USDA Hardiness Zone 4b

4 town pages in this zone so far.

Zone 4b on the 2023 USDA Plant Hardiness Zone Map means an average annual extreme minimum temperature of -25°F to -20°F, averaged over 1991 to 2020. The zone is about the coldest winter night, not frost dates or summer heat, so towns in the same zone can have different frost dates.

Towns in zone 4b

RochesterZone 4b, median last frost Apr 30
DuluthZone 4b, median last frost May 6
HelenaZone 4b, median last frost May 9
Eau ClaireZone 4b, median last frost May 8

Source: USDA Plant Hardiness Zone Map 2023, USDA-ARS and PRISM Group, Oregon State University. Zone of each town at its center point.