Helsinki, Finland is most comfortable in May, June, August. The toughest month for heat is February (comfort 77/100). In August, daytime highs average 19.9°C (feels like 19°C) with 0 days over 30°C and 0.6 tropical nights.
| Month | Avg high | Avg low | Feels like | Days ≥30°C | Days ≥35°C | Nights ≥20°C | Comfort |
|---|---|---|---|---|---|---|---|
| January | -0.9° | -5.8° | -6.1° | 0 | 0 | 0 | 78 |
| February | -1.1° | -5.9° | -5.9° | 0 | 0 | 0 | 77 |
| March | 2.4° | -3.3° | -2.1° | 0 | 0 | 0 | 86 |
| April | 7.2° | 0.4° | 3.3° | 0 | 0 | 0 | 98 |
| May | 13.5° | 5.7° | 10.6° | 0 | 0 | 0 | 100 |
| June | 19.5° | 12° | 18.2° | 0 | 0 | 0.2 | 100 |
| July | 21.8° | 15° | 21.2° | 0.2 | 0 | 2 | 98 |
| August | 19.9° | 13.9° | 19° | 0 | 0 | 0.6 | 100 |
| September | 15.6° | 10.4° | 13.7° | 0 | 0 | 0 | 100 |
| October | 9.8° | 5.5° | 6.2° | 0 | 0 | 0 | 100 |
| November | 4.6° | 0.9° | 0.5° | 0 | 0 | 0 | 91 |
| December | 0.4° | -4° | -4.4° | 0 | 0 | 0 | 81 |
No. August daytime highs in Helsinki average a comfortable 19.9°C with 0 days over 30°C — it's a solid summer choice for avoiding extreme heat.
Based on 5 years of climate data, the most comfortable months in Helsinki are May, June, August. The toughest month for heat is February, scoring 77/100 on our heat-comfort index.
In August, nights in Helsinki average a low of 13.9°C, with 0.6 tropical nights per month (nights that stay at or above 20°C) — a key factor for sleep quality if your stay has no air conditioning.
Tell us where and when you're going. If a heatwave becomes likely for your dates, we'll email you early — with cooler day-by-day alternatives nearby.