Weather Trends in Helsinki, FinlandWeather Trends in Helsinki,
Finland

Helsinki experiences a distinct seasonal cycle characterized by frozen winters and mild, pleasant summers. WeatherBox data shows that the thermal profile shifts significantly, with a typical annual variance of 22.6°C (40.7°F) between seasonal extremes. During the coldest period in month February, average nightly lows drop to -7.0°C (19.4°F), and temperatures rarely fall below -17.2°C (1.0°F). In contrast, the warm season brings temperate conditions, with summer averages sitting at 16.7°C (62.1°F). Peak heat arrives in month July, where daily highs average 21.8°C (71.2°F) and rarely exceed 26.8°C (80.2°F).

Sky conditions vary from overcast darkness to prolonged brightness depending on the month. The region records its highest cloud density of 91.5 in month January, coinciding with minimal light in month December when sunshine averages 0.0. Conditions clear significantly by month May, leading to extended daylight in month July with an average of 318.7 hours of sun. Rainfall is frequent but manageable, totaling 758 mm (30 in) per year. The heaviest precipitation falls in month July, accumulating 89 mm (3 in), while the driest spell occurs in month March with only 40 mm (2 in).

Wind and humidity play crucial roles in the perceived comfort of the local environment. Prevailing winds blow from the SW, with the strongest gusts averaging 15.9 km/h (9.9 mph) during month December. These breezes rarely exceed 30.5 km/h (19.0 mph) but can sharpen the winter chill. Relative humidity peaks at a damp saturation of 90.8 in month November, though the air dries out considerably by late spring. Summer offers the highest probability of comfortable humidity, peaking at 60.3 in month July, while the average peak UV Index is 4.5.

Explore our advanced weather charts on the WeatherBox website to visualize these patterns in detail.