Climate - Aosta (Italy)

The climate of Aosta is moderately continental, with cold winters and warm summers.
The city is located at 580 meters (1,900 feet) above sea level, and is the capital of the smallest Italian region, Valle d'Aosta, located in the north-west of Italy, on the border with France and Switzerland.
All around, there are mountains that exceed 4,000 meters (13,100 ft): to the south, the Gran Paradiso massif, to the north-west, the Mont Blanc, the highest peak in Europe (on the border with France), and to the north, the Grand Combin (in Switzerland) and the Matterhorn (on the border with Switzerland).
The average temperature of the coldest month (December) is of 1.5 °C (34.7 °F), that of the warmest month (July) is of 22.2 °C (72 °F). Here are the average temperatures.

Precipitation amounts to 550 millimeters (21.5 inches) per year. It ranges from 30 mm (1.2 in) in the driest month (February) to 60 mm (2.4 in) in the wettest ones (May, October). Due to its position in a valley arranged from west to east and surrounded by high mountains (as also happens in the city of Sion in Switzerland), the city does not receive much rainfall. However, from time to time, there may be more abundant rains than usual. In October 2000, when there were floods in north-western Italy, almost 300 mm (12 in) of rain fell. Here is the average precipitation.

The winter is cold. There may be relatively mild periods, when Atlantic currents prevail, and other colder periods, when the temperature drops below freezing.
Although the winter is a fairly dry season, so snowfalls are not very frequent, they can sometimes be abundant.
In this season, cold air stagnates in the valley, especially when the wind is weak or absent. In December, when the sun is lower, it stays behind the mountains for a few hours, and this favors thermal inversion. In December 1990, after a not very intense cold spell, with snow on the ground and clear skies, the temperature dropped to -18 °C (-0.5 °F), with a maximum of -8 °C (17.5 °F), but at 1 pm it was still -12 °C (10.5 °F). However, the mountains to the north protect Aosta from cold waves, so the temperature almost never drops below -15 °C (5 °F).
Actually, the north-westerly wind that descends from the mountains, the föhn, can bring strong increases in temperature, which can reach 20 °C (68 °F) even in the middle of winter. In January 2007, it reached 23 °C (73.5 °F), with a minimum of 14 °C (57 °F).

The summer in Aosta is quite hot, with many sunny days, and possible thunderstorms in the afternoon or evening. Nights are usually cool.
Sometimes there can be short, very hot periods, in which highs can reach 35 °C (95 °F). In late June 2019, during a short heatwave of African origin, the temperature reached 40.4 °C (104.7 °F).

Best Time

The best time to visit Aosta runs from mid-May to mid-September, since it is the warmest and sunniest period of the year. Sometimes, it can be hot in July and August, while in other circumstances, nights can be cool or even a little cold even in these months, so it can be useful to bring a sweatshirt or sweater and a light jacket for the evening.

Aosta - Weather by month

Based on the period 1991-2020

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In January, the weather in Aosta is usually cold. The average temperature is of 1.5 °C (35 °F), with a minimum of -3.2 °C (26.2 °F) and a maximum of 6.2 °C (43.2 °F).
On the coldest nights of the month, the temperature usually drops to around -9.5 °C (15 °F). However, it dropped to -17.6 °C (0.3 °F) in January 2006.
On the warmest days of the month, the temperature usually reaches around 15 °C (59 °F). However, it reached 22.6 °C (72.7 °F) in January 2007.
Precipitation amounts to 40 mm (1.6 in), distributed over 6 days.
The day lasts on average 9 hours and 5 minutes.
The average humidity is 70%.
The average wind speed is 14 kph (9 mph).

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In February, the weather in Aosta is usually quite cold. The average temperature is of 4.2 °C (39 °F), with a minimum of -1.7 °C (28.9 °F) and a maximum of 10 °C (50 °F).
On the coldest nights of the month, the temperature usually drops to around -8 °C (18 °F). However, it dropped to -16.5 °C (2.3 °F) in February 2010.
On the warmest days of the month, the temperature usually reaches around 18.5 °C (65.5 °F). However, it reached 26 °C (78.8 °F) in February 2020.
Precipitation amounts to 25 mm (1 in), distributed over 4 days.
The day lasts on average 10 hours and 25 minutes.
The average humidity is 73%. Hence, the air is normally humid.
The average wind speed is 14 kph (9 mph).

