Frost Depths in Minnesota Deepest Since 2019

UNDATED (WJON News) -- As we brace for another cold front early next week in Minnesota, the ground below us is pretty frozen too.

The Minnesota State Climatology Office says the frost depths under the sod for the week of January 27th are the deepest frost for the date since 2019. Of course, frost depths across the state vary.

The frost depth is measured by a simple instrument called a frost tube. The liquid freezes in the tube as the ground becomes colder. Frost depth readings are updated by the United States Army Corps of Engineers on a weekly basis.

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Snow can insulate the ground from the air above it and studies have shown that about four inches of fluffy snow will form an effective layer of insulation. When there is a deep snow pack, there can be little to no frost in the ground. Where the landscape is free of snow, the frost can penetrate much deeper.