Michigan’s frost laws end on a rolling schedule between early March and late May, with the Michigan Department of Transportation (MDOT) lifting seasonal weight restrictions region by region as the ground firms up. Southern Michigan clears first, the northern Lower Peninsula follows in April, and the Upper Peninsula is usually last, sometimes not until May. Michigan law sets March, April, and May as the default months for seasonal weight restrictions, but MDOT can suspend them earlier when conditions allow.1Michigan Legislature. MCL 257-722
The Regional Lift Pattern
Frost laws don’t flip off statewide on a single day. MDOT imposes and lifts them in geographic phases based on actual ground conditions, so routes in one part of the state can return to normal loading weeks before routes a few hours north.
The 2026 season shows how the pattern plays out. MDOT imposed restrictions on February 17 for state highways from the Indiana and Ohio borders north to a line roughly following US-10 and US-127 through the central Lower Peninsula, and placed the Upper Peninsula under restrictions the same day.2Michigan Department of Transportation (MDOT). Annual Spring Weight Restrictions Begin Tuesday to Protect Michigans Roads Southern Michigan state highways then cleared on March 9, 2026, while areas to the north stayed restricted.3Michigan Department of Transportation (MDOT). Annual Spring Weight Restrictions Changing Monday, March 9
Exact dates shift from year to year, but the sequence is consistent. If you’re hauling freight in Michigan, plan for a restriction window that runs roughly mid-February through mid-May, with the specific roads you use clearing at different points inside that span.
Local Roads Follow Their Own Schedule
MDOT only controls the roughly 10,000 miles of state trunkline highways (routes carrying M, I, or US designations). County road commissions and city public works departments set their own start and end dates for the roads they control, and those dates don’t always line up with MDOT’s.
In 2026, Calhoun County lifted its restrictions on March 16, a week after MDOT cleared southern state highways.4Calhoun County, MI. Seasonal Weight Restrictions Sterling Heights began enforcing restrictions on February 23, 2026, with the city noting they remain in effect until lifted or after May 31, whichever comes first.5Sterling Heights, MI – Official Website. Commercial Motor Vehicle Seasonal Weight Restrictions A route that uses both state and local roads can have one segment running at full legal weight and another still restricted on the same day.
Why the End Date Moves Each Year
MDOT doesn’t pick lift dates off a calendar. Crews monitor actual ground conditions with frost tubes embedded in soil along state highways. The tubes contain a solution that changes color when it freezes, letting crews see how deep the frost extends.6Michigan Department of Transportation (MDOT). News – New Soil Freezing Model May Help MDOT Lower Springs Toll on Our Roads MDOT also pulls data from Road Weather Information System stations that measure ground temperatures across the highway network, and uses statistical models that estimate frost depth from weather data to supplement the manual readings.
The agency’s goal is to keep restrictions in place long enough for the roadbed to drain and regain strength, but not so long that carriers lose money hauling partial loads on roads that are already firm. That’s why a warm spring can bring an early lift and a cold one can push the final clearances in the U.P. into May.
How to Confirm Restrictions Have Ended on Your Route
MDOT publishes spring weight restriction bulletins that update as conditions change. The current bulletin and the Truck Operators Map, which shows which routes are seasonal and which are all-season, are both linked from the MDOT Truckers page at michigan.gov/mdot/business/truckers.7Michigan Department of Transportation (MDOT). Truckers – State of Michigan MDOT also issues press releases when major regional changes take effect.
For local roads, check the website of the county road commission or city public works department along your route. Michigan law requires every authority that imposes seasonal restrictions to post the affected roads and the dates restrictions are in effect on its website, or through a statewide road association if it doesn’t maintain its own site.1Michigan Legislature. MCL 257-722 One more point worth knowing: routes designated as “all-season” on the Truck Operators Map (shown in green and gold) carry no reduced axle weights at any point in the spring, so a load that stays on those roads isn’t waiting on an end date at all.3Michigan Department of Transportation (MDOT). Annual Spring Weight Restrictions Changing Monday, March 9 Before dispatching during the March-through-May window, checking both the state bulletin and the local authority for every segment of your route is the only way to know for certain whether restrictions have been lifted.