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In March, the weather in Aosta is usually quite mild. The average temperature is of 8.4 °C (47 °F), with a minimum of 2.2 °C (36 °F) and a maximum of 14.6 °C (58.3 °F).
On the coldest nights, which normally occur at the beginning of the month, the temperature usually drops to around -3 °C (26 °F). However, it dropped to -8.7 °C (16.3 °F) in March 2006.
On the warmest days, which normally occur at the end of the month, the temperature usually reaches around 23.5 °C (74 °F). However, it reached 26.3 °C (79.3 °F) in March 2020.
Precipitation amounts to 30 mm (1.2 in), distributed over 4 days.
The day lasts on average 12 hours and 0 minutes.
The average humidity is 70%.
The average wind speed is 14 kph (9 mph).

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In April, the weather in Aosta is usually mild. The average temperature is of 11.7 °C (53 °F), with a minimum of 5.3 °C (41.5 °F) and a maximum of 18.1 °C (64.6 °F).
On the coldest nights, which normally occur at the beginning of the month, the temperature usually drops to around -0.5 °C (31 °F). However, it dropped to -4.6 °C (23.7 °F) in April 2017.
On the warmest days, which normally occur at the end of the month, the temperature usually reaches around 25 °C (77 °F). However, it reached 29.5 °C (85.1 °F) in April 2007.
Precipitation amounts to 50 mm (2 in), distributed over 6 days.
The day lasts on average 13 hours and 35 minutes.
The average humidity is 74%. Hence, the air is normally humid.
The average wind speed is 13 kph (8 mph).

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In May, the weather in Aosta is usually very mild. The average temperature is of 15.6 °C (60 °F), with a minimum of 9.7 °C (49.5 °F) and a maximum of 21.5 °C (70.7 °F).
On the coldest nights, which normally occur at the beginning of the month, the temperature usually drops to around 5 °C (41.5 °F). However, it dropped to -0.7 °C (30.7 °F) in May 2019.
On the warmest days, which normally occur at the end of the month, the temperature usually reaches around 28.5 °C (83.5 °F). However, it reached 32.2 °C (90 °F) in May 2007.
Precipitation amounts to 70 mm (2.8 in), distributed over 8 days.
The day lasts on average 15 hours and 0 minutes. So the days are long.
The average humidity is 76%. Hence, the air is normally humid.
The average wind speed is 12 kph (7 mph).

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In June, the weather in Aosta is usually warm. The average temperature is of 19.2 °C (67 °F), with a minimum of 13.3 °C (55.9 °F) and a maximum of 25.1 °C (77.2 °F).
On the coldest nights, which normally occur at the beginning of the month, the temperature usually drops to around 8.5 °C (47 °F). However, it dropped to 2.6 °C (36.7 °F) in June 2011.
On the warmest days, which normally occur at the end of the month, the temperature usually reaches around 32.5 °C (90.5 °F). However, it reached 40.4 °C (104.7 °F) in June 2019.
Precipitation amounts to 45 mm (1.8 in), distributed over 7 days.
The day lasts on average 15 hours and 40 minutes. So the days are long. June 21, the summer solstice, is the longest day of the year in the Northern Hemisphere.
The average humidity is 74%. Hence, the air is normally humid.
The average wind speed is 10 kph (6 mph).

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In July, the warmest month of the year, the weather in Aosta is usually warm. However, there are remarkable differences between night and day. The average temperature is of 22.2 °C (72 °F), with a minimum of 15.5 °C (59.9 °F) and a maximum of 28.8 °C (83.8 °F).
On the coldest nights of the month, the temperature usually drops to around 10.5 °C (51.5 °F). However, it dropped to 6.1 °C (43 °F) in July 2007.
On the warmest days of the month, the temperature usually reaches around 33.5 °C (92.5 °F). However, it reached 36.5 °C (97.7 °F) in July 2020.
Precipitation amounts to 35 mm (1.4 in), distributed over 6 days.
The day lasts on average 15 hours and 20 minutes. So the days are long.
The average humidity is 72%. Hence, the air is normally humid.
The average wind speed is 10 kph (6 mph).

