Weather in Reykjavík in December

The month to avoid. Of the twelve, December is the one to avoid. Highs sit at 2.4 °C and the day is short; this is an indoors-with-excursions month, not an outdoors-all-day one.

December ranks 12 of 12 — near the bottom of Reykjavík's year. July is the month that works, and the swing between the two is 38 points, which is a different holiday rather than a slightly better one.

Rain on 21 of the month's 31 days, 5 of them heavy. At that frequency a wet-weather backup is not a contingency, it is the itinerary — book the indoor things first and treat the clear days as the bonus. Layers, and a genuinely waterproof outer — at 2.4 °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: 18 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 December day reached 9.9 °C and the coldest night fell to -11.6 °C, and the wettest single day dropped 55 mm — roughly 32% of the month's rain in one day.

December is statistically steady but not small: the year-to-year variation is modest in relative terms, yet the wettest December on record still delivered 283 mm against 91 mm in the driest. In a month this wet, even a tame spread is a lot of rain in absolute terms — the 172 mm average is a reasonable planning figure, not a promise.

Wind sits around 16.5 km/h — a steady breeze rather than a nuisance, and welcome on the warmer days, and humidity runs at 92%, which at 2.4 °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: 3.7 °C in November, 2.4 here, 2.1 in January. Nothing about the timing within the month matters much.

Daylight in December

December sits at the dark end of Reykjavík's year — 4.3 hours of daylight against 21 at midsummer, losing 0.9 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 7.9 °C in December — too cold to swim without a wetsuit. The sea peaks at 12 °C in August and bottoms out at 7.3 °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.

December in Reykjavík versus nearby

If Reykjavík is one option among several, the nearby comparison is worth making. Akureyri is the weaker option in December — 6.3 °C cooler, the same number of rain days. Glasgow is close enough to be a coin toss — 3.8 °C warmer, 1 day less rain.

So: December is a compromise. July is 38 points better and is what Reykjavík 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 Reykjavík

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