MESA AND FOOTHILL VEGETATION 



21 



Temperature Compared with That of Other Parts of the United 

 States. — The climate of Boulder may be called mild; since American 

 climates with which it is likely to be compared are more severe. The 

 mean for the year is about the same as that of New York City, but the 

 winters in Boulder are warmer and the summers cooler. Briefly described 

 it may be said that Boulder is as warm in winter as St. Louis and as 

 cool in summer as St. Paul. The relation of the climate of Boulder to 



Fig. 2. — Rainfall by Months. — Boulder (heavy black line) compared with New- 

 York, St. Louis, St. Paul and Phoenix, Ariz. It is seen from the shape of the curve that 

 the general distribution of rainfall is about the same in Boulder as in St. Louis and St. 

 Paul. The month of greatest rainfall at Boulder is April instead of June, as in the Mis- 

 sissippi valley cities. Comparison with rainfall of Phoenix, Ariz., shows that Boulder is 

 in no sense to be considered as a desert station. 



that of New York, St. Paul, St. Louis and Phoenix, Ariz., is shown in 

 Fig. 1. The warm winters at Boulder may be expected to permit the 

 growth of southern plants which are able to survive here when they 

 would be unable to live if winters were more rigorous. On the other 

 hand, the coolness of summer is favorable to the growth of northern 



