Monthly Summary 



December, 19.S1 



Normal 



Extremes 



Barometer 



(Readings reduced to sea level) 



Maximum 30.63, 8th 



Minimum 29.55,14th 



Mean semi-daily 30.058 



Range 1.08 



Air Temperafure 



Highest 56.12th 



Lowest 9, 21st 



Mean 31.6 



Monthly range 47 



Highest mean daily 45.5, 12th 



Lowest mean daily 23.0, 27th 



Mean maximum 40.0 



Mean minimum 24.6 



Greatest daily range 28, 29th 



Least daily range 4, 4th 



Precipitation 



Precipitation. In inches 3.83 



Snow, in inches 3.25 



Maximum precipitation in 24 hrs. 1.04, 



22nd, 23rd 

 Number of days on which .01 or 



more inches of rain fell 10 



Wind (miles) 



Total movement 5,141 



Greatest daily movement 445, 15th 



Least daily movement 39, 9th 



Mean hourly velocity 7.0 



Maximum velocity for 5 min. ... 40, 7th 



(correcced to conform to .s cup anemometer) 



Wind (direction) 



Prevailing direction nw 



North, days 3 



Northeast, days 



East, days 



Southeast, days 2 



South, days 5 



Southwest, days 



West, days 4 



Northwest, days 17 



Weather 



Mean relative humidity, per cent . . 63.0 



Mean cloudiness, per cent 52 



Number of clear days 10 



Number of fair days 4 



Number of cloudy days 17 



Number of hours bright sunshine 112.7 

 Percent of possible hours of bright 



sunshine 39 



Thunder and lightning ... 23rd 



30.65 



29.25 



30.056 



1.40 



54.5 

 -2.3 

 27.3 

 56.8 



3.47 

 8.99 



9 



4,726 



6.4 

 29 



77.2 

 53.4 

 8 

 10 

 13 

 130.7 



46 



30.96, 1889 

 28.85, 1915 



1.78, 1895; 1.01, 1892 



65.5, 1908 

 -22.5, 1917 



7.77, 1901 ; 0.87, 1896 

 26.50, '01, '02; t, 1891 



17, 1902; 4, 1892 

 6,694, 1925; 3,239, 1918 



41, 1928 



87.1, 1919; 67.2, 1890 



68, 1897; 39, 1919 



15, 1890; 2, 1922 



16, 1909; 4, 1889, 1930 



19, 1911, 1922; 7, 1909, 1923 



172, 1896; 86, 1922 



Note— The first column in the above summary gives observations made durinff tlie 

 month. The second column erives averay:es based on observations made from 1*89 to 

 192s. The third column gives extremes observed from 1889 to I'.iHO. 



