| Month | High | Low | Rain | Wet days | Score |
|---|---|---|---|---|---|
| January | -1° | -5.8° | 54.9mm | 15.9 | 3 |
| February | -1° | -6.1° | 42.9mm | 13 | 7 |
| March | 2.4° | -3.6° | 32.5mm | 10.3 | 16 |
| April | 8.3° | 1.2° | 34.2mm | 9.6 | 42 |
| May | 14.6° | 6.6° | 39.2mm | 9.4 | 64 |
| June | 19.4° | 11.6° | 57.7mm | 10.8 | 76 |
| July | 22° | 14.7° | 58.1mm | 11.1 | 78 |
| August | 20.7° | 13.7° | 81.1mm | 11.8 | 76 |
| September | 15.7° | 9.6° | 55.4mm | 10.9 | 64 |
| October | 9.5° | 4.7° | 74.5mm | 13.8 | 39 |
| November | 4.6° | 0.7° | 70.6mm | 15.7 | 19 |
| December | 1.2° | -3.3° | 59.5mm | 15.8 | 7 |
January in Helsinki averages a daily high of -1°C with nights around -5.8°C. Expect roughly 15.9 wet days totalling 54.9mm. A hard month to visit for comfort alone.
February in Helsinki averages a daily high of -1°C with nights around -6.1°C. Expect roughly 13 wet days totalling 42.9mm. A hard month to visit for comfort alone.
March in Helsinki averages a daily high of 2.4°C with nights around -3.6°C. Expect roughly 10.3 wet days totalling 32.5mm. A hard month to visit for comfort alone.
April in Helsinki averages a daily high of 8.3°C with nights around 1.2°C. Expect roughly 9.6 wet days totalling 34.2mm. Demanding conditions — pack for it and plan indoor options.
May in Helsinki averages a daily high of 14.6°C with nights around 6.6°C. Expect roughly 9.4 wet days totalling 39.2mm. Generally workable, with some weather to plan around.
June in Helsinki averages a daily high of 19.4°C with nights around 11.6°C. Expect roughly 10.8 wet days totalling 57.7mm. Comfortable conditions for being outdoors all day.
July in Helsinki averages a daily high of 22°C with nights around 14.7°C. Expect roughly 11.1 wet days totalling 58.1mm. Comfortable conditions for being outdoors all day.
August in Helsinki averages a daily high of 20.7°C with nights around 13.7°C. Expect roughly 11.8 wet days totalling 81.1mm. Comfortable conditions for being outdoors all day.
September in Helsinki averages a daily high of 15.7°C with nights around 9.6°C. Expect roughly 10.9 wet days totalling 55.4mm. Generally workable, with some weather to plan around.
October in Helsinki averages a daily high of 9.5°C with nights around 4.7°C. Expect roughly 13.8 wet days totalling 74.5mm. Demanding conditions — pack for it and plan indoor options.
November in Helsinki averages a daily high of 4.6°C with nights around 0.7°C. Expect roughly 15.7 wet days totalling 70.6mm. A hard month to visit for comfort alone.
December in Helsinki averages a daily high of 1.2°C with nights around -3.3°C. Expect roughly 15.8 wet days totalling 59.5mm. A hard month to visit for comfort alone.
Each month scores out of 100. It starts at 100 and loses points for daytime highs outside a 20–27°C band, for wet days, and for nights below 2°C. Nothing else is weighted in — no crowd data, no prices, no opinion. Helsinki peaks at 78.
Based on 30 years of records, June–August scores highest for comfort in Helsinki, balancing daytime temperature against rainfall.
July is the warmest, averaging a daily high of 22°C.
August is the wettest, averaging 81.1mm of rain across roughly 11.8 wet days.
January is the coolest month, with average daily highs around -1°C.