2021 Spring Thaw

Each year, many areas in the US and Canada implement temporary special weight limits and restrictions on roads and highways during the winter and spring months. These temporary measures are referred to as “frost” or “thaw” laws and are implemented on an “as needed” basis. During the months of March through June, some jurisdictions will reduce speed limits and legal axle weights to protect our road structures. The commercial carrier must comply with these restrictions to avoid penalty and or the cost of having to reduce axle weight.

Why Are There Spring Thaw Weight Restrictions?

These temporary restrictions are designed to reduce damage to our roadways at the most vulnerable time of year when there’s excess moisture present. Safer roads means safer driving for everyone.

While road building technology has significantly improved, our roadways are still susceptible to increased damage when there’s excess moisture present. The most common occurrence is potholes formed on the weakened top layer of the road. Many of us have probably hit a pothole at one point and can attest to how uncomfortable and/or damaging they can be. Excessive weight from overloaded vehicles can also cause the road to bend or deform.

When Are Seasonal Weight Restrictions In Place?

Always check with your local department of transportation before you go. In general, most frost laws will begin around March 1st and can last until June or July. This can vary by year and depends on what the temperatures were during the winter months in that area.

What Are The Penalties For Not Reducing Axle Weights?

Monetary penalties can be quite expensive for failing to abide by these temporary restrictions and vary by region. However, the more costly consequences to disregarding the frost laws include vehicle downtime, performance, and road safety. If caught, the carrier will be forced to pull over and arrange for the excess weight to be removed or adjusted and will receive negative remarks on their safety rating. Damaged roads also cause excessive damage to the carrier’s vehicles as well as all other vehicles on the roadways, causing an increased likelihood of accidents.

What Are The Spring Thaw Weight Restrictions In My Area?

Spring weight restrictions vary widely by state and province and are often posted on short notice. Before your next trip, be sure to check out the list below for more information on the thaw laws for your region!

Spring Thaw Dates

1) British Columbia: Spring thaw dates differ by region

2) Alberta: Weather dependent subject to thaw depth readings

3) Saskatchewan

• South: March 15 – June 15
• North: April 1 – June 30

4) Manitoba

• Zone 1A: March 1 – May 29
• Zone 1B: March 6 – May 31
• Zone 2: March 6 – May 31
• Zone 3: March 12 – June 10

5) Ontario

• Schedule 1 Highways: March 1 – April 30
• Schedule 2 Highways: March 1 – May 31
• Schedule 3 Highways: March 1 – June 30

6) Quebec

• Zone 1: March 8 – May 7
• Zone 2: March 15 – May 14
• Zone 3: March 22 – May 21

7) New Brunswick

• South: March 1 – May 16
• North: March 8 – May 23

8) Nova Scotia: No Longer in Effect

9) Prince Edward Island: No Longer in Effect

10) Newfoundland: N/A

Canada Frost Laws 

• Alberta
• British Columbia
• Manitoba
• New Brunswick
• Northwest Territories
• Nunavut
• Nova Scotia
• Ontario
• Prince Edward Island
• Quebec
• Saskatchewan
• Yukon

US Thaw Laws

• Idaho
• Iowa
• Maine
• Michigan
• Minnesota
• Montana
• Nevada
• New Hampshire
• New York
• North Dakota
• Pennsylvania
• South Dakota
• Vermont
• Washington
• Wisconsin
• Wyoming