Frost Laws by State — Spring Weight Restrictions
Complete guide to seasonal weight restrictions across the US. Know when frost laws activate, how much weight is reduced, and which routes are exempt — before your load gets turned away.
What Are Frost Laws?
Frost laws (also called spring weight restrictions or seasonal load restrictions) are temporary weight limits imposed by states during spring thaw. When frozen roads thaw, the subgrade becomes saturated and weakened — heavy loads can cause permanent road damage. States reduce allowable axle weights by 10–35% to protect infrastructure.
For heavy haul and oversize load operations, frost laws can shut down entire corridors for 6–12 weeks. Planning around these restrictions is critical for avoiding delays, fines, and road damage liability.
Most states activate frost laws between mid-February and late March, with restrictions lasting through April or May. Check your specific route states before dispatching any oversize or heavy haul loads during this window.
Frost Laws by State — Quick Reference
| State | Typical Season | Weight Reduction | Severity | Notes |
|---|---|---|---|---|
| Minnesota | Mar 1 – May 15 | 10% on 10-ton roads | high | MnDOT publishes county-by-county road restrictions |
| Wisconsin | Mar 1 – May 1 | Up to 6 ton/axle reduction | high | Posting dates vary by county |
| Michigan | Feb 15 – May 15 | Up to 35% reduction | high | Weight restrictions on all seasonal roads |
| North Dakota | Mar 1 – May 31 | 10-ton limit on county roads | high | Interstate highways exempt |
| South Dakota | Mar 1 – Apr 30 | Variable by road class | high | Governor issues proclamation |
| Montana | Mar 15 – May 15 | Up to 6,000 lb/axle reduction | medium | MDT publishes restriction maps |
| Idaho | Feb – Apr (variable) | Up to 20% reduction | medium | Varies by highway district |
| Vermont | Mar 1 – May 15 | 24,000 lb GVW on Class 3 roads | high | Town highways most restricted |
| New Hampshire | Mar – May (variable) | Up to 6 ton/axle reduction | medium | Municipal roads primarily affected |
| Maine | Mar – May (variable) | 23,000 lb limit on posted roads | medium | Posted road restrictions |
| Iowa | Feb 15 – May 15 | Farm-to-market roads restricted | medium | County-level restrictions |
| Nebraska | Mar 1 – Apr 30 | Variable by county | medium | County boards set restrictions |
| Pennsylvania | Feb – Apr (variable) | Reduced weight on posted roads | low | PennDOT weight posting system |
| New York | Mar – Apr (variable) | Town road restrictions | low | Local highway superintendents post |
| Oregon | Variable | Seasonal restrictions on select routes | low | ODOT freeze/thaw program |
| Washington | Variable | Seasonal restrictions on select routes | low | WSDOT seasonal postings |
| Wyoming | Mar – May (variable) | Up to 20% on local roads | medium | County-managed restrictions |
| Indiana | Feb – Apr (variable) | County road weight embargoes | low | County highway departments manage |
| Illinois | Feb – May (variable) | Local jurisdiction restrictions | low | County and township roads |
| Ohio | Feb – May (variable) | County engineer weight limits | low | Posted road restrictions |
How to Plan Around Frost Laws
Check Dates Early
Monitor your state DOT for frost law announcements 2-4 weeks before typical start dates. Book escorts and permits before restrictions activate.
Use All-Season Routes
Many states designate "all-season" routes exempt from frost laws. Plan your haul along these corridors when possible.
Reduce Axle Weights
If you can't avoid frost law roads, reduce axle weights to comply. This may mean splitting loads or adjusting trailer configurations.
Pre-Position Equipment
Stage equipment before frost laws activate. Pre-positioned loads on all-season routes avoid restrictions entirely.
Frequently Asked Questions
Get the Full Compliance Package
Pre-filled permit applications, weight restriction summaries, all-season route maps, and escort requirements — all in one downloadable packet per state. Stop guessing, start complying.