Weather in Rotterdam in January

The month to avoid. Of the twelve, January is the one to avoid. Highs sit at 5.6 °C and the day is short; this is an indoors-with-excursions month, not an outdoors-all-day one.

January ranks 11 of 12 — near the bottom of Rotterdam's year. June is the month that works, and the swing between the two is 47 points, which is a different holiday rather than a slightly better one.

This is persistent light rain rather than storms: 15 wet days but only 1 heavy ones. It rarely cancels anything outright, and it rarely fully clears either. A jacket beats an umbrella. Layers, and a genuinely waterproof outer — at 5.6 °C the difference between a good day and a miserable one is entirely down to what you are wearing.

What the averages hide

Averages flatten a month, and this one hides a few things: 8 nights fall below freezing; the day barely swings — 3.5 °C between the overnight low and the afternoon high. Across the twenty years measured, the hottest January day reached 12.5 °C and the coldest night fell to -8.1 °C, and the wettest single day dropped 26 mm — roughly 34% of the month's rain in one day.

January is statistically steady but not small: the year-to-year variation is modest in relative terms, yet the wettest January on record still delivered 128 mm against 20 mm in the driest. In a month this wet, even a tame spread is a lot of rain in absolute terms — the 77 mm average is a reasonable planning figure, not a promise.

Wind sits around 18.5 km/h — a steady breeze rather than a nuisance, and welcome on the warmer days, and humidity runs at 91%, which at 5.6 °C means damp rather than muggy — the kind of cold that gets into a coat and stays there.

How January sits in the year

Temperatures hold steady either side: 6.6 °C in December, 5.6 here, 6 in February. Nothing about the timing within the month matters much.

Daylight in January

January sits at the dark end of Rotterdam's year — 8.2 hours of daylight against 16.7 at midsummer, gaining 1.1 hours across the month. Sightseeing days are genuinely shorter, and an itinerary built for summer will not fit.

Sea temperature

The sea sits at about 7.6 °C in January — too cold to swim without a wetsuit. The sea peaks at 17.7 °C in August and bottoms out at 6.4 °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

Off season. The genuine off season: cheapest by a distance, with the caveat that some tours and restaurants close entirely.

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

January in Rotterdam versus nearby

If Rotterdam is one option among several, the nearby comparison is worth making. Breda is close enough to be a coin toss — within a degree on temperature, the same number of rain days. Lille is close enough to be a coin toss — within a degree on temperature, 1 day less rain.

So: January is a compromise. June is 47 points better and is what Rotterdam 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 Rotterdam

See all twelve months in Rotterdam, or where else to go in January.