Weather in Groningen in January

The month to avoid. January is the month most people should skip in Groningen. Highs sit at 4.3 °C and the day is short; this is an indoors-with-excursions month, not an outdoors-all-day one.

January ranks 12 of 12 — near the bottom of Groningen's year. June is the month that works, and the swing between the two is 55 points, which is a different holiday rather than a slightly better one.

This is persistent light rain rather than storms: 16 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 4.3 °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: 14 nights fall below freezing; the day barely swings — 4.5 °C between the overnight low and the afternoon high. Across the twenty years measured, the hottest January day reached 12.8 °C and the coldest night fell to -16.3 °C, and the wettest single day dropped 30 mm — roughly 39% 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 132 mm against 25 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 16.4 km/h — a steady breeze rather than a nuisance, and welcome on the warmer days, and humidity runs at 93%, which at 4.3 °C means damp rather than muggy — the kind of cold that gets into a coat and stays there.

How January sits in the year

This is a turning point in the year — December and February sit on opposite sides of it, so the month contains the change rather than following it.

Daylight in January

January sits at the dark end of Groningen's year — 8 hours of daylight against 16.9 at midsummer, gaining 1.2 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 6.3 °C in January — too cold to swim without a wetsuit. The sea peaks at 18.4 °C in August and bottoms out at 5.3 °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 Groningen versus nearby

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

So: January is a compromise. June is 55 points better and is what Groningen 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 Groningen

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