1,000 cm (196.9–393.7 in) of snow in a year at 2,000 m (6,562 ft). On the highest peaks of the Alps, snow may fall even during mid summer, and glaciers are present.

Tuscan landscape in Val d'Orcia during summer.

Summer temperatures are often similar north to south. July temperatures are 22–24 °C (71.6–75.2 °F) north of river Po, like in Milan or Venice, and south of river Po can reach 24–25 °C (75.2–77.0 °F) like in Bologna, with fewer thunderstorms; on the coasts of Central and Southern Italy, and in the near plains, mean temperatures goes from 23 °C to 27 °C (80.6 °F). Generally, the hottest month is August in the south and July in the north; during these months the thermometer can reach 38–42 °C (100.4–107.6 °F) in the south and 32–35 °C (89.6–95.0 °F) in the north; Sometimes the country can be split as during winter, with rain and 20–22 °C (68.0–71.6 °F) during the day in the north, and 30–40 °C (86–104 °F) in the south; but, having a hot and dry summer does not mean that Southern Italy will not see rain from June to August. Thunderstorms, while much more common in the humid north, occasionally also occur in the south. High humidity may keep nighttime temperatures high in Italy's cities during the summer months.

The coldest month is January: the Po valley's mean temperature is between −1–1 °C (30.2–33.8 °F), Venice 2–3 °C (35.6–37.4 °F), Trieste 4 °C (39.2 °F), Florence 5–6 °C (41.0–42.8 °F), Rome 7–8 °C (44.6–46.4 °F), Naples 9 °C (48.2 °F), and Cagliari 12 °C (53.6 °F). Winter morning lows can occasionally reach −30 to −20 °C (−22.0 to −4.0 °F) in the Alps, −14 to −8 °C (6.8 to 17.6 °F) in the Po valley, −7 °C (19.4 °F) in Florence, −4 °C (24.8 °F) in Rome, −2 °C (28.4 °F) in Naples and 2 °C (35.6 °F) in Palermo. In cities like Rome and Milan, strong heat islands can exist, so that inside the urban area, winters can be milder and summers more sultry.

On some winter mornings it can be just −3 °C (26.6 °F) in Milan's Piazza del Duomo while −8 to −9 °C (17.6 to 15.8 °F) in the metropolitan outskirts, in Turin can be just −5 °C (23.0 °F) in the city centre and −10 to −12 °C (14.0 to 10.4 °F) in the metropolitan outskirts.

Syracuse, Sicily, where the highest temperature ever in Europe was recorded, 48.8 °C (119.8 °F)

The record low temperature in Italy is −49.6 °C (−57.3 °F), recorded on 10 February 2013 in the Alps on the Pale di San Martino plateau, in Trentino-Alto Adige,[73] while near sea level is −24.8 °C (−12.6 °F), recorded on 12 January 1985 at San Pietro Capofiume, frazione of Molinella, in Emilia-Romagna.[74] The lowest temperature record for an inhabited place is −37.4 °C (−35.3 °F), recorded on 15 February 2012 in Rocca di Mezzo, Abruzzo, in the Apennines.[75]

The maximum snow depth was recorded in March 1951 in the Alps at the meteorological station of Lake D'Avino, in Piedmont, with a value of 1,125 cm (443 in).[76] The maximum snowfall in 24 hours is 181 cm (71 in), recorded in the Apennines in the village of Roccacaramanico, frazione of Sant'Eufemia a Maiella (Majella massif), Abruzzo, on 15 January 1951.[77]

The village of Musi, frazione of the municipality of Lusevera, Friuli Venezia Giulia, with an annual average precipitation of 3,313 mm (130.4 in) (with a record of 5,406 mm (212.8 in) in 2014) is the wettest place in Italy.[78] The maximum rainfall in 24 hours was recorded in Bolzaneto, a quarter of Genoa, Liguria, on 10 September 1970 with a value of 948 mm (37.3 in).[79] However, there are many daily rainfall records around Italy exceeding 500 mm (20 in).[80][81]

In the south, Sicily has experienced highs of 46 °C (114.8 °F) in some hot summers.[82] There are three candidates for the highest temperature: 47.0 °C (116.6 °F) recorded in Foggia in Apulia on 25 June 2007, and 48.5 °C (119.3 °F) recorded in Catenanuova in Sicily on 10 August 1999.[83][84] The latter is not official, and generally considered dubious. The official highest temperature in Europe was recorded in Athens on 10 July 1977, at 48.0 °C (118.4 °F).[85] The record of 48.8 °C (119.8 °F) in Syracuse in Sicily, on 11 August 2021, the highest temperature ever recorded in Europe, will be analyzed by WMO.[86]

2009 Messina floods and mudslides

Italy, like other parts of the globe, has been subject in the past to climate changes on a planetary scale (for example glaciations and interglacial periods, Little Ice Age). The current climate changes (global warming) have also involved Italy.

In particular, compared to the 1960s and 1970s, in which even on a global level there was a slight cooling of the climate (dominated in Europe by the Azores anticyclone and the Russian-Siberian anticyclone), from the mid-1980s onwards there was a recorded increase in the average temperature with increasing influence of the African subtropical anticyclone starting from the 2000s and an increase in extreme phenomena such as heat waves, alluviums and retreat of alpine glaciers.[87][88]

• Climate of Ancient Rome
• Geography of Italy

• Average climatic data of cities in Italy