Oslo weather in May
May in Oslo: nice, a little rain, with clean air — an excellent time to visit.
Updated September 2026 · climate normals from ERA5 reanalysis
#4 of 12 months in Oslo · #610 of 1413 destinations to visit in May · comfort 83/100 (tier A)
- Days
- 18°C
- Nights
- 8°C
- Wet days
- 9
- Sun
- 11.8 h
- Humidity
- 67%
- Daylight
- 17 h

What May is like in Oslo
17 May, the national day, brings the entire city onto the street in traditional dress; blossom in the parks and light until late.
festivalblossom
confidence: high
Traveller notes on Oslo in May
Asked whether it can snow here in May, regulars say yes - they have seen everything from freezing and snowing to close to 30C in this month - and our row keeps 3.1cm in the snow column to prove the point. The averages are milder than that sounds: 18.2C by day reading as 16C, 7.7C nights that feel like 5C, and 58.9mm of rain across 9.1 days. What May reliably delivers is 17.2 hours of daylight with 11.8 of sun. The 17th is Constitution Day, when the parade starts at ten and the city becomes a street festival - the one date in the month worth planning around. The record: humidity 67 percent, a 14.2 kph wind and AQI 43.
Other months in Oslo
Regulars are specific that snow is essentially gone from the city and coast by this point, spring flowers already blooming downtown, while the surrounding mountains stay genuinely buried - a real split within a short train ride of each other. Our row backs that transitional, still-cool read, 12.2C over 2.5C nights feeling -1C, with 39mm of rain across 6.4 days and a trace of late-season snow, 9.6cm, reflecting those higher-elevation totals rather than anything falling downtown. Regulars are consistent the weather itself stays genuinely unpredictable day to day, capable of a sunny, mild afternoon or a grey, wet one with little warning either way. Layers that can be added or shed, plus a proper waterproof outer layer, remain the standard packing advice. The record: humidity 70 percent, 10 hours of sun, a 13.8 kph wind and AQI 39.
Regulars give August in Oslo as 20 to 25C by day, occasionally reaching 30C, and are careful to correct a common expectation: this city sits well outside the Arctic Circle, so there is no midnight sun - what there is, is light until about eleven in the evening. Our row reads 21.7C over 12.8C with 15.5 hours of daylight. They also say the second half of August differs little from the first and that everything is still open, while September turns cooler, wetter and noticeably darker. Rain is part of it here at 110.5mm across 11.6 days. The record: humidity 79 percent, 9.9 hours of sun, a 13.8 kph wind and AQI 35.
July in Oslo is warm by Norwegian standards rather than by anyone else's - regulars are careful that hot here does not mean what it means further south, and note that the Oslo area peaks in the first fortnight of August, which is also when the water is warmest. Our row gives 23.8C days, 14C nights and nearly 18 hours of daylight. The question they get asked most is whether the city empties, and the answer is half-yes: most Norwegians are on holiday in July and it is quieter than May, but students stay on to keep things running and the tourists more than fill the gap. The record: 10.5 precipitation days carrying 84mm, humidity 73 percent and 12 hours of sun.
Oslo forum threads describe January as typically hovering around 0C but posters were clear real cold snaps down to -15C are entirely possible, with the surrounding hills making local weather genuinely variable - grey and damp near zero one stretch, then a sharp drop toward -10 to -20C the next. Snow was described as almost a given in the city through January and February, and hills just outside town like Holmenkollen and Tryvann reliably hold even more. Posters flagged one specific hazard: a mild spell can turn existing snow to ice, making the city genuinely slippery, and recommended ice grips for shoes as real gear rather than an optional extra. Daylight runs to roughly 7 hours between sunrise and sunset, and free public ice-skating in the city center was mentioned as a solid way to spend a cold day.
Year-round notes are on Oslo's overview. Add your own note from Oslo's card on the map.
Oslo climate normals — May
Monthly averages from ERA5 reanalysis. AQI is the mean US Air Quality Index for the month.
Crowds in Oslo in May
How busy the place itself is — school and mass holidays, the months an editor tagged, and how sought-after the weather makes them. Never part of the comfort score.
BusyConstitution Day, 17 May, school holidays in 4 of the markets that fill it(estimated)
Peak crowdsBusyShoulder seasonQuiet
Best months for Oslo's weather
Ranked by this destination's own climate comfort score across the year — a different thing from how busy it gets (see Crowds above).
Fair weatherOslo's weather peaks June–August, best around July.
Best weatherFair weatherToughest weather
What's on in Oslo in May
Recurring seasonal events, natural spectacles, closures and holidays — curated and sourced.
- Festival
Constitution Day, 17 May
17 MayNational holidayCrowdedThe whole city walks in national dress, children's parades fill Karl Johans gate from breakfast, and nothing else happens all day. Restaurants book out weeks ahead. Source ↗
Where is Oslo?
Oslo in May — FAQ
- Is May a good time to visit Oslo?
- May in Oslo: nice, a little rain, with clean air — an excellent time to visit. It ranks #4 of 12 months for Oslo on SeasonMap's comfort score (83/100).
- What is the weather like in Oslo in May?
- In May, Oslo averages a daily high of 18.2°C and a low of 7.7°C, with about 58.9 mm of rain over roughly 9.1 rainy days.
- What is the air quality in Oslo in May?
- Oslo has a mean US Air Quality Index of about 43 in May.
- Does it snow in Oslo in May?
- Oslo sees roughly 3.1 cm of snowfall in May.