MONTHLY SUMMARY 



December 1939 



Barometer, in inches 



(Readings reduced to sea level) 



Maximum 30.45, 15th 



Minimum 29.27, 7th. 8th 



Mean semi-daily 29.831 



Range 1.18 



Air Temperature, in degrees F. 



Highest 53, 1st, 2nd, 3rd 



Lowest 1, 27th 



Mean 28.9 



Range 52 



Highest mean daily 46.5, 3rd 



Lowest mean daily 10.0, 27th 



Mean maximum 37. 1 



Mean minimum 20.7 



Greatest daily range 34, 1st 



Least daily range 6, 20th 



Precipitation, in inches 



Precipitation 3.89 



Snow 4.75 



Max. precipitation in 24 hrs. . . 1 48, 2nd, 3rd 

 Number of days with 01 or more 9 



Wind, in miles 



Total movement 5519 



Greatest daily movement 473, 8th 



Least daily movement 35. 2nd 



Mean hourly velocity 7 4 



Maximum velocity 39, 8th, 23rd 



Wind, direction 



Prevailing direction WNW 



North, days 5 



Northeast, days 



East, days 



Southeast, days 1 



South, days 6 



Southwest, days 2 



West , days 5 



Northwest, days 12 



Weather 



Mean relative humidity, percent 75.3 



Mean cloudiness, percent 56 



Number of clear days 7 



Number of fair days 6 



Number of cloudy days 1 



Number hours bright sunshine 100 



Percent of possible hours of bright 



sunshine 35.3 



Normal 



Extremes 



30.66 



29.27 



30.06 



1.38 



54.3 

 -19 

 27.5 

 56.2 



3.39 

 8.50 



10 



4710 



6.3 

 31.4 



WNW 



69.4 

 54.9 



8 



9 



14 



128 



45.2 



30.96, 1889 

 28 85, 1915 



1.78, 1895; 1.01, 1892 



65.5, 1908 



- 22.5, 1917 



36.9, 1891; 17.1, 1917 



7.77, 1901; .87, 1896 

 26.50, '02; t, 1891 



17, 1902; 4, 1892 



6,694, 1925; 3,239, 1918 



48, 1938 



71, 1929; 39, 1919 



15, 1890; 2, 1922,1933 



16,'09;4,'89,'30,'31,'36,'38 



'23, '33; 7, '09, '23 



172, 1896; 63, 1933 



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

 month. The second column gives the averages based on observations made from 

 1889 to 1938, except that humidity records are based on observations made from 

 1929 to 1938. The third column gives extremes observed from 1889 to 1938. 



