500 Eighth Annual Report of the 



ing full account of the manner of oibservation in eacli case. la 

 the course of preparation of this paper a careful examination 

 was made of the records of humidity published by the State 

 Bureau; but, aside from the facts mentioned regarding the Cham- 

 plain and St. Lawrence valleys, no local peculiarities in the dis- 

 tribution of moisture were found of a sufficiently marked char- 

 adter to warrant publication until more extended observations 

 can be obtained. In general, there appears to be the usual slight 

 increase of humidity with altitude over the plateau regions, in 

 summer; but otherwise, the values given for the Signal Service 

 sitations may toe considered to hold true also throughout the 

 adjacent territory. 



GEj^ERAL CLIMATIC DATA AND NOTES. 



» 



Resume of Climatic Elements at New York City. 



(Values derived from U. 8. Weather Bureau records, unless otherwise specified.) 



Normal Tbmpkraturps: Annual, 51.6°; January, 30.6°; July, 73.4°. 



C100° in 1881, U. S. station. 



Maxima: Average of annual maxima, 94°; highest < 10i° in 1881, Centrnl Park. 



( 104° in 1825, Fort Columbus. 



-6.0° in 1875 and 1880, at U. S. station. 

 Minima: Average of annual minima, + 1°; lowest. •^ — 6.0° in 1880 and 188a. at Central Park. 



-12.0° in 1866, at Fort Columbus. 



est.<- 



Daily variations: Mean daily range: Greatest, 17.0°, in June; least, 13.2°; in December. 

 Daily periodic change, or amplitude, greatest. 11.5°, in June; least, 6.7°, in December. Average 

 variability of successive daily means, in January, 6.5°. 



Precipitation: Average annual, 45.31 inches; greatest average monthly, 4.77 inches, in 

 August; least average monthly, 3.05 inches, in May. 



Number of rainy days: Greatest, 39 per cent, in January and February; least, 31 per cent, in 

 September and October. 



Cloudiness: Annual percentage, 50.5, greatest, 57 per cent, in January; least, 46 per cent, in 

 September. 



No. clear days, year . . 101 .0 

 No. clear days, Jan .. 7.6 

 No. clear days, Sept.. 10.1 



No. p'tly cl'dy d'ys, year. . 155.0 

 No. p'tly cl'dy d'ys, Jan . . 12.1 

 No. p'tly cl'dy d'ys, Sept.. 11.7 



No. cloudy days, year . . 109.0 

 No. cloudy days, Jan. . . 11.3 

 No. cloudy days, Sept. . . 8.3 



Mean relative humidity: Annual, 70 per cent; greatest, 74 per cent, in January; least, 65 per 

 cent, in April. 



Averaqe date of first snovj, November 16th; average date of first killing frost, November 5th; 

 average date of last killing frost of spring, April 13th. 



Average velocity of the wind in miles, per hour: 



Jan. Feb. Mar. April. May. June. July. Aug. Sept. Oct. Nov. Dec. Year. 



11.0 11.4 11.6 8.9 7.9 7.7 7.4 7.3 8.0 9.5 10.1 10.9. 9.30 



