Portland, Maine – River ice across Maine and New Hampshire continues to thicken this winter, increasing the risk for ice jams that can cause sudden and unpredictable changes in river levels.
According to the National Weather Service in Gray, river ice is already extensive across much of Maine and New Hampshire and is expected to continue forming and thickening through February. Once ice thickness reaches approximately four inches or more, the likelihood of ice jams increases, particularly in areas where ice can pile up or shift.
While antecedent drought conditions are currently keeping the overall flood risk low, forecasters caution that shifting river ice can still trigger rapid water rises, even without heavy rainfall or snowmelt. Ice jams can form suddenly and may cause localized flooding upstream or downstream with little warning.
Areas of concern include rivers near Interstate 95, U.S. Route 202, U.S. Route 302, and U.S. Route 16, especially near bridges and bends where ice is more likely to accumulate. The Kennebec River, Saco River, and other major waterways are being closely monitored for signs of developing jams.
Because river gauges often cannot detect ice jams, the National Weather Service is asking the public to help by reporting observations. Officials encourage residents, emergency managers, and spotters to report ice piling up, slowing water flow, ice breaking up, or water backing up or flooding. Photos taken from a safe location are especially helpful. The public is urged never to go onto river ice.
Reports can assist forecasters in issuing timely flood messaging and warnings if conditions change.
This monitoring effort will continue throughout the winter as freeze-up and break-up cycles occur.
Residents, commuters, and infrastructure managers near rivers and bridges along I-95 and other major roadways should remain aware of changing river conditions in the weeks ahead.
