Lake Maggiore, where it's located

On Lake Maggiore, situated at 200 meters (650 feet) above sea level, the climate is temperate, with cold, damp winters and warm summers, which are characterized by a good amount of sunshine but also by quite frequent thunderstorms. Because of both the influence of the lake and the location at the foot of the Alps, the climate of Lake Maggiore is a bit milder and much more rainy than in the Po Valley.
The lake is divided between the provinces of Verbano-Cusio-Ossola and Novara in Piedmont (on the western side), and Varese in Lombardy (on the eastern side), while the northern part belongs to Switzerland, in the Canton of Ticino.
Within the lake, some small islands are found, such as the Borromean Islands (among which we can mention Isola Madre and Isola Bella), between Stresa and Verbania, and the Brissago Islands on the Swiss side.
Here is a list of some towns situated on the shores of the lake. In Piedmont: Cannobio, Cannero Riviera, Oggebbio, Ghiffa, Verbania, Baveno, Stresa, Belgirate, Lesa, Meina, Arona, Dormelletto, Castelletto sopra Ticino. In Lombardy: Sesto Calende, Angera, Ranco, Ispra, Brebbia, Besozzo, Monvalle, Leggiuno, Laveno-Mombello, Castelveccana, Porto Valtravaglia, Brezzo di Bedero, Germignaga, Luino, Maccagno, Tronzano Lago Maggiore, Pino sulla Sponda del Lago Maggiore. In Ticino: Ranzo, Gerra, San Nazzaro, Vira, Magadino, Tenero, Locarno, Ascona, Ronco sopra Ascona, Brissago, Minusio, Muralto.
Here are the average temperatures of Verbania, on the western shore of the lake (whose municipality is in turn divided into the villages of Intra and Pallanza). The averages cover the period 1961/90, when the climate was slightly colder than today.
Verbania - Average temperatures
Min (°C)01471115171714941
Max (°C)681216202427262217117
Min (°F)323439455259636357483934
Max (°F)434654616875817972635245

Rainfall in Verbania is abundant, since it amounts to 1,565 millimeters (61.5 inches) per year: that of Lake Maggiore is one of the wettest areas of Italy. In Locarno, in the Swiss side, precipitation reaches as high as 1,900 mm (75 in) per year. Winter is the relatively driest season. In spring and autumn, when Atlantic depressions pass over the area, the rains are abundant because the southern currents are forced to climb the Alpine foothills. In late spring and summer, thunderstorms are quite frequent (and sometimes intense) in the afternoon and evening.
During the most intense waves of bad weather, which occur in autumn (but sometimes also in spring), the lake may overflow, flooding the coastal towns.
Here is the average rainfall in Verbania.
Verbania - Average precipitation

In the cold half of the year, the wind on Lake Maggiore is often weak or non-existent, except when the favonio (or föhn) blows, the warm and dry wind that comes down from the Alps and is able to bring clear skies and very good visibility. During the warm half of the year, under conditions of good weather, the wind is weak or moderate and follows the breeze regime (and it is more intense in late spring than in midsummer): during the warmest hours, it blows from the plains to the mountains (the breeze from the south, called "inverna"), while after sunset and at night, it blows from the mountains to the plains (the "tramontana", the breeze from the north). The breeze is appreciated by lovers of sailing, surfing and windsurfing.

On the shores of Lake Maggiore, winter, from December to February, is pretty cold, but it's not as cold as in the Po valley because of the mitigating influence of the lake. Fog is less frequent as well.
There is a moderate amount of rainy days, though this is the driest season. Snow is definitely more rare on the lake than in the surrounding hills, however, it usually falls at least once every year, and can sometimes be abundant, especially on the northern side: in Verbania, snowfall amounts to about 20 centimeters (8 in) per year, while in Locarno, in the north, it exceeds 50 cm (20 in) per year. However, snow tends to melt soon enough. We can not exclude very cold periods, with night frosts, and temperatures around freezing or even below even during the day.

Summer, from June to August, is warm, and often sunny in the morning. The heat is less intense than in the Po Valley, in addition, there is more wind because of the lake breeze. Sometimes, an Atlantic front, able to bring some cool and rainy days, can affect this area; more often, thunderstorms can break out in the afternoon and evening. We can not exclude some particularly hot days, with highs around 35 °C (95 °F).
During summer, the water temperature in Lake Maggiore reaches 20/22 °C (68/70 °F), so it remains cool, except in periods of intense heat, when it can reach higher values; it also varies depending on the proximity to rivers and streams that feed it (there are several tributaries, including the Toce and Tresa Rivers, and only one emissary, the Ticino River, in the south, near Sesto Calende).

Isola dei Pescatori and Isola Madre from Stresa

The amount of sunshine on lake Maggiore is acceptable in winter, when there are sunny days alternating with cloudy periods (in January, there are 4 hours of sunshine per day, like in Rome). In the other seasons, however, it is not that high because Atlantic disturbances pass quite frequently in spring and autumn, while in summer, in periods of good weather, cloudiness can form in the afternoon, which can then lead to thunderstorms. In July, the sunniest month, there are only 8 hours of sunshine per day on average (compared for example to the 9 hours of Milan and the 9.5 hours of Bologna, not to mention the 11 hours of Rome).
Verbania - Sunshine

Near Lake Maggiore, there are a few smaller lakes, where the climate is similar. To the west, we find Lake Orta, about ten kilometers (18 miles) away and at 300 meters (1,000 feet) above sea level, and Lake Mergozzo (which was once linked to Lake Maggiore and is now separated by the Fondotoce plain). To the east, we find the lakes of Monate, Comabbio and Varese, at an altitude of around 250 meters (800 ft). In the north-east, we find Lake Lugano, 270 meters (885 feet) above sea level, most of which is located in Switzerland.

Best Time

The best times to visit Lake Maggiore are spring and early summer, in particular, from mid-April to mid-June. September, too, is a good month. However, you have to take into account some rainy days in both periods.
Summer, which is the best time for a beach holiday, can sometimes be too hot to visit the towns and to go on excursions, though there are many days with acceptable temperatures, especially in June. In summer and in May, afternoon or evening thunderstorms are to be taken into account.