Helsinki Weather by Month

Helsinki has a humid continental climate with significant seasonal variation, shaped by its position on the Baltic Sea at 60 degrees north latitude. Winters are cold and snowy, with temperatures routinely dropping to -7°C (19°F) and the Baltic Sea freezing along the shoreline. The city averages 132 days of precipitation annually and receives 1695 hours of sunshine per year. Summer days stretch past 18 hours of daylight in June and July, while December brings just 6 hours of weak winter sun. The Gulf Stream’s residual influence keeps Helsinki marginally warmer than other cities at this latitude like Anchorage or Magadan, but don’t expect anything mild: January and February in Helsinki are cold, dark, and snowy. Check our Helsinki best time to visit guide for more information.

Helsinki Weather by Month: Temperature and Rainfall Breakdown

Helsinki Weather in Winter (December to February)

Winter in Helsinki runs from December through February, with temperatures hovering between -8°C (18°F) and -2°C (28°F). Daytime highs struggle to reach 0°C (32°F) even in the warmest hours. Snow cover typically arrives in late November or early December and persists for 3 to 4 months, reaching depths of 20 to 40 cm in a normal winter. December is the darkest month: sunrise occurs around 09:15 and sunset around 15:15, giving just 6 hours of dim daylight. January is typically the coldest month with average lows of -7°C (19°F), though cold snaps from Siberia can push temperatures below -20°C (-4°F) for several days. The Baltic Sea freezes over in sheltered harbours, and icebreakers keep the main shipping channels open. February is marginally brighter, with 2.5 hours of daily sunshine and daylight extending to about 9 hours by month’s end. Snowfall averages 20 to 30 cm per month, and the city’s 300 km of cross-country ski trails are usually in excellent condition by February. Check our things to do in Helsinki for more information.

Helsinki Weather in Spring (March to May)

Spring arrives slowly in Helsinki. March is still firmly winter, with average highs of 2°C (36°F) and lows of -5°C (23°F). Snow begins melting in late March, and the city’s streets become slushy, so waterproof boots are essential. April brings the first real warmth, with daytime highs reaching 9°C (48°F) and sunlight extending to nearly 15 hours per day by month’s end. Trees begin budding and the first migratory birds return. May is a dramatic shift: temperatures jump to 16°C (61°F) highs and 5°C (41°F) lows, with 17 hours of daylight making the city feel alive. The last frost usually occurs by mid-May. This is when outdoor terraces open, and Helsinki’s cafe culture spills onto the streets. May is also the driest month on average, with just 35 mm of rainfall across 7 rainy days. Check our Helsinki events and festivals calendar for more information.

Helsinki Weather in Summer (June to August)

Summer is Helsinki’s finest season, with long daylight hours, mild temperatures, and the famous midnight sun effect. June averages 20°C (68°F) highs and 10°C (50°F) lows, with nearly 19 hours of daylight around the summer solstice on June 21. The sun sets around 22:50 and rises again at 3:50, and it never gets completely dark: there is astronomical twilight at best. July is the warmest month, with average highs of 22°C (72°F), though heatwaves can push temperatures to 28 to 30°C (82 to 86°F) for short periods. Rain is more frequent in July and August, with 61 mm and 75 mm respectively, often falling as short afternoon showers or thunderstorms. Sea temperatures peak at 17°C (63°F) in August, making a dip in the Baltic invigorating but brief. August sees the first signs of autumn, with daylight dropping to 15.5 hours by month’s end and nights cooling noticeably. Average summer humidity is a comfortable 65 to 75%. Check our Helsinki neighborhoods guide for more information.

Helsinki Weather in Autumn (September to November)

Autumn in Helsinki is cool, increasingly wet, and marked by rapidly shortening days. September is pleasant, with daytime highs of 15°C (59°F) and 13 hours of daylight at the start of the month, dropping to 11.5 hours by month’s end. The autumn foliage peaks in late September and early October, with brilliant yellows and reds in the city’s many parks and the surrounding forests. October brings a sharp cooldown: highs of 8°C (46°F), lows of 3°C (37°F), and the first frost typically arrives in the second or third week. October is also the wettest month on average, receiving 73 mm of rain across 11 rainy days. November is the least pleasant month in Helsinki: temperatures hover between -1°C (30°F) and 3°C (37°F), daylight shrinks to 7.5 hours, and the city receives only 1.1 hours of daily sunshine. Rain frequently mixes with sleet, and the first snowfall of winter usually arrives in late November. It’s a month of dark grey skies, biting wind off the Baltic, and a general damp chill that makes the cold feel worse than the thermometer suggests. Check our where to stay in Helsinki for more information.

Daylight Hours in Helsinki Throughout the Year

Helsinki’s extreme latitude creates one of the most dramatic daylight swings of any capital city. At the winter solstice (December 21), the sun is above the horizon for just 5 hours and 49 minutes. At the summer solstice (June 21), daylight lasts 18 hours and 56 minutes. This 13-hour swing between seasons affects everything from energy levels to tourist planning. Between mid-May and late July, it never gets fully dark: even at midnight, there is sufficient twilight to read outdoors. Conversely, in December, the sun barely climbs 6 degrees above the horizon at noon, producing a permanent golden-hour light that photographers love but which can affect mood and energy. Visitors in winter should plan indoor activities for most of the day and pack a sunrise alarm clock if sensitive to darkness. In summer, bring a sleep mask: blackout curtains are standard in Finnish hotels, but the psychological effect of 19-hour daylight can still disrupt sleep patterns for the first few days. Check our Helsinki travel tips for more information.

What to Pack for Helsinki Weather

• Winter (Nov-Mar): Thermal base layers (merino wool recommended), insulated waterproof boots with good grip for ice, a down parka rated to at least -15°C, wool hat, insulated gloves, and a scarf. Temperatures below -15°C (5°F) are uncommon but happen a few days each winter, so layering is key.
• Spring (Apr-May): Waterproof ankle boots for slush, a mid-weight jacket (down or fleece-lined), hat and gloves for April, lighter layers for May. Bring sunglasses: the combination of low sun angle and snow on the ground in April is blinding.
• Summer (Jun-Aug): Light layers, a sweater or light jacket for evenings (temperatures can drop to 10°C/50°F even in July), comfortable walking shoes, an umbrella or light raincoat for afternoon showers, and swimwear for public saunas and beach visits. Insect repellent for evenings near water.
• Autumn (Sep-Oct): Waterproof jacket and shoes, warm mid-layers, a hat and gloves by mid-October. The wind off the Baltic can be biting, so windproof outer layers are worth the investment.