SOIL SURVEY OF WRIGHT COUNTY, IOWA. 11 



CLniATE, 



The climate of Wright County shows wide variation in tempera- 

 ture, the difference in extremes being 140° F. It is nevertlieless 

 healthful and suitable for the growing of staple crops common to 

 this region. 



The mean annual precipitation is 32.36 inches. The greatest an- 

 nual rainfall, 42.58 inches, occurred in 1918, while the least, 20.38 

 inches, fell in 1910. The rainfall is generally well distributed 

 through the growing season, about 73 per cent falling from April 

 to September, inclusive. The rain usually falls slowly and gently. 

 Occasionally convectional storms, some accompanied by hail, cause 

 considerable damage in narrow belts of country. 



Owing to the high moisture-holding capacity of most of the soils, 

 the periods of drought that sometimes occur during the growing 

 season have never caused a crop failure. How^ever, crops on the 

 sandy ridges and gravelly-subsoil terraces suffer considerably dur- 

 ing such periods. Excessive rainfall is more apt to be injurious to 

 the crops than drought. 



The mean temperature of the summer is 70.5° F., the highest tem- 

 perature on record being 103° F. Periods of excessive heat are 

 generally of very short duration. Prevailing summer wdnds are 

 from the south and southwest. Strong winds are common, but 

 tornadoes are of very rare occurrence. 



The winters are usually quite cold, the temperature averaging 

 r7,5° F. Heavy snows are of usual occurrence, the average annual 

 snowfall amounting to about 2 feet. Frequently the drifting snow 

 causes mucli trouble by blockading roads and railroads. 



Clover and wdieat arc not infrequently injured by wnnter killing. 

 The winds in the wnnter generally come from the northwest, and 

 nearly every farmstead has a windbreak of trees on that side for 

 protection. Narrow, broken belts of timber along the rivers and 

 creeks afford the only natural protection in the county. 



The earliest recorded killing frost in the fall occurred on Septem- 

 ber 17, and the latest in the spring, on May 17. The average date 

 of the first killing frost in the fall, however, is October 5, and the 

 average date for the last in the spring is May 6. This gives an 

 average growing season of 152 days. 



The heavy prairie soils, because of their moisture-holding capacity, 

 arc rather slow in warming up in the spring, and early-maturing 

 varieties of corn should be planted to avoid injury by fall frosts. 

 On the lower lying lands especially, even where the drainage is well 

 established, it is important to grow the earlier maturing varieties 

 of corn to insure a normal crop. 



