Zone 1 |below -50 F
Zone 1 has a low temperature of below -50 Fahrenheit and below -45.6 Celsius, covering interior areas of Alaska, Resolute, Northwest Territories of Canada, northernmost tip of China.
Zone 2a |-50 to -45 F
Zone 2a has a low temperature of -50 to -45 Fahrenheit and -42.8 to -45.5 Celsius, spanning from interior areas of Alaska, northern regions of Canada (Manitoba), and northernmost isolated parts of China.
Zone 2b |-45 to -40 F
Zone 2b has a low temperature of -45 to -40 Fahrenheit and -40 to -42.7 Celsius, spanning from interior areas of Alaska (Unalakleet), the northernmost tip of Minnesota, middle regions of Canada, and northernmost regions of China.
Zone 3a | -40 to -35 F
Zone 3a has a low temperature of -40 to -35 Fahrenheit and -37.3 to -39.9 Celsius, spanning from northernmost regions of Minnesota (International Falls), interior and northern coastal areas of Alaska (St. Michael), southern regions of Canada, northern regions of Europe, northern regions of China, and central regions of northern Japan.
Zone 3b | -35 to -30 F
Zone 3b has a low temperature of -35 to -30 Fahrenheit and -34.5 to -37.2 Celsius, spanning from northernmost regions of the US, interior and northern coastal areas of Alaska, southern regions of Canada, northern areas of Europe, some central and northern interior regions of China, and interior regions of northern Japan.
Zone 4a |-30 to -25 F
Zone 4a has a low temperature of -30 to -25 Fahrenheit and -31.7 to -34.4 Celsius, spanning from northern regions in the Midwest and northeast US, western coastal areas of Alaska, coastal regions of eastern Canada, northern areas of Europe, some central and northern interior regions of China, isolated areas of South America, and northern regions of Japan.
Zone 4b |-25 to -20 F
Zone 4b has a low temperature of -25 to -20 Fahrenheit and -28.9 to -31.6 Celsius, spanning from centrally located regions in the Midwest and northeast US, southern coastal areas of Alaska, coastal regions of eastern Canada, northern regions of Europe, some central and northern interior regions of China, southern regions of interior South America, and coastal regions of northern and interior regions of southern Japan.
Zone 5a |-20 to -15 F
Zone 5a has a low temperature of -20 to -15 Fahrenheit and -26.2 to -28.8 Celsius, spanning from central regions in the Midwest and lower regions of the northeast US, southern coastal areas of Alaska, coastal regions of western Canada, central interior regions of Europe, central and northern interior regions of China, southern interior regions of South America, and coastal regions of northern and interior regions of southern Japan.
Zone 5b |-15 to -10 F
Zone 5b has a low temperature of -15 to -10 Fahrenheit and -23.4 to -26.1 Celsius, spanning all the way across the US; from interior regions of the northwest, straight across the middle of the country and on to coastal areas of northeast US, southern coastal areas of Alaska, coastal regions of western Canada, central interior regions of Europe, central interior regions of China, southern interior regions of South America, and coastal regions of northern and interior regions of southern Japan.
Zone 6a |-10 to -5 F
Zone 6a has a low temperature of -10 to -5 Fahrenheit and -20.6 to -23.3 Celsius, spanning all the way across the US; from interior regions of the northwest to straight through the mid-US (St. Louis, Missouri) to southern Pennsylvania, southern coastal areas of Alaska, coastal regions of western Canada, central interior regions of Europe, central interior regions of China, southern regions of South America, and coastal regions of northern and interior regions of southern Japan.
Zone 6b |-5 to 0 F
Zone 6b has a low temperature of -5 to 0 Fahrenheit and -17.8 to -20.5 Celsius, spanning all the way across the US; from interior regions of the northwest across to northernmost areas of Tennessee on to the mid Atlantic coast, coastal regions of western Canada, central interior regions of Europe, central interior regions of China, southern regions of South America, and coastal regions of northern and central interior regions of southern Japan.
Zone 7a |0 to 5 F
Zone 7a has a low temperature of 0 to 5 Fahrenheit and -15 to -17.7 Celsius, spanning all the way across the US; from northeast California across southern Oklahoma to up through the Appalachian Mountains to the mid Atlantic coast, coastal regions of western Canada, central interior regions of China, central interior regions of Europe, coastal regions of northern and central interior regions of southern Japan, and northern and southern interior regions of Africa.
Zone 7b |5 to 10 F
Zone 7b has a low temperature of 5 to 10 Fahrenheit and -12.3 to -14.9 Celsius, spanning all the way across the US; from eastern California through southern New Mexico and central Texas, across the northern parts of Georgia and the Carolinas to the mid Atlantic coast, coastal regions of western Canada, central interior regions of Europe, central interior regions of China, coastal regions of northern and areas just inland in southern Japan, southern interior regions of South America, and northern and southern interior regions of Africa.
Zone 8a |10 to 15 F
Zone 8a has a low temperature of 10 to 15 Fahrenheit and -9.5 to -12 Celsius, spanning all the way across the US; from coastal areas of the northwest and California through central Arizona and Texas, across the southern halves and coasts of Mississippi, Alabama, Georgia and the Carolinas, central interior regions of Europe, central interior regions of China, coastal regions of southern Japan, southern interior regions of South America, and northern and southern interior regions of Africa.
Zone 8b |15 to 20 F
Zone 8b has a low temperature of 15 to 20 Fahrenheit and -6.7 to -9.4 Celsius, spanning all the way across the US; from coastal areas of the northwest and California through central Arizona and southern Texas, to across south Georgia and north Florida, the southern interior region of southeast Australia, southern interior regions of Europe, central interior regions of China, coastal and areas just inland in southern Japan, and northern and southern interior regions of Africa.
Zone 9a |20 to 25 F
Zone 9a has a low temperature of 20 to 25 Fahrenheit and -3.9 to -6.6 Celsius, covers areas of inland California and the Desert Southwest, southern Texas, and central Florida, southern regions of China, southern regions of Australia, coastal areas of southern Japan, and central regions to both the north and south of Africa.
Zone 9b |25 to 30 F
Zone 9b has a low temperature of 25 to 30 Fahrenheit and -1.2 to -3.8 Celsius, covers interior regions of California and the Desert Southwest, southernmost Texas, and central Florida, southern regions of China, southern regions of Europe, a band that crosses the middle of Australia, coastal areas of southern Japan, and regions of southern Mexico and South America.
Zone 10a |30 to 35 F
Zone 10a has a low temperature of 30 to 35 Fahrenheit and 1.6 to -1.1 Celsius, and covers areas of southernmost California and south Florida, southern regions of China, northern and southern coastal regions of Australia, southernmost coastal regions of Europe, interior and coastal regions of South America, and central and northern coastal regions of Africa.
Zone 10b |35 to 40 F
Zone 10b has a low temperature of 35 to 40 Fahrenheit and 4.4 to 1.7 Celsius, covers areas of south Florida (Miami), southern most coastal regions of Europe (Portugal, Spain, and Italy), southernmost regions of China, northern regions of Australia, central regions of South and Central America, and interior and coastal regions of Africa.
Zone 11 |above 40 F
Zone 11 has a low temperature of above 40 Fahrenheit and above 4.5 Celsius, covers Hawaii (Honolulu), Southern Mexico, the Florida Keys, the northern most region of Australia, southernmost regions of China, northern regions of South America, coastal regions of Central America, and central interior and coastal areas of Africa.
