Although the temperatures have dropped again, the recent warm stretch of weather has the Michigan DNR reminding people to exercise extreme caution on the ice. Officials say just because a body of water may appear frozen, don’t assume it’s safe to walk on. Fluctuating temperatures compromise the integrity of the ice and can cause it to become weak or spongy. Ice covered by snow should always be presumed unsafe as snow insulates the ice and slows the freezing process. DNR guidelines state a minimum of four inches of clear ice is needed to support the weight of an average person, and because ice doesn’t typically form at a uniform rate, it is important to check the thickness every few feet. Anyone travelling on the ice should wear a life jacket and brightly colored clothing and carry a cellphone and a set of ice picks.