ZONE 31. Interior Plains of Gulf Coast and Coastal Southeast
Growing season: mid-Mar. to early Nov. In this extensive east-west zone, hot and sticky summers contrast with chilly winters (record low temperatures are 7 degrees to 0 degrees F/-14 degrees to -18 degrees C). There's rain all year (an annual average of 50"), with the least falling in Oct.
ZONE 32. Interior Plains of Mid-Atlantic States; Chesapeake Bay, Southeastern Pennsylvania, Southern New Jersey
Growing season: late Mar. to early Nov. Rain falls year-round (40" to 50" annually); winter lows (moving through the zone from south to north) are 30 degrees to 20 degrees F/-1 degree to -7 degrees C. Humidity is less oppressive here than in Zone 31.
ZONE 34. Lowlands and Coast from Gettysburg to North of Boston
Growing season: late April to late Oct. Ample rainfall and humid summers are the norm. Winters are variable ― typically fairly mild (around 20 degrees F/-7 degrees C), but with lows down to -3 degrees to -22 degrees F/-19 degrees to -30 degrees C if arctic air swoops in.
ZONE 36. Appalachian Mountains
Growing season: May to late Oct. Thanks to greater elevation, summers are cooler and less humid, winters colder (0 degrees to -20 degrees F/-18 degrees to -29 degrees C) than in adjacent, lower zones. Rain comes all year (heaviest in spring). Late frosts are common.
ZONE 37. Hudson Valley and Appalachian Plateau
Growing season: May to mid-Oct., with rainfall throughout. Lower in elevation than neighboring Zone 42, with warmer winters: lows are 0 degrees to -5 degrees F/-18 degrees to -21 degrees C, unless arctic air moves in. Summer is warm to hot, humid.
ZONE 39. Shoreline Regions of the Great Lakes
Growing season: early May to early Oct. Springs and summers are cooler here, autumns milder than in areas farther from the lakes. Southeast lakeshores get the heaviest snowfalls. Lows reach 0 degrees to -10 degrees F/-18 degrees to -23 degrees C.
ZONE 40. Inland Plains of Lake Erie and Lake Ontario
Growing season: mid-May to mid-Sept., with rainy, warm, variably humid weather. The lakes help moderate winter lows; temperatures typically range from -10 degrees to -20 degrees F/-23 degrees to -29 degrees C, with occasional colder readings when arctic fronts rush through.
ZONE 42. Interior Pennsylvania and New York; St. Lawrence Valley
Growing season: late May to late Sept. This zone's elevation gives it colder winters than surrounding zones: lows range from -20 degrees to -40 degrees F/-29 degrees to -40 degrees C, with the colder readings coming in zone's Canadian portion. Summers are humid, rainy.