Weather in Aveiro in December

Shoulder season. December is shoulder season in Aveiro — cheaper, quieter, and a genuine gamble. Highs sit at 14.5 °C and the day is short; this is an indoors-with-excursions month, not an outdoors-all-day one.

December ranks 11 of 12 — near the bottom of Aveiro's year. July is the month that works, and the swing between the two is 43 points, which is a different holiday rather than a slightly better one.

Rain on 12 days, 4 of them heavy. Enough to need a plan B, not enough to need a plan around it. Layers, and a genuinely waterproof outer — at 14.5 °C the difference between a good day and a miserable one is entirely down to what you are wearing.

What the averages hide

The averages here are honest — no hidden extremes worth planning around. Across the twenty years measured, the hottest December day reached 19.2 °C and the coldest night fell to -0.4 °C, and the wettest single day dropped 59 mm — roughly 54% of the month's rain in one day.

December is moderately variable: 7 mm in the driest year against 263 mm in the wettest, around an average of 110 mm. Roughly two Decembers in three land near that average, and the third does something else entirely.

Wind is light at 6.6 km/h, so the temperature on the page is close to the temperature on your skin, and humidity runs at 85%, which at 14.5 °C means damp rather than muggy — the kind of cold that gets into a coat and stays there.

How December sits in the year

Temperatures hold steady either side: 16.9 °C in November, 14.5 here, 13.8 in January. Nothing about the timing within the month matters much.

Daylight in December

December sits at the dark end of Aveiro's year — 9.3 hours of daylight against 15.1 at midsummer, holding steady all month. Sightseeing days are genuinely shorter, and an itinerary built for summer will not fit.

Sea temperature

The sea sits at about 15.2 °C in December — cold — a quick dip rather than a swim, and a wetsuit if you are in for longer. The sea peaks at 18.5 °C in August and bottoms out at 13.7 °C — water lags the air by a month or two, which is why the best swimming often comes after the best weather.

How busy it gets

Quiet. Few other visitors, cheaper rooms, and a real chance some seasonal operators are shut.

Crowd levels are estimated from climate desirability and school-holiday calendars, not from visitor numbers.

December in Aveiro versus nearby

If Aveiro is one option among several, the nearby comparison is worth making. Leiria is close enough to be a coin toss — within a degree on temperature, 1 day less rain. Braga is close enough to be a coin toss — within a degree on temperature, 1 day more rain.

So: December is a compromise. July is 39 points better and is what Aveiro is actually like at its best — worth moving the trip for if that is possible, and worth adjusting expectations for if it is not.

Every month in Aveiro

See all twelve months in Aveiro, or where else to go in December.