Tyre forecast · Finland

When to change winter tyres?

Regional map
Over 27 days to swap Under 27 days to swap Under 10 days to swap Under 3 days to swap

When do winter tyres have to go on?

In Finland the use of winter tyres depends on conditions, not on the calendar: under the Road Traffic Act (tieliikennelaki 729/2018), in force since June 2020, winter tyres must be used from November to March when the weather or road conditions require it. The law does not name a date, so the decision rests with the driver. More on when winter tyres are mandatory.

That is why the right answer differs by hundreds of kilometres on the same day. When Utsjoki is already driving on winter roads, Hanko can have weeks of summer tyre weather left. Rengasennuste turns the weather and road surface forecast into an answer for each municipality, so the decision rests on your own area rather than on a national average.

The rule of thumb: when the road surface starts dropping below freezing at night, it is time to change. The colour on the map says how long you have: amber means it is time to book an appointment; red means winter conditions have already started.

What do the map's colours mean?

The colour says how soon the road turns wintry — not how cold it is. Each colour is a window in days, and in autumn that window is also the deadline for the change. It is read off the road surface rather than the air temperature. They are not the same thing: on a clear night the road cools below the air, and that difference is exactly what decides when there is ice on the road.

  • Green — no wintry road for 27 days. The road surface stays above freezing for the whole forecast period, and the three-week outlook shows no turn either. Summer tyres are enough.
  • Yellow — a wintry road is possible within 27 days. Nothing happens in the coming days, but in the three-week outlook the daily mean drops below +7 °C and night frosts are expected. In autumn: there is still time, and booking is not yet urgent. In spring: winter can still return, so wait.
  • Amber — a wintry road within 10 days. The road surface may freeze within the forecast period. That is roughly the notice a tyre shop appointment needs, so in autumn this is the colour where it starts to matter.
  • Red — a wintry road within 3 days, or already. The road surface freezes within three days, or wintry precipitation is on the way. In autumn, winter tyres are needed now.
  • Grey: no forecast was available for the municipality. A missing forecast is never assumed to be green.

The windows are nested rather than consecutive: a red municipality is also inside ten days, and the colour always states the shortest time that can be claimed. Yellow rests on a different forecast from the others — MET Norway's three-week outlook, which speaks about air temperature, because the road surface cannot be modelled that far ahead.

In spring the same window means the opposite instruction. Red is then not a prompt to change but the reverse: winter conditions continue, so keep the winter tyres on. In spring it is green that says “you can change now”. The full table and how the model computes it are on how the forecast works.

When can winter tyres come off?

The same question the other way round, and in law the same answer: you may change back to summer tyres as soon as conditions no longer require winter tyres. The map does not suggest it on the first mild day, though. It turns green only once no freezing night is left in the forecast period, because a return of winter is ordinary in Finland.

Spring's one fixed date is 31 March: it ends both the winter tyre season and the studded tyre season, the latter subject to the weather-based exception. When can winter tyres come off?