If you’re planning a summer trip to Oslo, get ready for mild, comfortable weather that makes wandering the city and exploring the fjords a real treat.
Average summer temperatures in Oslo usually run from the low 50s °F at night up to the upper 60s °F during the day, with July often topping the charts as the warmest month.
This combination of cool evenings and pleasant daytime highs gives you a great backdrop for both outdoor adventures and city sightseeing.
You’ll notice a mix of sunshine and cloudy skies, and daylight sticks around much longer than in most other European cities.
Rain shows up pretty often but usually stays light, so if you pack a light jacket or an umbrella, you’ll be set for those quick showers that don’t really mess up your plans.
Long days, moderate temps, and manageable rainfall make hiking, waterfront strolls, or hanging out in Oslo’s parks and museums really appealing.
If you get a sense of the seasonal climate, you’ll know what to pack and what to expect, so you can make the most of your time outside.
Overview of Oslo’s Summer Climate
Oslo’s summer months bring mild to warm temperatures, long daylight hours, and rainfall that’s frequent but not overwhelming.
You’ll get comfortable weather for outdoor activities, and the occasional shower keeps everything green.
Humid Continental Climate in Oslo
Oslo has a humid continental climate (Dfb), which means there’s no true dry season, and summers feel warm but not hot.
This climate comes from Oslo’s spot in southern Norway, close to the Oslofjord, and the Gulf Stream’s influence.
During summer, average daytime highs usually hit between 18°C and 22°C (64°F to 72°F).
Nights cool down, often landing between 10°C and 14°C (50°F to 57°F).
These moderate temperatures make walking, cycling, and sightseeing in the city easy and pleasant.
Rain falls year-round, and summer doesn’t really take a break.
You’ll see 65–90 mm (2.5–3.5 in) of rain per month in June, July, and August.
Showers tend to be brief, so they don’t usually cancel your plans for long.
Daylight really stands out in Oslo’s summer.
In June, you can get nearly 19 hours of daylight, so you have loads of time to be outside.
This long stretch of light is one of the things that makes southern Norway’s summers feel special.
Seasonal Weather Patterns
Summer weather in Oslo stays pretty steady, but you never know exactly what you’ll get.
Temperatures remain mild, but cloud cover and rainfall can change from week to week.
On average, skies stay partly cloudy about half the time.
July usually brings the warmest days, with highs around 21°C (70°F).
The Oslofjord’s sea temperatures reach 17–18°C (63–64°F), which is chilly but still fine for swimming if you’re up for it.
Locals often jump in, go kayaking, or take boats out on the water.
Rain peaks in August, making it the wettest summer month.
Even with the rain, sunshine hours stay high, averaging 7–8 hours per day.
This mix of sun and showers keeps Oslo’s parks and forests looking lush and green.
Wind doesn’t usually get too wild—speeds are light to moderate, so things feel calm compared to coastal Norway.
That makes outdoor dining, festivals, and hanging out by the water a lot more enjoyable in summer.
Comparison to Other Seasons
Summer in Oslo really stands out from the rest of the year.
Winters are long, dark, and cold, with average lows dropping below -6°C (21°F) and daylight getting as short as six hours.
In summer, you get warmth, long days, and a city that feels alive.
Spring is more of a transition, with temperatures climbing from near freezing in March to around 15°C (59°F) by May.
Days get longer in spring, but you don’t get the same steady warmth or outdoor buzz as you do in summer.
Autumn cools off fast, with temps falling from 15°C (59°F) in September to near freezing by November.
Rain picks up, and daylight hours shrink quickly, so being outside doesn’t feel as inviting.
If you want to see Oslo at its best, summer gives you the best mix of good temperatures, long light, and lots of chances for outdoor fun.
Typical Summer Temperatures in Oslo
Oslo’s summer brings mild to warm weather, with July usually coming in as the hottest month.
Temperatures shift between early and late summer, and you’ll notice a clear difference between the warmth of the day and the cooler nights.
Average Highs and Lows by Month
From June to August, Oslo enjoys steady, moderate warmth.
In June, average highs reach about 21 °C (70 °F), while lows dip to around 11 °C (52 °F).
July tops out with highs near 23 °C (73 °F) and lows close to 14 °C (57 °F).
By August, highs drop back to 21 °C (70 °F) and lows settle near 12 °C (54 °F).
These temperatures are great for outdoor activities without any extreme heat.
