MONTHLY SUMMARY 



December, 1941 



Noi-mal 



Extremes 



Barometer, in inches 



(Headings i-educed to sea level) 



Maximum 30.67, 12t!i 



Minimum 29.34, 24th 



Mean semi-daily 30.054 



Range 1 .3.") 



Air Temperature, in degrees F. 



Highest 56, 24(h 



Lowest 5, 21st 



Mean 31.1 



Range 51 



Highest mean daily -15, 24th 



Lowest mean daily 15, 2Ist 



Mean maximum 39.1 



Mean minimum 23.2 



Greatest daily range 30, 20tli 



Least daily range 7, 15th 



Precipitation, in inches 



Precipitation 3.S2 



Sno\y 2.00 



Maximum precipitation in 24 



hrs. 2.12, 13th, 14th 



Number of days with .01 or moi'e S 



Wind, in miles 



Total movement 5080 



Greatest daily movement 417, 7th 



Least daily movement 11, 3 1st 



Mean hourly velocity 6.8 



Maximum velocity 32, 6th, 20th 



Wind, direction 



Prevailing direction NW 



North, days 6 



Northeast, days 



East, days 



Southeast, days 2 



South, days 3 



Southwest, days 1 



West, days 



Northwest, days .19 



Weather 



Mean relative humidit}^, percent 70.6 



Mean cloudiness, percent 63 



Number of clear days 9 



Number of fair days 13 



Number of cloudy days 9 



Number hours bright sunshine 145 



Percent of possible hours of bright 



sunshine 51.2 



Thunder and lightning 



30.66 



29.27 



30.00 



1.38 



54.3 

 -1.9 



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; 1.0 1, 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 1940. 



