SOS TOWA DEPARTMENT OF ACUICTIT.TUUE 



SEPTEMBER. 



September, 1913, will go on record as having the hottest weeli of any 

 September on record, and with one exception the earliest general killing 

 frost and freezing temperatures. The first seven, days of the month were 

 excessively hot; the daily maximum temperatures being 100° or higher 

 every day over the southern and considerably above 90° in the northern 

 counties. After the 7Ui the temperature was generally below the normal 

 with light frost over the northern counties on the 13th, and a killing 

 frost and freezing temperatures in all parts of the State on the 22d. In 

 1890 killing frost was quite general over the State on September 13th, 

 the earliest on record since the establishment of the Weather Service. 



The first week of the month was also excessively dry, there being only 

 a few light and widely scattered showers, but after the 7th showers 

 were frequent and fairly well distributed so the average monthly amount 

 was only 0.10 inch below the normal. 



The hot, dry weather early in the month forced corn to maturity pre- 

 maturely, but it caused the crop to escape the more serious damage of 

 the killing frost and freezing temperatures on the 22d. The frost was 

 general and freezing temperatures occurred in practically all parts of 

 the State, but the <bulk of the corn crop was far enough advanced to 

 escape injury, and the small percentage that did not was damaged but 

 slightly. The rains during the second and third decades of the month 

 revived pasturage, replenished the water supply and put the ground in 

 excellent condition for fall plowing and seeding, and much of that work 

 was done. 



Tempebatuke. — The monthly mean temperature for the State, as shown 

 by the records of 109 stations, was 64.5°, or 0.8° higher than the normal 

 for Iowa. By sections the 'mean temperatures were as follows: North- 

 ern, 62.8°, or 0.7° higher than the normal; Central, 64.4°, or 0'.8 higher 

 than the normal; Southern, 66.2°, or 0.7° higher than the normal. The 

 highest monthly mean was 67.9°, at Onawa, ;Monona County; and the 

 lowest monthly mean, 60.6°, at Elma, Howard County. The highest tem- 

 perature reported was 107°, at Bedford, Taylor County, on the 5th; the 

 lowest temperature reported was 19°, at Rock Rapids, Lyon County, on 

 the 22d. The average monthly maximum was 100°, and the average 

 monthly minimum was 27°. The greatest daily range was 53°, at Bloom- 

 field, Davis County. The average of the greatest daily ranges was 38". 



Pkecipitation. — The average precipitation for the State, as shown by 

 the records of 117 stations, was 3.31 Inches, or 0.10 inch less than the 

 normal. By sections the averages were as follows: Northern, 3.35 inches, 

 or 0.06 inch less than the normal; Central, 3.57 inches, or 0.33 inch greater 

 than the normal; Southern, 3.01 inches, or 0.56 inch less than the normal. 

 The greatest amount, 7.44 inches, occurred at Clarinda, Page County, and 

 the least, 0.45 inch, at Rock Rapids, Lyon County. The greatest amount 

 in any 24 consecutive hours, 3.90 inches, occurred at Clarinda, Page 

 County, on the 10th and 11th. Measurable precipitation occurred on an 

 average of 9 days. 



Sunshine and Cloudiness. — The average number of clear days was 15; 

 partly cloudy, 8; cloudy, 7. The duration of sunshine was slightly above 



