Weather in Reykjavík in May

A hard month. May asks something of you. Go in knowing what. Highs sit at 8.5 °C and the day is short; this is an indoors-with-excursions month, not an outdoors-all-day one.

May ranks 4 of 12 in Reykjavík: past the worst of the year but short of July, which is the month to book if the dates are open.

Rain on 15 days, 3 of them heavy. Enough to need a plan B, not enough to need a plan around it. Layers, and a genuinely waterproof outer — at 8.5 °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: 3 nights fall below freezing; the day barely swings — 4.8 °C between the overnight low and the afternoon high. Across the twenty years measured, the hottest May day reached 16.9 °C and the coldest night fell to -3.6 °C, and the wettest single day dropped 30 mm — roughly 32% of the month's rain in one day.

May is statistically steady but not small: the year-to-year variation is modest in relative terms, yet the wettest May on record still delivered 194 mm against 26 mm in the driest. In a month this wet, even a tame spread is a lot of rain in absolute terms — the 93 mm average is a reasonable planning figure, not a promise.

Wind is light at 10.7 km/h, so the temperature on the page is close to the temperature on your skin, and humidity runs at 83%, which at 8.5 °C means damp rather than muggy — the kind of cold that gets into a coat and stays there.

How May sits in the year

The month is on the way up: 3 °C warmer than April, and June adds another 3.6 °C. Late in the month feels noticeably different from the start of it, which is worth knowing if the trip is short.

Daylight in May

18.3 hours of daylight, gaining 3.2 hours across the month. That is between Reykjavík's extremes of 21 and 4.3 hours, so days are long enough not to constrain the plan.

Sea temperature

The sea sits at about 8.2 °C in May — 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

Shoulder. The value months — prices ease off and you get the place closer to itself.

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

May in Reykjavík versus nearby

If Reykjavík is one option among several, the nearby comparison is worth making. Akureyri is the weaker option in May — 7.3 °C cooler, 3 days more rain. Glasgow is a better bet in May — 5.4 °C warmer, 3 days more rain.

So: May works, with July the better month by 16 points if the dates can move. If they cannot, nothing here should stop you booking.

Every month in Reykjavík

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