Zones 2-10 in the map have been subdivided into light- and dark-colored sections (a and b) that represent 5 F (2.8 C) differences within the 10 F (5.6 C) zone. The light color of each zone represents the colder section; the dark color, the warmer section. Zone 11 represents any area where the average annual minimum temperature is above 40 F (4.4 C). The map shows 20 latitude and longitude lines. Areas above an arbitrary elevation are traditionally considered unsuitable for plant cropping and do not bear appropriate zone designations. There are also island zones that, because of elevation differences, are warmer or cooler than the surrounding areas and are given a different zone designation. Note that many large urban areas carry a warmer zone designation than the surrounding countryside. The map-contains as much detail as possible, considering the vast amount of data on which it is based and its size

USDA Hardiness Zones & Average Annual Minimum Temperature Range

Fahrenheit Celsius Example Cities 1 Below -50 F Below -45.6 C Fairbanks, Alaska; Resolute, Northwest Territories (Canada) 2a -50 to -45 F -42.8 to -45.5 C Prudhoe Bay, Alaska; Flin Flon, Manitoba (Canada) 2b -45 to -40 F -40.0 to -42.7 C Unalakleet, Alaska; Pinecreek, Minnesota 3a -40 to -35 F -37.3 to -39.9 C International Falls, Minnesota; St. Michael, Alaska 3b -35 to -30 F -34.5 to -37.2 C Tomahawk, Wisconsin; Sidney, Montana 4a -30 to -25 F -31.7 to -34.4 C Minneapolis/St.Paul, Minnesota; Lewistown, Montana 4b -25 to -20 F -28.9 to -31.6 C Northwood, Iowa; Nebraska 5a -20 to -15 F -26.2 to -28.8 C Des Moines, Iowa; Illinois 5b -15 to -10 F -23.4 to -26.1 C Columbia, Missouri; Mansfield, Pennsylvania 6a -10 to -5 F -20.6 to -23.3 C St. Louis, Missouri; Lebanon, Pennsylvania 6b -5 to 0 F -17.8 to -20.5 C McMinnville, Tennessee; Branson, Missouri 7a 0 to 5 F -15.0 to -17.7 C Oklahoma City, Oklahoma; South Boston, Virginia 7b 5 to 10 F -12.3 to -14.9 C Little Rock, Arkansas; Griffin, Georgia 8a 10 to 15 F -9.5 to -12.2 C Tifton, Georgia; Dallas, Texas 8b 15 to 20 F -6.7 to -9.4 C Austin, Texas; Gainesville, Florida 9a 20 to 25 F -3.9 to -6.6 C Houston, Texas; St. Augustine, Florida 9b 25 to 30 F -1.2 to -3.8 C Brownsville, Texas; Fort Pierce, Florida 10a 30 to 35 F 1.6 to -1.1 C Naples, Florida; Victorville, California 10b 35 to 40 F 4.4 to 1.7 C Miami, Florida; Coral Gables, Florida 11 above 40 F above 4.5 C Honolulu, Hawaii; Mazatlan, Mexico