FIFTEENTH ANNUAL YEAR BOOK— PART XI 775 



All fall sown grains, grass and alfalfa were well protected by a thick 

 mantle of snow during the periods of low temperature. Sleighing was 

 excellent over the greater part of the state after the 18th. 



Pressure. — The mean sea level pressure for the state was 30.25 inches. 

 The highest recorded was 30.72 inches, at Keokuk on the 16th, and the 

 lowest was 29.53 inches, at Davenport and Keokuk, on the 29th. 



Temperature. — The monthly mean for the state, 109 stations reporting, 

 was 15.7°, or 8.2° below the normal, and with one exception was the coldest 

 December of record. By sections, the mean temperatures were as follows: 

 Northern, 12.7°, or 8.5° below the normal; Central, 16.2°, or 7.9° below 

 the normal; Southern, 18.2°, or 8.2° below the normal. The highest tem- 

 perature reported in the state was 63° at Bloomfleld, on the 1st, and the 

 lowest was — 31° at Iowa Falls, on the 26th. The temperature averaged 

 lower, and lower readings were recorded, over the eastern and north- 

 eastern counties than over the western and southwestern counties. At 

 Iowa City, the 26th, with a temperature of — 22°, was the coldest Decem- 

 ber day recorded since December 31, 1863, when the temperature was 23° 

 below zero. 



Humidity. — The mean relative humidity for the state at 7 a. m. was 

 87 per cent, and at 7 p. m. it was 83 per cent. The mean for the month 

 was 85 per cent, or 6 per cent more than the normal. The highest monthly 

 mean was 90 per cent at Charles City, and the lowest 82 per cent at 

 Des Moines, Dubuque and Keokuk. The high percentage of humidity at 

 the 7 p. m. observations, as compared with the average for 7 a. m., is 

 remarkable. 



Precipitation. — The average for the state, 116 stations reporting, was 

 1.30 inches, or 0.08 inch more than the normal. By sections the averages 

 were as follows: Northern, 1.09 inches, or 0.02 inch more than the 

 normal; Central, 1.43 inches, or 0.18 inch more than the normal; Southern, 

 1.38 inches, or 0.03 inch more than the normal. The greatest amount re- 

 ported from any station was 2.24 inches, at Tipton, and the least, 0.57 

 inch, at Le Mars. The greatest amount in any 24 consecutive hours, 1.03 

 inches, occurred at Washington, on the 28th-29th. All of the precipitation 

 after the 7th came in the form of snow, and, while the amounts were not 

 great, the flurries were frequent. The average number of days with 0.01 

 inch or more of precipitation was 9, which is 4 more than the average for 

 December, and has not been equalled or exceeded in any December of 

 record, except in 1909, when there were 11 days. 



Snowfall. — The average for the state was 11.1 inches, or almost twice 

 the normal amount. The greatest monthly amount was 20.2 inches at 

 Waterloo, and the least 5.2 inches at New Hampton. 



Wind. — The prevailing direction of the wind was from the northwest. 

 The highest velocity was at the rate of 40 miles an hour from the north- 

 west, at Sioux City, on the 29th. 



Sunshine and Cloudiness. — The average percentage of the possible 

 amouat of sunshine was 39 per cent, or about 10 per cent less than the 

 normal. The average number of clear days was 10; partly cloudy, 6; 

 cloudy, 15. 



