SEASONS: Venice has a four-season year. Spring (March and April) is the season of vegetative regrowth, while periods of cool and cloudy weather alternate with spells of warm and sunny days. Summer (May through September) brings long days, lush growth, and warm weather. Autumn (October and November) sees the days shorten, the rains increase, and the first frosts appear. Winter is the season of short, cloudy, foggy, and cold weather
--punctuated by short spells of mild temperatures and sunny skies.
SUNNIEST MONTHS: Late June through the middle of September. This is when you can expect to get the sunniest weather of the year and the most clear days. For the year as a whole, 54% of the daylight hours will be sunny--from a high of 72% in August, to a low of 44% in December. Note that even the winter months get almost half of the available sunshine.
During the cooler months, morning fogs and mists make the afternoons the sunniest time of day. During the summer, just the opposite is true. The mornings are clear and sunny, while the afternoons build cumulus clouds that often lead to thundershowers.
WARMEST MONTHS: The same season as the sunniest ones; that is, late June through the middle of September. During this time, the afternoons are warm to hot--rarely very hot. Nights stay mild to warm, rarely cool. The hottest temperature of the year will be around 90░, and will probably occur in either July or August.
From late May through the end of September, most nights will be hot enough that you will sleep better with some sort of room-cooling.
COOLEST MONTHS: Late November through the first few days in March. At this time of year, you can expect frosty mornings two or three days a week. Three or four times a winter, Arctic air moves over the Alps and down into Venice, keeping the afternoon temperatures below freezing all day. The coldest temperature of the year will be around 22░, and will probably occur during one of these January cold snaps.
Snow flurries occur on and off during the winter months, but the waters of the lagoon keep the piazzas too warm (and too wet) for any accumulation. They have frozen, but not in living memory.
DRIEST MONTHS: Midwinter and midsummer. Some 73% of the year's days will get no measurable precipitation; that is, they will get less than a hundredth of an inch. January and August will have 80% such days, whereas May will get only 63%. A "dry day" in the table, however, is one with less than a tenth of an inch--a more useful measure. It takes at least that much to wet the ground under the trees.
THINGS TO KNOW: Sea temperatures are for the waters of the Adriatic, off the Lido. The waters of the lagoon are warmer, but are heavily polluted (as are all of the city's canals--as your nose will tell you).
During the cooler months, the prevailing winds are largely from the north and west, down the valley of the Po River. During the warmer ones, they reverse and blow off the Adriatic and up the valley. This brings a welcome coolness and change of air to the city.
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