2021 New Hampshire winter frost/spring thaw laws and seasonal weight restrictions.
The maximum allowable vehicular weight posted sections of State highways is 30,000 pounds gross weight, or the cumulative width in inches of all tires contacting the road surface multiplied by 300, whichever is less.
trucks carrying home heating oil, processed milk products, maple sap, and septic pumper trucks are exempted from seasonal bans with the approval of NHDOT District Engineers.
Over weight restrictions.
You can view which current roads are effected by spring thaw weight restrictions: https://nhdotpermits.org/SpringThawRestrictionsViewer.aspx
Here is a handy tool used to determine frost and thaw conditions:
We are currently not aware of any oversize restrictions during the spring thaw months. However this does not mean certain routes may not have oversize restrictions imposed. Be sure to contact the New Hampshire DOT during the winter months for more information; 603-227-4110