26 MISC. PUBLICATION 303, U. S. DEPT. OF AGRICULTURE 



REGION 25, OZARK-OHIO-TENNES8EE BIVER VALLEYS 



Humid, mesothermal, with adequate precipitation at all seasons. 

 In the extreme southwestern portion subhumid. Much alternates 

 freezing and thawing in winter. 



Average annual number of days with snow cover, 10 to 30 in the. 

 north, 1 to 10 in the south. Average annual frost-free season 160 

 days in the north to 200 in the southeast and 240 in the southwest. 



REGION 26, NOBTHEBN GREAT LAKES-ST. LAWRENCE 



Humid, microthermal, with adequate precipitation at all seasons. 

 There are two local portions in northern and southern New York 

 that are wet rather than humid. 



Average annual number of days with snow cover, 90 to 120 in the 

 southern portions to more than 120 northward. Average annual 

 growing season less than 100 days in the north and at higher eleva- 

 tions to about 130 in the south. 



REGION 27, APPALACHIAN 



Northern portion humid, microthermal; southwestern and south- 

 central portions humid, mesothermal. Local areas of wet micro- 

 thermal climates are distributed along the backbone of the mountains, 

 and there is a wet mesothermal area in the southeastern portion. 



Average annual number of days with snow cover 1 to 10 in the 

 extreme southern portion to as much as 90 in the extreme north. In 

 the central portion 30 to 60 days is commonest. Average annual 

 frost-free season 130 days in the north, especially at higher eleva- 

 tions, to 210 days in the extreme southern portion. Throughout, the 

 season is shorter with increasing altitude. 



REGION 28, PIEDMONT 



Generally humid, mesothermal, but microthermal in the extreme 

 northern portion, with adequate precipitation at all seasons. Warmer 

 than region 27. 



Average annual number of days with snow cover 1 to 10, decreasing 

 southward to less than 1, increasing northward from 10 to 30. Aver- 

 age annual growing season from 170 days in the north to 220 or 

 more in the south, longer coastward. 



REGION 29, UPPER COASTAL PLAIN 



Humid, mesothermal, rainfall adequate at all seasons. Average 

 annual number of days with snow cover less than 1 in the southern 

 half, 1 to 10 in the northern half. Growing season 200 days in the 

 north to 260 days in the south, longer coastward. 



REGION 30, SWAMPY COASTAL PLAIN 



Humid, mesothermal, with adequate precipitation at all seasons 

 except in the extreme west where it gradually diminishes to a de- 

 ficiency at all seasons. In central Florida the climate is subhumid, 

 rather than humid. 



