Climate zones
The International Energy Conservation Code splits the US into eight temperature zones and three moisture regimes (A moist, B dry, C marine). Your zone sets the insulation the code asks for and much of what your house needs each season.
South Florida, Hawaii and the territories: almost no heating season and year-round humidity.
12 countiesZone2AHot-humidThe Gulf Coast and most of Florida: long, humid cooling seasons and brief cold snaps.
239 countiesZone2BHot-dryThe low deserts of Arizona and California: extreme summer heat with dry air.
20 countiesZone3AWarm-humidThe Southeast from Texas to the Carolinas: hot humid summers and mild winters with some freezes.
637 countiesZone3BWarm-dryInland California, southern Nevada, west Texas and New Mexico lowlands: dry heat and cool winters.
110 countiesZone3CWarm-marineCoastal California: mild year round, with marine moisture.
14 countiesZone4AMixed-humidThe mid-Atlantic and Ohio Valley belt: both a real heating season and a humid cooling season.
717 countiesZone4BMixed-dryHigh desert of New Mexico and Arizona: dry air with cold winter nights.
66 countiesZone4CMixed-marineWestern Oregon and Washington lowlands: cool, wet winters and mild summers.
34 countiesZone5ACool-humidThe Great Lakes, the lower Midwest and much of New England and New York: cold winters and humid summers.
638 countiesZone5BCool-dryThe Front Range, Great Basin and inland Northwest: cold winters, dry air and big daily swings.
146 countiesZone6ACold-humidThe upper Midwest and northern New England: long heating seasons.
306 countiesZone6BCold-dryThe northern Rockies and high plains: long, dry, cold winters.
119 countiesZone7Very coldNorthern Minnesota and Wisconsin, the high Rockies and parts of Alaska.
68 countiesZone8SubarcticInterior and northern Alaska.
7 counties