MONTHLY SUMMARY 



September 1939 



Barometer, in inches 



(Readings reduced to sea level) 



Maximum 30.56, 19th 



Minimum 29.62, 10th 



Mean semi-daily 30.038 



Range 94 



Air Temperature, in degrees F. 



Highest 91, 16th 



Lowest 35, 19th 



Mean 61.4 



Range 56 



Highest mean daily 76.5, 16th 



Lowest mean daily 43.5, 27th 



Mean maximum 73.5 



Mean minimum 49.3 



Greatest daily range 36, 19th, 22nd 



Least daily range 5, 27th 



Precipitation, in inches 



Precipitation 2.97 



Snow 



Max precipitation in 24 hrs 1 .08, 27th 



Number of days with .01 or more 8 



Wind, in miles 



Total movement 3727 



Greatest daily movement 228, 17th 



Least daily movement 55. 8th 



Mean hourly velocity 5 2 



Maximum velocity 32, 10th 



Wind, direction 



Prevailing direction SSW 



North, days 6 



Northeast, days 1 



East, days 



Southeast, days 6 



South, days 8 



Southwest, days 3 



West, days 1 



Northwest, days 5 



Weather 



Mean relative humidity, percent 73.9 



Mean cloudiness, percent 47 



Number of clear days 13 



Number of fair days 11 



Number of cloudy days 6 



Number hours bright sunshine 218 



Percent of possible hours of bright 



sunshine 58.4 



Thunder and lightning 10th, 27th 



Frosts None 



First Frost 



Normal 



Extremes 



30.45 

 29.57 

 30.06 



87.7 

 33 2 

 61.7 

 54.5 



4.26 



10 



3271 



4.5 



25.9 



WSW 



736 



49.9 



10 



10 



10 



201 



54.9 



Sept. 21 



30 65, 1924 

 28 41, 1938 



1.99, 1938; .57, 1910 



97, 1895, 1929 

 24.5, 1914 



14 55, 1938; .52, 1914 



16, 1933; 3, 1903 

 4 686, 1896; 1,414, 1894 



80, 1938 



70, 1934; 27, 1908, 1914 



19, 1932; 2, 1907, 1928 



19, 1908; 3, 1889 



20, 1934; 4, 1908, 1916 



255, 1916; 106, 1934 



Aug. 22, '94, '95; Oct. 13, '09 



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. 



