Helsinki weather in September
September is a fair month to visit Helsinki: highs of 15°C (59°F) and about 63 mm (2.5 in) of rain on average. Nights average 12°C (53°F) and cloud cover 67% (NASA POWER, 2001–2025 averages). The sea averages 17°C (62°F). It is the 6th wettest month of the year and the 4th warmest. Compared with August, it is cooler and about as wet; October brings highs of 9°C (48°F) and 80 mm (3.1 in) of rain.
Is September a good time to visit Helsinki?
fair month Weather score 61/100.
September is a fair month in Helsinki. The weather is usually best in Jun–Aug.
Does it rain a lot in Helsinki in September?
Some rain is normal: about 63 mm (2.5 in) falls in an average September. It is the 6th wettest month of the year.
How warm is Helsinki in September?
Days average 15°C (59°F) and nights 12°C (53°F).
Helsinki weather by month
| Month | High | Low | Rain | Cloud | Sea | Weather |
|---|---|---|---|---|---|---|
| January | -1°C (29°F) | -4°C (24°F) | 56 mm | 82% | 0°C (33°F) | least pleasant |
| February | -2°C (28°F) | -5°C (22°F) | 45 mm | 79% | 0°C (32°F) | least pleasant |
| March | 0°C (33°F) | -3°C (26°F) | 42 mm | 69% | 1°C (34°F) | least pleasant |
| April | 5°C (42°F) | 1°C (34°F) | 41 mm | 67% | 4°C (40°F) | least pleasant |
| May | 11°C (52°F) | 6°C (43°F) | 48 mm | 62% | 10°C (50°F) | fair |
| June | 16°C (60°F) | 11°C (53°F) | 66 mm | 66% | 16°C (61°F) | best |
| July | 20°C (67°F) | 16°C (60°F) | 59 mm | 64% | 19°C (66°F) | best |
| August | 19°C (66°F) | 15°C (60°F) | 71 mm | 63% | 20°C (68°F) | best |
| September | 15°C (59°F) | 12°C (53°F) | 63 mm | 67% | 17°C (62°F) | fair |
| October | 9°C (48°F) | 6°C (43°F) | 80 mm | 78% | 11°C (52°F) | least pleasant |
| November | 5°C (40°F) | 2°C (36°F) | 75 mm | 85% | 7°C (44°F) | least pleasant |
| December | 1°C (34°F) | -1°C (29°F) | 67 mm | 85% | 4°C (38°F) | least pleasant |
Sources: 2001–2025 monthly averages from NASA POWER (MERRA-2 reanalysis), sea temperature from Open-Meteo Marine. Page updated . How we rate months