Out on Thin Ice - Safety Tips from the Illinois Department of Natural Resources

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Ice Facts

• New ice is usually stronger than old ice. Four inches of clear, newly formed ice may support one person on foot, while a foot or more of old, partially thawed ice may not.
• Ice seldom freezes uniformly. It may be a foot thick in one location and only an inch or two just a few feet away.
• Ice formed over flowing water and currents is often dangerous. This is especially true near streams, bridges and culverts. Also, the ice outside river bends is usually weaker due to the undermining effects of the faster current.
• The insulating effect of snow slows down the freezing process. The extra weight also reduces how much weight the ice sheet can support. Also, ice near shore can be weaker than ice that is farther out.
• Booming and cracking ice isn't necessarily dangerous. It only means that the ice is expanding and contracting as the temperature changes.
• Schools of fish or flocks of waterfowl can also adversely affect the relative safety of ice. The movement of fish can bring warm water up from the bottom of the lake. In the past, this has opened holes in the ice causing snowmobiles and cars to break through.

​Here are the ice thickness safety guidelines:

• 2" or less - STAY OFF
• 4" - Ice fishing or other activities on foot
• 5" - Snowmobile or ATV
• 8" - 12" - Car or small pickup
• 12" - 15" - Medium truck

Note: These guidelines are for new, clear solid ice and many factors other than thickness can cause ice to be unsafe.

Note: White ice or "snow ice" is only about half as strong as new clear ice. Double the above thickness guidelines when traveling on white ice.

Additional Safety Tips:

• It's a good idea to always carry with you a rope or floatation device to help someone who may have fallen through the ice. Remember NOT to approach the area where someone has fallen through, as this ice will be quite vulnerable to weight.
• Wear a personal floatation device (life vest) under your winter gear.
• Carry a pair of ice picks. It's very difficult to pull yourself back onto the surface of slippery ice while weighted down with heavy clothing. The ice picks really help pulling yourself back onto solid ice.

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