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Jäätilannekartta esittää pistemäisten havaintojen lisäksi ennustemallin laskemat arviot. Jäälle ei pidä mennä pelkän kartan arvioiden perusteella, sillä paikallinen vaihtelu voi olla suurta! Etenkin heti jäätymisen jälkeen jää voi olla paljon heikompaa virtapaikoissa ja selkävesillä kuin vaikkapa ranta-alueilla. Keväällä, kun lumi on sulanut, aurinko voi haurastuttaa paksunkin jään jo parissa tunnissa petollisen heikoksi.

Ice situation 1.12.2023

Small lakes in southern and central Finland are frozen, large lakes remain unfrozen

The ice thickness is monitored three times a month, always on the 10th, 20th and 30th day.

The estimated ice situation is based on observations

The Finnish Environment Institute updates the estimate of the ice situation on this page three times a month. The estimate is based on ice thickness measurements at 46 observation sites in different parts of Finland. The ice thickness is measured approximately on the 10th, 20th and 30th day of every month.

You can view the latest observations on the ice situation map (available in Finnish and Swedish). Everyone can also record their own ice observations, making them appear on the map. The Finnish Environment Institute does not verify these observations. You should not go on the ice solely based on the estimates and observations on the map because ice quality and thickness vary greatly even within the same lake and between different waterbodies.

You can observe the general development of the ice situation by a computational estimate of ice thickness, i.e., the colours on the map. The estimate is made by modelling, and it utilises ice thickness observations as well as weather data and forecasts, for instance. It is not possible to determine the actual ice thickness of any waterbody based on the ice situation map. The ice thickness observations are only representative of the specific site on the date of the measurement and are therefore indicative and cannot be extrapolated to large areas.

Further information


Ihmiset ulkoilevat kevätjäällä Siilinkarin majakan edustalla Tampereen Pyhäjärvellä

Stay safe on ice from autumn till spring

If you intend to go out on ice, you should always make sure that it is strong enough on the route you intend to take. Get to know the properties of ice in different seasons and pay attention to possible hazards.

Autumn ice

The water starts freezing in autumn when its surface temperature drops below zero. Shores and bays are the first to freeze over, while any deep areas and places with a current get their ice cover last. It is typical for ice thickness to vary in different areas of a lake or the sea in autumn. Measure the thickness of the ice on your route to be sure that it will carry you. Transparent clear ice must be at least five to ten centimetres thick before it carries a person walking on it.

Spring ice

As the air grows warmer and the sun’s radiation becomes stronger in spring, the snow and ice cover starts to melt. Once the snow is gone and solar radiation starts melting the ice, its structure becomes more fragile and cavities appear in the ice layer, and you can no longer conclude the bearing strength of the ice by measuring its thickness. Even if it were 20 to 30 centimetres thick, the ice can be too fragile to carry the weight of a person.

Hazardous areas

Particularly hazardous areas are straights, deep areas and places with a current, including at river mouths and near springs, sewers and stormwater drains, where the ice may remain thin throughout the winter. You should also monitor the ice thickness near large stones, docks and other structures as well as aquatic plants. Shipping lanes, and cracks and holes cut in the ice, are dangerous even in mid-winter. Snow cover makes it more difficult to spot areas of weak ice.

Fun facts about ice