You won’t face the oppressive conditions you might find further south in Europe.
Instead, you get long days and warmth that’s easy to live with.
| Month | Avg High | Avg Low |
|---|---|---|
| June | 21 °C / 70 °F | 11 °C / 52 °F |
| July | 23 °C / 73 °F | 14 °C / 57 °F |
| August | 21 °C / 70 °F | 12 °C / 54 °F |
Temperature Fluctuations and Extremes
Temperatures can swing a bit from the averages.
Occasional warm spells push daytime highs above 25 °C (77 °F), but it’s rare to see anything much hotter.
Cloudy or rainy days can keep highs closer to 17 °C (63 °F).
Nights in mid-summer rarely fall below 10 °C (50 °F), but early June and late August can feel a bit chillier.
Oslo doesn’t really get hit with extreme summer heat, but the city’s inland fjord setting can trap some extra warmth on still days, making it a bit warmer than nearby coastal spots.
If you’re traveling, be ready for a range of conditions.
A light jacket works for evenings, and lighter clothes are good for daytime.
Daytime vs Nighttime Conditions
Daytime in Oslo’s summer feels comfortable and often sunny, with plenty of light.
Highs in the low 20s Celsius mean you can eat outside, hike, or sightsee without sweating it out.
At night, temperatures drop but stay mild.
Lows between 11–14 °C (52–57 °F) make for a noticeable change from the day.
Sleeping is usually comfortable, and most homes don’t even bother with air conditioning.
The switch from day to night happens gradually because of all the daylight.
In June, twilight lingers late, so the air cools down slowly.
By August, nights get darker and cooler, hinting that autumn isn’t far off.
Rainfall and Precipitation Trends
Summer in Oslo brings a moderate amount of rain, steady daylight, and mild temps.
You’ll see precipitation spread out over the season, with some differences in how much rain falls and how often.
Monthly Rainfall Totals
Rain in Oslo during summer is moderate compared to other parts of Norway.
June and July usually get between 70–90 mm of rain each month.
August is the wettest summer month, averaging around 110–115 mm.
Most rain comes as showers, not long storms.
You’ll often notice a quick downpour, then clearer skies.
| Month | Average Rainfall (mm) |
|---|---|
| June | 75–85 mm |
| July | 80–90 mm |
| August | 110–115 mm |
These totals aren’t extreme, but they’re enough that you’ll want to bring a light rain jacket or umbrella.
Frequency of Rainy Days
The number of rainy days matters as much as the total rainfall.
On average, expect 12–16 days with measurable precipitation per month in summer.
August usually has the most, with about 16 days of rain.
Rainy days don’t usually mean all-day downpours.
Most often, you’ll get a few hours of showers, often in the afternoon or evening.
That means you can still enjoy the outdoors in the morning before the weather shifts.
Since rainy days are pretty common, it’s smart to keep your plans flexible.
Museums, indoor markets, and cultural spots are good backups when the skies turn gray.
Humidity Levels in Summer
Humidity in Oslo during summer stays moderate and pretty comfortable.
Relative humidity usually falls between 65% and 75%.
Cooler evenings help keep the air feeling fresh, even after a rainy day.
You might notice a bit of stickiness on warmer afternoons, especially in July, but it rarely gets uncomfortable compared to more humid places.
The mix of moderate humidity and regular showers keeps Oslo’s parks, forests, and fjord areas green and inviting.
That’s a big reason why spending time outdoors feels so good, even if it rains now and then.
Sunshine and Daylight Hours
Oslo’s summer gives you long days with loads of daylight and a decent dose of sunshine.
You’ll find plenty of chances to enjoy being outside, but sunshine hours can shift depending on the month and weather.
Average Daily Sunshine
During summer, you can expect 6 to 8 hours of direct sunshine per day on average.
May and June usually bring the brightest days, hitting the top of that range.
July still gives you strong sunshine, but you’ll probably see a bit more cloud cover than in June.
Remember, sunshine hours aren’t the same as daylight hours.
Oslo gets long days, but not all of it is sunny—clouds and rain, especially in July and August, can cut down the hours when the sun is out.
If you’re planning outdoor adventures, June usually offers the best mix of long days and steady sunshine.
August stays pleasant, but with more rain, you’ll see fewer clear skies.
Longest Days of the Year
Because of Oslo’s northern spot, you get very long days in summer.
