MONTHLY SUMMARY 



September 1940 



Normal 



Extremes 



Barometer, in inches 



(Readings reduced to sea level) 



Maximum 30.43, 30th 



Minimum 29.48, lOlh 



Mean .semi-daily 30.032 



Range 0.95 



Air Temperature, in degrees F. 



Highest 85, 21.-t 



Lowest 30, 27th 



Mean 60.1 



Range 55 



Highest mean daily 77, 1st 



Lowest mean daily 45, 26th 



Mean maximum 72.6 



Mean minimum 47.6 



Greatest daily range 40, 29th 



Least daily range 5, 9th 



Precipitation, in inches 



Precipitation 1 J3 



Maximum precipitation in 24 hrs. 0.79, 25th 



Number of days with .01 or more 5 



Wind, in miles 



Total movement 3091 



Greatest daily movement 228, 'J 2nd 



Least daily movement 33, 19th 



Mean hourly velocity 4.3 



Maximum velocity 32, 5th, 26th 



Wind, direction 



Prevailing direction NVV 



North, days 10 



Northeast, days •. 



East, days 1 



Southeast, days 2 



South, days 3 



Southwest, days 4 



West, days 3 



Northwest, days 7 



Weather 



Mean relative humidity, percent 79 



Mean cloudiness, percent 47 



Number of clear days 16 



Number of fair days 7 



Number of cloudy days 7 



Number hours bright sun.shine 239 



Percent of possible hours of bright 



sunshine 64.1 



Thunder and lightning 21st 



First frost .Sept. 27 



30.45 

 29.57 

 30.06 



87.7 

 33.2 

 61.7 

 54.5 



4.26 



10 



3271 



4.5 

 25.9 



WSW 



73.6 



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, 191G; 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 1939. 



