Approximate Range of Average Annual Minimum Temperatures for Each Zone Zone 1   Below -50 Zone 2   -50 to -40 Zone 3   -40 to -30 Zone 4   -30 to -20 Zone 5   -20 to -10 Zone 6   -10 to 0 Zone 7    0 to 10 Zone 8   10 to 20 Zone 9   20 to 30 Zone 10   30 to 40