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UNIVERSITY OF COLORADO STUDIES 



are warm and dry; winters are mild with little precipitation. Snow- 

 fall is not sufficient for sleighing except in unusual seasons. Most of 

 the snow comes in early spring, frequently melting as it falls. The 

 region is semi-arid; mesophytic plants grow only in gulches or seepage 

 areas unless irrigated. Precipitation is, however, greater than on the 



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



Fig. i. — Annual March of Temperature. — Boulder (heavy black line) compared 

 with St. Paul, New York, St. Louis and Phoenix, Ariz. The mean temperature for 

 December and for January is seen to be higher at Boulder than in New York or St. Louis 

 while the summer temperature is lower at Boulder than in these cities or even St. Paul. 



plains, Boulder having about four inches more rainfall than Denver 

 which is on the plains about twenty-five miles away. The general 

 character of the climate is shown in Table I, kindly prepared by Hon. 

 S. A. Giffin, voluntary observer at Boulder. 



