Québec has three thaw zones, in which the start and end of the load restriction periods are slightly lagged over time. This division of Québec’s territory into three zones was established by accounting for the geographical realities, the usual frost depth and the thaw trends in the different regions, the spring weather conditions and the traffic of heavy vehicles in the east-west axis.

Zone 1 includes the Québec territory located south of the following demarcation line, hereinafter referred to as the "demarcation line between zones 1 and 2.
From the intersection point of the centre line of the Ottawa River (Québec-Ontario border):

with the extension of the centre line of rivière Schyan in Municipalité de Sheenboro;

Thence, easterly, a straight line to the intersection of rivière Picanoc and route 105 in Ville de Gracefield;

Thence, easterly, a straight line to the intersection of autoroute 15 and route 329 in Ville de Sainte-Agathe-des-Monts;

Thence, northeasterly, a straight line to the intersection of route 155 and route 159 in Municipalité de la paroisse de Saint-Roch-de-Mékinac to its intersection with the northeastern limit of Municipalité de Mandeville;

Thence, southeasterly, following the northeastern limit of Municipalité de Mandeville to its intersection with the northwestern limit of Municipalité de la paroisse de Saint-Alexis-des-Monts;

Thence, northeasterly, a straight line to the intersection of the southwestern limit of Municipalité de Rivière-à-Pierre and the northwestern limit of Municipalité de Notre-Dame-de-Montauban;

Thence, northeasterly, the extension of the latter line to its intersection with the southwestern limit of the Portneuf Wildlife Sanctuary;

Thence, in a general easterly direction, following the perimeter of the Portneuf Wildlife Sanctuary counterclockwise to its intersection with the northwestern limit of Ville de Saint-Raymond;

Thence, northeasterly, then southeasterly and northeasterly, following the northwestern and northeastern limits of Ville de Saint-Raymond and then the northwestern limit of Municipalité de Saint-Gabriel-de-Valcartier to its intersection with the southwestern limit of the Laurentides Wildlife Sanctuary;

Thence, southeasterly, then in a general northeasterly direction, following the perimeter of the Laurentides Wildlife Sanctuary counterclockwise to its intersection with the western limit of the Jacques-Cartier Conservation Park;

Thence, in general southeasterly, northeasterly and southeasterly directions, following the perimeter of the Jacques-Cartier Conservation Park counterclockwise to its intersection with the southwestern limit of the Laurentides Wildlife Sanctuary;

Thence, southeasterly, along the southwestern limit of the Laurentides Wildlife Sanctuary to its intersection with the southeastern limit of the route 175 right-of-way;

Thence, southeasterly, a straight line to the intersection of route 138 with the northeastern limit of Ville de Beaupré;

Thence, southeasterly, the extension of the latter line to its intersection with the centre line of the arm of the St. Lawrence River located north of Île d’Orléans;

Thence, in a general northeasterly direction, successively following the centre line of the said northern arm of the St. Lawrence River, the centre line of the river to the northeastern limit of Municipalité de la paroisse de Saint-Germain and then a straight line to the southwestern tip of Île aux Lièvres;

Thence, northeasterly, a straight line to the intersection of autoroute 20 with the northeastern limit of Ville de Rivière-du-Loup;

Thence, in a general southerly direction, following the perimeter of Ville de Rivière-du-Loup clockwise to its intersection with the northeastern limit of the route 185 right-of-way;

Thence, in a general southeasterly direction, following the generally northeastern limit of the route 185 right-of-way to its intersection with the New Brunswick border.

Zone 2 includes Îles-de-la-Madeleine and the Québec territory contained between the "demarcation line between zones 1 and 2" heretofore described and the following line, hereinafter referred to as the "demarcation line between zones 2 and 3".

From the intersection point of the parallel of latitude 48° 00’ north and the Ontario border:

Thence, southeasterly, a straight line to the intersection of route 101 and the southern limit of Ville de Rouyn-Noranda;

Thence, easterly, a straight line to the Rapide-Sept hydroelectric dam;

Thence, easterly, a straight line to the intersection of route 117 with the northern limit of the La Vérendrye Wildlife Sanctuary;

Thence, easterly, a straight line to the intersection of route 167 with the southern limit of the Ashuapmushuan Wildlife Sanctuary;

Thence, in a general northwesterly direction, following the perimeter of the Ashuapmushuan Wildlife Sanctuary counterclockwise to its intersection with the northwestern limit of Municipalité de Saint-Thomas-Didyme;

Thence, northeasterly, following the northwestern, southwestern, northern and northeastern limits of Municipalité de Saint-Thomas-Didyme, and then successively the generally northwestern limits of Municipalité de Saint-Edmond-les-Plaines, Municipalité de Girardville and Municipalité de Notre-Dame-de-Lorette to its intersection with the northeastern limit of Municipalité de Notre-Dame-de-Lorette;

Thence, easterly, a straight line to the Manic-3 hydroelectric dam;

Thence, northeasterly, a straight line to a point located on the parallel of latitude 51° 00’ north, 60 meters east of the bank of Lac Caron (intersection of the northern and western limits of the Port-Cartier–Sept-Îles Wildlife Sanctuary);

Thence, easterly, along the parallel of latitude 51° 00’ north, to a point located 60 metres east of the rivière Sainte-Marguerite (intersection of the northern and eastern limits of the said sanctuary);

Thence, easterly, a straight line to the intersection of the parallel of latitude 52° 00’ north with the eastern limit of the province of Québec, north of Municipalité de Blanc Sablon.

Zone 3 includes the Québec territory located north of the "demarcation line between zones 2 and 3" heretofore described.