Around late June, near the summer solstice, daylight can last about 18–19 hours per day.
Even in late May and early July, you’ll see over 17 hours of daylight.
This stretch of light gives the city a unique vibe.
The sun sets late, and twilight hangs around for ages, so nights feel super short.
You won’t really see full darkness during midsummer, just a dim twilight around midnight.
By late August, daylight drops to about 14 hours, but evenings still feel bright compared to most other European cities.
That long daylight is a big draw for visitors in Oslo’s summer.
UV Index During Summer
The UV index in Oslo during summer usually sits between 5 and 7 on clear days.
That’s strong enough to cause sunburn if you’re outside for a while without protection.
You’ll want to use sunscreen, sunglasses, and some protective clothing, especially if you’re hanging out near the water where the sunlight bounces back at you.
The midday hours from 11 a.m. to 3 p.m. bring the highest UV exposure.
Clouds can lower the UV index, but they don’t take away the risk.
Even on partly cloudy days, UV rays get through and can affect your skin.
A few simple precautions help you enjoy Oslo’s summer weather without worry.
Wind and Atmospheric Conditions
Oslo’s summer brings light to moderate winds and steady air pressure.
These conditions make it comfortable to spend time outside, but you still get reminders you’re in the north with some variation.
Typical Wind Speeds
Average summer wind speeds in Oslo stay low, around 4 mph.
The city feels calm, especially compared to Norway’s coast where winds pick up more often.
Winds are most noticeable in late spring and early autumn, with speeds closer to 9 mph in May and September.
During June, July, and August, the lighter winds help keep summer weather steady and mild.
Oslo’s geography matters too.
The Oslofjord and nearby hills block a lot of wind in the city center.
You might notice a little more breeze along the waterfront, but most inland areas stay pretty sheltered.
If you’re visiting, you won’t need to worry about strong winds messing up your plans.
Light breezes happen, but disruptive gusts are rare.
Air Pressure and Stability
Air pressure in Oslo during the summer usually sits around 740 mmHg. This steady value keeps weather patterns stable, so you don’t get those wild swings like in winter or spring.
The Gulf Stream helps out a lot here, keeping the atmosphere pretty mild and stopping any big jumps in pressure. Because of that, you’ll notice conditions change gradually—sunny one day, maybe a bit cloudier the next, but not much drama.
Stable pressure means severe weather rarely shows up. Sure, you might get some rain now and then, especially in August, but it’s usually just light or moderate showers.
If you’re visiting, you’ll probably appreciate these predictable patterns. Whether you’re walking along Karl Johans gate or hiking by the fjord, the air stays consistent and easy to get used to.
Sea Temperatures and Outdoor Activities
Oslo’s summer air feels mild, but the sea stays much colder than you might hope. The water temperature really shapes which outdoor activities feel comfortable or even possible.
Average Sea Temperatures
The Oslofjord warms up slowly through spring and finally peaks in mid to late summer. In June, the sea temperature averages about 9°C to 15°C (48°F to 59°F), which most people find way too chilly for long swims.
By July, the water gets a bit warmer, reaching around 11°C to 18°C (52°F to 65°F), so that’s about as good as it gets for the year.
August keeps things similar, with averages between 12°C and 18.5°C (54°F to 65°F). It’s still pretty cool by international standards, but if you’re set on water activities in Oslo, this is the best window.
For comparison:
- June: Swimming feels cold
- July–August: Cool, but short swims are doable
- September: Drops again to about 10°C to 16°C (50°F to 61°F), so it gets uncomfortable fast
People usually wear wetsuits for longer sessions in the water, especially if they’re kayaking, paddleboarding, or swimming out in the open.
Best Months for Water Activities
If you’re looking to enjoy water activities in Oslo, July and August really stand out. The sea feels warmer, and air temperatures usually hit 20°C to 22°C (68°F to 72°F), so jumping into the chilly water doesn’t seem quite as crazy.
During these months, you can try kayaking, sailing, paddleboarding, or short swims along the Oslofjord. Locals flock to beaches like Huk and Paradisbukta for sunbathing and those quick, refreshing dips.
June and September don’t work as well for swimming, but they’re still pretty good for boating or kayaking. With the right gear, you’ll still have a good time on the fjord, though the colder water makes things less comfortable for casual swimmers.
If you want to swim without a wetsuit, it’s smart to keep your time in the water short, especially if you’re outside of July and August.