Lake ice thickness from the weather
An online tool for estimating ice thickness: from the frosts, snow and thaws since the start of the season it works out when the ice formed and how thick it is now on a lake, pond or river, and shows a range next to the official guidance. The model was checked against thousands of real measurements, and its error is printed on the page.
How to use it
A town nearby or your location.
Pond, lake, large lake or river.
If you measured it, the estimate gets sharper.
Find out how much ice may have grown on your lake
Choose a place — the tool takes the weather since the start of the season and works out the ice.
Ice since the start of the season and a week ahead
How accurate the estimate is
The model was tested on open measurements of the Finnish Environment Institute (SYKE); every lake was checked by a model fitted without it.
- 12,303 measurements on 66 lakes, seasons 2008–2026: average error 7.5 cm (3 in), in eight cases out of ten no more than 11.7 cm (4.6 in).
- Ice thinner than 20 cm (8 in): average error 9.7 cm, and in 31% of cases the model overstated the ice by 5 cm (2 in) or more.
- With your measurement: the next measurement four to ten days later was missed by 3.3 cm (1.3 in) on average.
- Water temperature before freeze-up: average error 1.3 °C over 93,458 daily measurements.
Finnish lakes resemble lakes of the northern US, Canada and Scandinavia, not southern waters or rivers — there the error may be larger.
Ice thickness guidance
The Minnesota Department of Natural Resources gives this guidance for new clear ice:
- 4 in (10 cm) — walking
- 5–7 in (13–18 cm) — snowmobile or ATV
- 8–12 in (20–30 cm) — car
- 12–15 in (30–38 cm) — pickup truck
White, slushy, thawed and spring ice holds less at the same thickness.
How the ice is worked out
First the water temperature is estimated from the air of the past weeks; when the surface cools to near freezing on a frosty day, the first ice forms.
From then on the ice grows from below by as much heat as the cold draws out through the ice and the snow on it. Snow comes from NASA POWER data; heavy snow pushes the ice under, water floods it and freezes into white ice, which counts too.
In a thaw the snow melts first, then the ice from the top. Every constant was fitted on open measurements on Finnish lakes with the same weather data the page gets.
This is an estimate from the weather, not a measurement. It cannot see springs, current, open holes, cracks or ice weakened by a thaw. Check the ice with an auger or spud bar every few steps and never go out on it alone.
Weather of past weeks and snow — NASA POWER; forecast — MET Norway (CC BY 4.0) and DWD; model testing — open data of SYKE (Finnish Environment Institute, CC BY 4.0).