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In August, the weather in Aosta is usually warm. However, there are remarkable differences between night and day. The average temperature is of 21.5 °C (71 °F), with a minimum of 14.9 °C (58.8 °F) and a maximum of 28.1 °C (82.6 °F).
On the coldest nights of the month, the temperature usually drops to around 9.5 °C (49.5 °F). However, it dropped to 3.6 °C (38.5 °F) in August 2006.
On the warmest days of the month, the temperature usually reaches around 33.5 °C (92.5 °F). However, it reached 38 °C (100.4 °F) in August 2020.
Precipitation amounts to 40 mm (1.6 in), distributed over 7 days.
The day lasts on average 14 hours and 0 minutes.
The average humidity is 74%. Hence, the air is normally humid.
The average wind speed is 9 kph (6 mph).

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In September, the weather in Aosta is usually very mild. The average temperature is of 17.4 °C (63 °F), with a minimum of 11.7 °C (53.1 °F) and a maximum of 23.1 °C (73.6 °F).
On the coldest nights, which normally occur at the end of the month, the temperature usually drops to around 4.5 °C (40.5 °F). However, it dropped to -0.5 °C (31.1 °F) in September 2010.
On the warmest days, which normally occur at the beginning of the month, the temperature usually reaches around 29 °C (84.5 °F). However, it reached 34 °C (93.2 °F) in September 2019.
Precipitation amounts to 45 mm (1.8 in), distributed over 5 days.
The day lasts on average 12 hours and 30 minutes.
The average humidity is 76%. Hence, the air is normally humid.
The average wind speed is 10 kph (6 mph).

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In October, the weather in Aosta is usually mild. The average temperature is of 12.2 °C (54 °F), with a minimum of 6.8 °C (44.2 °F) and a maximum of 17.6 °C (63.7 °F).
On the coldest nights, which normally occur at the end of the month, the temperature usually drops to around 0.5 °C (33.5 °F). However, it dropped to -6.3 °C (20.7 °F) in October 2007.
On the warmest days, which normally occur at the beginning of the month, the temperature usually reaches around 24 °C (75 °F). However, it reached 30.7 °C (87.3 °F) in October 1997.
Precipitation amounts to 55 mm (2.2 in), distributed over 6 days.
The day lasts on average 10 hours and 55 minutes.
The average humidity is 77%. Hence, the air is normally humid.
The average wind speed is 11 kph (7 mph).

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In November, the weather in Aosta is usually quite cold. The average temperature is of 6.4 °C (44 °F), with a minimum of 1.4 °C (34.5 °F) and a maximum of 11.5 °C (52.7 °F).
On the coldest nights, which normally occur at the end of the month, the temperature usually drops to around -4.5 °C (24 °F). However, it dropped to -14.1 °C (6.6 °F) in November 2008.
On the warmest days, which normally occur at the beginning of the month, the temperature usually reaches around 20 °C (67.5 °F). However, it reached 23 °C (73.4 °F) in November 2015.
Precipitation amounts to 75 mm (3 in), distributed over 7 days.
The day lasts on average 9 hours and 25 minutes.
The average humidity is 74%. Hence, the air is normally humid.
The average wind speed is 13 kph (8 mph).

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In December, the coldest month of the year, the weather in Aosta is usually cold. The average temperature is of 0.8 °C (34 °F), with a minimum of -3.4 °C (25.9 °F) and a maximum of 5.1 °C (41.2 °F).
On the coldest nights of the month, the temperature usually drops to around -8 °C (17.5 °F). However, it dropped to -18.9 °C (-2 °F) in December 2010.
On the warmest days of the month, the temperature usually reaches around 17 °C (62 °F). However, it reached 21.7 °C (71.1 °F) in December 1994.
Precipitation amounts to 45 mm (1.8 in), distributed over 6 days.
The day lasts on average 8 hours and 40 minutes. December 21, the winter solstice, is the shortest day of the year in the Northern Hemisphere.
The average humidity is 70%.
The average wind speed is 14 kph (9 mph).