Weather in Helsinki, month by month

Warmest month: July, 17.6
Coldest month: February, -3.9
Wettest month: October, 80 mm
Year: 2001-2020

Same data, same method, different place.

Your own numbers, worked out on the page.

Across the 2001-2020 normals, the warmest month in Helsinki is July at 17.6 degrees and the coldest is February at -3.9, a swing of 21.5 degrees over the year. Those are monthly averages for the model cell the city sits in, not readings from a weather station in it.

Rain is heaviest in October, about 80 mm, and lightest in April at roughly 41 mm. Over a full year the cell above Helsinki collects around 712 mm.

The months whose average sits between 15 and 24 degrees are July and August. That band is this page's own definition of mild and is stated so you can disagree with it rather than guess at it.

Humidity peaks in February at 94 percent, and the windiest month is December at 4.8 metres per second. Both are monthly means from the same twenty year series as the temperatures.

Rainfall is not spread evenly: 58 per cent of the year total falls in July, August, September, October, November and December.

4 months average below freezing: January, February, March and December.

Every figure here comes from one NASA POWER grid cell, at 60.17, 24.94, covering Helsinki on the 2001-2020 climatology. One cell, one period and one provider for every month, which is what makes the twelve rows comparable with each other.

The source publishes a monthly mean and, separately, the highest and lowest values it recorded in twenty years. Those extremes are not a typical afternoon or a typical night, so nothing here is quoted as one. This page does not say what the daytime high usually is, because this source cannot say it.

Normals are not a forecast. They describe what twenty years averaged to, and any single year can sit well outside them. They also describe a model grid cell of roughly fifty kilometres rather than a weather station, so a coastal city and the sea beside it share one figure.