Map from Google - Como

In Como, and other locations around the lake of the same name such as Cernobbio and Bellagio, located at 200 metres (650 feet) above sea level, the climate is semi-continental, with cold, damp winters and hot summers, fairly sunny but also accompanied by quite frequent thunderstorms. Because of the influence of the lake, the climate of Como is a bit milder and rainier than in the Po Valley.
In the cold half of the year, the wind is generally weak or absent, except when the föhn blows, the warm, 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, in the area of Lake Como, the wind is weak or moderate and follows the breeze regime (which is more intense in late spring than in midsummer): during the warmest hours, the breeze blows from the plains towards the mountains (the "Breva", generally from the south), while after sunset and at night the breeze blows from the mountains to the plains (the "Tivano", generally from the north).
The average temperature of January is 4 °C (39 °F), that of July is 23.5 °C (74.5 °F). Here are the average temperatures.
Average temperatures - Como
ComoJanFebMarAprMayJunJulAugSepOctNovDec
ComoJFMAMJJASOND
Min (°C)125812161818141052
Max (°C)791317212629272418128
Min (°F)343641465461646457504136
Max (°F)454855637079848175645446

The rains are plentiful, given that they amount to 1,300 millimetres (51 inches) per year, so that Como is one of the rainiest cities in Italy. Winter is the relatively drier season; the rains are abundant in the intermediate seasons, when Atlantic depressions pass, due to high altitude southern currents which then climb the Alpine foothills, while in late spring and summer, thunderstorms in the afternoon or in the evening are quite frequent (and sometimes intense). During the most intense waves of bad weather, which occur in autumn (but sometimes also in spring), the lake's water may overflow, flooding the lower areas of the city.
Here is the average precipitation.
Average precipitation - Como
ComoJanFebMarAprMayJunJulAugSepOctNovDecYear
ComoJFMAMJJASONDY
Prec. (mm)707511510516013585135115125130651320
Prec. (in)2.834.54.16.35.33.35.34.54.95.12.652
Days6689121079778695

Winter, from December to February, is pretty cold, but less than in the Po valley, because of the warming influence of the lake. Even fog is less frequent.
There's no shortage of rainy days, although winter is the relatively driest season. Snow generally falls at least once every year, and sometimes may be abundant, but tends to melt soon enough. We can not exclude very cold periods, with night frosts and temperatures around 0 °C (32 °F) or below, even during the day.

Summer, from June to August, is hot, and often sunny in the morning. The heat is less intense than in the Po Valley, in addition there's a little more wind because of the lake breezes. Sometimes an Atlantic front, able to bring some cool and rainy days, can pass; 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 the summer, the temperature of Lake Como reaches 17/19 °C (63/66 °F), except in periods of great heat, in which it can reach higher values; in addition it varies varies depending on the proximity of the rivers and streams that feed it; it is typically slightly higher in the western branch than in the eastern branch (Lake Lecco), because in the latter the waters flow more quickly (since there is an emissary, the Adda River, from which the waters flow out).

The amount of sunshine in Como is quite scarce in winter, when the sun is seen quite rarely; in other seasons, however, it is not so high, at least compared to other parts of Italy, because in spring and autumn Atlantic disturbances pass quite frequently, while in periods of good summer weather, cloudiness in the afternoon can form, which can lead to thunderstorms: in July, the sunniest month, there are only 7.5 hours of sunshine per day on average (compared for example to 9 hours in Milan and 9.5 in Bologna).

Como

In the mountainous areas around the lake, the climate gets colder with altitude, as you can see from the average temperatures of Mount Bisbino, at 1,300 metres (4,250 feet) above sea level. In winter you may encounter heavy snowfalls, while in summer there are frequent afternoon cloudiness, often resulting in thunderstorms.
Average temperatures - Monte Bisbino
Monte BisbinoJanFebMarAprMayJunJulAugSepOctNovDec
Monte BisbinoJFMAMJJASOND
Min (°C)-3-3-1261012121061-2
Max (°C)235913172019161263
Min (°F)272730364350545450433428
Max (°F)363741485563686661544337


The best times to visit Como are spring and early summer, in particular from mid-April to mid-June. Also September is a good month. You should however take into account some rainy days in both periods.
In summer, temperatures can be hot, although many days are acceptable, especially in June. We must take into account, in summer and in May, afternoon or evening thunderstorms.