Photo: Alan Alves on Unsplash.com

By Laura Durenberger-Grunow - Boreal Community Media - April 29, 2025

A new tool, the "Minnesota Lakes Ice-Out Clock," has been developed by a team from Minnesota Sea Grant to provide more precise predictions for when Minnesota lakes will become navigable, an important piece of information for outdoor lovers and those in the tourism industry. 

The Ice-Out Clock utilizes historical and current data from the National Weather Service, as well as 15,000 historical ice-out dates, lake locations, latitudes, and sizes from the Minnesota Department of Natural Resources. This data is then combined with real-time data from local weather stations, mostly airports, to populate three estimated ice-out dates, which are dependent on the snow cover for a particular region. 

Dr. John Downing, Minnesota Sea Grant project lead, told Boreal Community Media that clock predictions have been very accurate (sometimes within one day) in areas with numerous weather stations and data. However, one challenge lies in rural areas, such as Cook County and the Boundary Waters Canoe Area Wilderness, where that data is not as easily obtained. 

Currently, in Cook County, the only weather station able to provide data for the Ice-Out Clock calculations is the Grand Marais Airport. Those familiar with the county and its terrain know that weather conditions and snow coverage can vary significantly from the North Shore to the Canadian border. With the Ice-Out Clock, the further away a location is from the weather station (in this case, the Grand Marais Airport), the less accurate it is. 

For example, at the time of this posting, many lakes located further inland have a prediction of ice-out being imminent or already occurring. However, some outfitters and residents along these lakes are still reporting 20+" of slush and ice. "It is the fault of having so few reliable weather stations around the state, especially in those beautiful areas that are quite wild," Dr. Downing said. 

Looking back at two of the main purposes of the clock, as stated by MN Sea Grant —outdoor recreation and tourism —this limitation directly impacts proper planning in these areas. 

As a workaround, Dr. Downing suggested looking across counties, such as Lake or St. Louis Counties, "for lakes at about the same latitude and the same size, and follow their forecasts," while also factoring in that "they will also be a bit later than forecast, too, because they are pulling data from Hibbing or International Falls."

The challenge of insufficient weather data in rural areas is further exacerbated by potential funding risks for agencies, like the National Oceanic and Atmospheric Administration (NOAA), as noted by Dr. Downing: "What we really need is more and better weather data. This is kind of unlikely since this kind of thing is done by the NOAA, and their funding seems to be at risk these days." 

The accuracy of predictions is important, according to MN Sea Grant. In Minnesota, outdoor lake recreational activities, including fishing and boating, generate annual economic benefits of $1.14 billion, compared to $240 million for snow-related recreational activities. "Variation in seasonality and a lack of means by which to forecast the timing of recreation seasons are among the most economically impactful pressures on Minnesota’s tourism industry," according to the Ice-Out Clock website. 

Dr. Downing highlights the need for a long-term solution, suggesting, "What we should do in the longer term is to set up a good weather station inland that we can pull data from. That would help quite a bit. It would need to be in a place where there is cell coverage, but electrical power is not needed. If anyone wants to try this, we could get it going for a minimal cost. It would be super useful for monitoring Boundary Waters weather, too." 

He also suggests that individuals with their own weather stations could contribute valuable data to refine forecasts for their specific locations. Additionally, he indicated that those with good temperature records tally up "freezing degree days since October 1 and thawing degree days since January 1." Dr. Downing said that from there, he could help put together forecasts. 

One thing the Ice-Out Clock cannot predict in any area is ice safety, and Dr. Downing and MN Sea Grant remind users that no ice is 100% safe. 

To learn more about the Ice-Out Clock, visit the MN Sea Grant website here.