Outdoor ice safety: how thick should ice be for skating?

The Minnesota DNR's current poster gives these minimums, labeled as guidelines for new, clear ice only. Skating is an activity on foot, so the figure for skaters is 4 inches of new, clear ice.

The same poster says to double the thickness guidelines for white ice, which puts the on-foot minimum at 8 inches when the ice is white. The Wisconsin DNR likewise advises looking for clear ice, which it says is generally stronger than ice with snow on it or bubbles in it.

Age matters too. The Minnesota DNR's Danger! Thin Ice brochure says new ice is usually stronger than old ice: 4 inches of clear, newly formed ice may support one person on foot, while a foot or more of old, partially thawed ice may not. Snow insulates the ice and slows freezing, and its weight reduces how much the ice can support; the DNR advises shoveling snow away before testing the ice for thickness and color. The Indiana DNR adds that thick ice is rotten after rain, and that old honeycombed ice, slush ice and ice with current under it are dangerous.

Guidelines also vary by agency. The Indiana DNR, for example, tells anglers to drill a test hole near shore and look for at least four inches of clear ice, and its guidelines for fresh, solid ice give five inches for snowmobiling, eight for a car or light truck and ten for a medium-weight truck.

Ice seldom freezes evenly. The Minnesota DNR says it may be a foot thick in one place and only an inch or two a few feet away, and that ice near shore can be weaker than ice farther out. Its brochure lists the danger spots:

Check the thermometer, not the calendar: the Minnesota DNR points out that ice that was safe on a date last year may not be safe on the same date this year. Ask local experts for current reports; the Wisconsin DNR says local bait shops, fishing clubs and resorts often have the most up-to-date information on ice thickness and hazards.

Measure as you go. The Minnesota DNR brochure says to check ice thickness every 150 feet at a minimum, using an ice chisel or drill and a tape measure, and the 2023 poster repeats that thickness varies and should be checked as you go.

Minnesota DNR guidance is to wear a life jacket or float coat on the ice (except inside a vehicle) and to carry an ice safety kit: rope, ice picks, an ice chisel or drill and a tape measure. The poster adds that ice picks should be immediately accessible. Tell someone where you are going and when you expect to be back, and carry a phone or personal locator beacon.

The Wisconsin DNR's list is similar: dress warmly in layers, do not go alone, avoid unfamiliar areas and do not go out at night or in reduced visibility, and carry ice claws or picks, a phone in a waterproof bag, a life jacket and a length of rope.

The Minnesota DNR's survival steps: do not panic, and get your breathing under control. Keep your winter clothing on, since it traps air for warmth and flotation. Turn back toward the direction you came from, which is probably the strongest ice, and call for help. Put your hands and arms on the unbroken surface, dig in your ice picks and kick your feet to work your way out. Once out, lie flat and roll away from the hole to spread your weight, then get somewhere warm and dry; moderate to severe cold-water hypothermia needs medical attention.

The Minnesota DNR teaches five steps, in order: preach, reach, throw, row, don't go.