Monthly Summary 



September. 1931 



Normal 



Extremes 



Barometer 



(Readings reduced to sea level) 



Maximum 30.48, 30th 



Minimum 29.57,24th 



Mean semi-daily 29.989 



Range 91 



Air Teinpera<ure 



Highest 94,11th 



Lowest 36, 30th 



Mean 64.8 



Monthly range 58 



Highest mean daily 80.0, 11th 



Lowest mean daily 49.5, 28th 



Mean maximum 75.6 



Mean minimum 53.9 



Greatest daily range 35,9th, 30th 



Least daily range 8, 26th 



Precipitation 



Precipitation. In inches 2.50 



Snow, in inches 



Maximum precipitation in 24 hrs. 1.06, 



15th 

 Number of days on which .01 or 



more inches of I'ain fell 10 



Wind (miles) 



Total movement 3,481 



Greatest daily movement .... 273, 24th 



Least daily movement 41, 9th 



Mean hourly velocity 4.7 



Maximum velocity for 5 min 32, 24th 



(corrected to conform to H curi anemometer) 



Wind (direction) 



Prevailing direction nw 



North, days 8 



Northeast, days 1 



East, days 1 



Southeast, days 6 



South, days 5 



Southwest, days 1 



West, days 3 



Northwest, days 5 



Wt-ather 



Mean relative humidity, per cent . . 70.6 



Mean cloudiness, per cent 49 



Number of clear days 17 



Number of fair days 7 



Number of cloudy days 6 



Number of hours bright sunshine 248.2 

 Percent of possible hours of bright 



sunshine 66 



Thunder and lightning . . 15th, 22nd 

 First Frost 



30.45 



29.59 



30.068 



.86 



87.4 

 32.8 

 61.6 

 54.6 



3.79 



3,252 



4.5 

 22 



80.0 

 48.7 

 9 

 11 

 10 

 202.5 



54 



19 



30.65, 1924 

 29.32, 1900 



1.20, 1924; 0.57, 1910 



97.0, 1895, 1929 

 24.5, 1914 



8.74, 1907; 0.52, 1914 



15, 1918; 3, 1903 



4,686, 1896; 1,414, 1894 



39, 1915 



89, 1927; 70.7, 1892 

 65, 1889; 27, 1908, 1914 



18, 1891; 2, 1907, 1928 



19, 1908; 3, 1889 



19, '89, '07; 4, '08, '16 

 255, 1916; 110, 1907 



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



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

 month. The second column g:ives averages based on observations made from 1»89 to 

 lUL'a. Tlio third column gives extremes observed from 1H8'.) to liKiO. 



