Frost Laws Explained: What Every Trucker Needs to Know

What Are Frost Laws?

Frost laws establish weight restrictions that apply in cold-weather states during the period from late winter to early spring. The freezing and thawing process destroys road strength because thawing reveals hidden damage that exists below the road surface. States need to reduce weight limits on specific roads because excessive traffic would cause major damage to those routes.

Why Frost Laws Exist

During the freeze–thaw cycle:

• Ice forms beneath the pavement
• Thawing creates a soft muddy base that supports the road subgrade.
• Heavy trucks can break roads through cracking or creating ruts or total destruction.

Frost laws protect:

• Local roads for communities and local governments
• Infrastructure that receives funding from taxpayers
• Routes that provide emergency access

When Frost Laws Are in Effect

Frost laws typically apply:

• Late February through May
• Frost laws apply based on three factors: weather conditions, soil characteristics, and geographic area.
• The roadbed needs to reach complete drying and stabilization before the ban gets lifted.
• States declare their yearly start and end times but weather conditions can create rapid changes.

How Frost Laws Affect Truckers

If you’re operating during frost season you may face:

• Reduced gross vehicle weight limits
• Lower axle weight limits

Certain roads have traffic limitations which do not apply to highways.

Heavy fines apply for any violations of which violations result in penalties at all locations.

Some roads may drop from:

80,000 lbs ➝ 60,000 lbs (or lower)

Common Frost Law States

Frost laws operate in northern states and Midwestern states which include:

• Minnesota
• Wisconsin
• Michigan
• North Dakota
• South Dakota
• Iowa
• Montana
• Maine

Each state (and even counties) sets its own rules.

Frost Law Load Adjustments

To stay compliant truckers must complete the following tasks:

• Haul lighter loads
• Increase the number of trips
• Re-route to frost-law-exempt highways

Apply for special permits (when allowed)

Planning loads without checking frost laws can kill profits fast.

Permits and Exemptions

Some states allow:

• Frost law permits for essential commodities
• Higher limits on designated all-weather roads
• Emergency or agricultural exemptions

Permits become limited resources which do not guarantee approval for all applicants.

Penalties for Violations

Ignoring frost laws can result in:

• Heavy fines per axle
• Out-of-service orders
• Liability for road damage
• Increased audit risk

Enforcement is usually strict during thaw season.

Best Practices for Truckers

• Truckers need to verify state DOT frost law changes every day.
• Truck drivers should create route plans before they start loading their vehicles.
• Shippers need to share their seasonal limitations with dispatchers.
• Dispatchers need to be trained on the various frost-law zones.

Why Frost Laws Matter for Compliance

Frost laws connect with all three operational areas of:

• Route planning
• Load optimization
• Cost control
• DOT compliance
• To operate their businesses without interruption.

A single violation costs an owner-operator or small fleet operator all their earnings for the entire week.