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 0.5 °C (33 °F), that of the warmest month (July) is of 21.5 °C (71 °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.