WEATHER TRAITS
West
Aridity, drying winds, great temperature extremes, and sudden changes. The west boundary borders the foothills of the Rockies, and there are some important mountain ranges within the area, Gardening there is modified by altitude.
Hardiness is a problem with many plants. More than half the winter days are sunny. Sunlight is intense. There are 140 to 200 (average) clear days per year. Annual rainfall is about 15” to 22” inches; some sections get as little as 10” inches, summer droughts are common. Frost-free days range from about 90 in the north to 190 in the south. Soils are often alkaline.
North
Snow covers most of the winter in northern parts; snow cover is not dependable in the south of the area. The growing season lasts about five months, (In the north of the area it is a month shorter than in the south of the area.) Summer’s caolóaverage hottest day is about 100 degrees and much cooler in the northern parts.
The yearly mean temperature is about 46. Fairly humidórainfall averages 20” to 30” inches per year. Winters are cold with 20” to 70” inches of snow. Frost often penetrates 30” inches or more. In Dakotas, the climate is more fluctuating and hotter in summer. The average lowest temperature is 30 degrees.
East
Humid rainfall averages 35” to 41” inches per year. Medium-length growing season (six to seven months). Average of 100 to 140 clear days per year. The yearly mean temperature is about 53 degrees.
Annual snowfall is 20” to 50” inches in the north, but less in the south of the region. There are 40 to 50 thunderstorms per year (Ohio). The average July temperature is about 74 degrees, and the average January temperature is about 29 degrees.
Heart
Intermediate between West and East in rainfall-34 inches yearly average. Growing season is 51,12 to 6’/2 months, or 160 to 180 days (intermediate between north and south). The winter average cold temperature is about 10 degrees below zero.
Hot summers average hottest day is about 100 degrees, and the average July temperature is 75 to 80 degrees. The yearly average temperature is about 55 degrees.
South West
This is an area of drying winds, As one goes west in it there is less rainfall and greater temperature extremes. The rainfall range is from about 12” inches per year in the west to 36 in the east.
Average January temperatures in the region range from 32 to 48; average July temperatures from 78 to 84. Frost-free clays range from 180 to 230. The climate here is characterized by rapid changes, great extremes, and diversity, open winters.
Mid-South
Without extending entirely to Gulf Coastal districts, our Mid-South area takes in the warmer, moister latitudes that are influenced by the nearness of the Gulf and also at times by sterner climates of the interior. Summer and winter humidity is rather high. There is considerable winter rainfall.
Snow is infrequent and of slight depth, and frost seldom penetrates more than one to three inches into the soil, Average January temperatures over the area range from 36 to 50; average July temperatures from 78 to 82; annual rainfall ranges from about 42” to 52” inches; and the season without frost from 6Y.T to eight months.
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