SEVENTEENTH ANNUAL YEAR BOOK— PART X 535 



AUGUST. 



The month was marked by a continuance, but in a modified degree, 

 of the hot, dry weather that featured July. The temperature averaged 

 above the normal until the 22d, except during the 5-day period beginning 

 on the 11th. Most of the last decade was cooler than usual, with light 

 frosts reported from a few northern stations on the 27th and 28th. 



The state received about 70 per cent of the normal August precipita- 

 tion, and much the greater part of this came during the first half of the 

 month. The rains broke the severe drought in most districts and were 

 of inestimable value to all growing crops, but especially to corn. In some 

 sections, however, that crop had already been seriously damaged by the 

 dry weather. After the 15th but little rain fell in any part of the state 

 until the last day of the month, with the result that the ground became 

 too dry for plowing. 



A 'severe wind and electrical storm occurred at Sioux City on the 6th. 

 The total loss in the city was estimated at $100,000. For one minute the 

 wind blew at the rate of 120 miles an hour, which is the highest velocity 

 on record at that station for a similar length of time. 



An auroral display of marked brilliancy occurred on the night of the 

 26th-27th; a brief description of the phenomenon appears under the 

 heading "Miscellaneous Phenomena." 



Pressure. — The mean pressure (reduced to isea level) for the state 

 was 29.98 inches. The highest recorded was 30.34 inches, at Charles City, 

 on the 13th, and the lowest was 29.54, at Sioux City, on the 10th. The 

 monthly range was 0.80 of an inch. 



Temperature. — The mean temperature for the state, as shown by the 

 records of 106 station®, was 74.0% or 2.2° higher than the normal. By 

 divisions, three tiers of counties to the division, the means were as follows: 

 Northern, 72.3°, or 1.9° higher than the normal; Central, 74.0°, or 2.3° 

 higher than the normal; Southern, 75.6°, or 2.4° higher than the normal. 

 The highest monthly mean (only complete records considered) was 77.5°, 

 at Keokuk, and the lowest was 69.7', at Sibley. The highest temperature 

 reported was 105°, at Webster City, on the 4th, and the lowest was 35°, 

 at Matlock, on the 27th. The temperature range fdr the state was 71°. 



Precipitation.— The average precipitation for the state, as shown by 

 the records of 116 stations, was 2.58 inches, or 1.10 inches less than the 

 normal. By divisions the averages were as follows: Northern, 2.01 

 inches or 1.47 inches less than the normal; Central, 2.77 inches, or 1.00 

 inch less than the normal; Southern, 2.96 inches, or 0.82 of an inch 

 less than the normal. The greatest amount, 6.23 inches, occurred at 

 Thurman, and the least, 0.49 of an inch, at Delaware. The greatest 

 amount in 24 consecutive hour®, 3.21 inches, occurred at Bloomfield, on 

 the lOth-llth. 



Humidity — The average relative huimidity for the state at 7 a. m. was 

 79 per cent, and at 7 p. m. it was 58 per cent. The mean for the month 

 was 69 per cent, or 2 per cent lower than the normal. The highest monthly 

 mean was 73 per cent, at Charles City and Keokuk, and the lowest was 

 65 per cent, at Davenport and Des Moines. 



