Iowa Frost Laws & Spring Thaw Limits

How Iowa handles spring thaw

Iowa's frost restrictions come from the counties, not one statewide order. A county can embargo its roads for up to 90 days a year when thaw, rain, or snow would tear them up (Iowa Code 321.471). A typical embargo caps gravel roads at 5 tons and hard-surfaced roads at 10 tons, set by the county engineer, and the posted embargo sign is the legal limit there. Interstates and state primary highways aren't seasonally posted. Call the county engineer each spring.

Window, reduction, and where to check

• Season: Spring thaw, set locally for up to 90 days a year. County embargoes typically go on as the ground thaws in late winter and spring; timing varies by county and year.
• Reduction: Set by the county, not a statewide percentage. A common embargo caps gravel roads at 5 tons and hard-surfaced roads at 10 tons gross; the posted embargo sign is the legal limit on that road.
• Interstates: Exempt from the seasonal reduction
• Find the current order: Iowa has no single statewide frost map. Check with the county engineer / county road department for each route, watch for posted embargo signs, and call Iowa DOT Motor Carrier Services at 515-237-3264.
• Overweight penalty: $2 for every 100 lb you run over the posted embargo limit (Iowa Code 321.471(1)(b)). That is its own schedule, not the statewide overweight fines in Iowa Code 321.463, which start at $12 for up to 1,000 lb over and climb steeply from there.

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