or 



22 TRANSACTIONS OF THE 



COAST CLIMATE OF CALIFORNIA. 



Bv Johx W. Robertson, M.D., Crescent City, Del Norte County, as published in the State 



Board of Health Report for 1886. 



The coast climate of California possesses many peculiarities which dis- 

 tinguish it from that found elsewhere in the United States, and which pre- 

 eminently recommend it to the health-seeking invalid. 



These peculiarities consist in uniformity of temperature, the distribution 

 of rain, and the fact that there are only two seasons. 



TEMPERATURE. 



The temperature varies little, Summer or Winter. There is not the 

 enervating Summer heat which characterizes the interior valleys, nor in 

 Winter is the rain so constant or disagreeable as to forbid outdoor life. 



In no Winter month is the average temperature below 45°, nor in Summer 

 does it rise above 60°. 



As Chairman of the Committee on Medical Topography, I made a report 

 to the State Medical Society, in which this uniformity of temperature was 

 discussed, as follows: 



While the climate of California is mainly due to its situation, midway the temperate 

 zone, the remarkable uniformity of temperature is due to local causes. The great law 

 that, in the northern hemisphere, all western coasts are warmer than the eastern, is pecu- 

 liarly well pronounced when the eastern is compared with the western coast of the United 

 States. 



The mean isotherm of 50°, which passes through New York, latitude 41°, bears north- 

 ward as it crosses the continent, touching the Pacific at Vancouver Island, latitude 49°. 



Nature also draws isotherms in her distribution of trees and plants. While on the 

 eastern coast 60° is the northern limit of coniferre, they are found as high as 68° and 70° in 

 regions adjoining the Pacific. It is thus evident that the climate of Northern California 

 is much more temperate than that of the Eastern States which are situated in the same 

 latitude. This does not hold true of Southern California. Here the conditions are reversed. 

 San Diego, in the same latitude as Charleston, is 8° cooler. San Francisco and Washing- 

 ton — in the same latitude, and having the same mean annual temperature — have climates 

 very dissimilar, owing to the great difference between the mean Summer and Winter tem- 

 peratures of Washington, which amounts to 40°, and the small difference in San Fran- 

 cisco, being not over 8°. The mean annual temperature of Santa Barbara is 60°; that of 

 San Francisco is 55°; nor does it fall below this on the northern coast. In Crescent City, 

 latitude 42°, the temperature is as uniform as in San Francisco, frost and snow being of 

 even rarer occurrence. 



Isothermal lines, which normally run east and west, are, as they near the Pacific, 

 deflected north and south, and define three distinct climatic belts. These may be named : 

 coast, valley, and mountain; and while they resemble each other in having only two sea- 

 sons, they are dissimilar in other respects ; each presenting peculiar attractions for different 

 classes of invalids. These differences depend upon the topography of the country, and are 

 of degree rather than of kind; altitude, distance from the ocean, and situation with refer- 

 ence to mountain chains, giving to each region its characteristic climate. That of the 

 coast extends only a few miles inland, but stretches six hundred miles north and south. 

 It is characterized by a mild temperature, which varies little Summer or Winter — a fresh 

 sea breeze during the warm part of the day, fog in Summer, and an abundant downpour 

 of rain in Winter. Here perpetual Spring is found; the trees being principally fir, spruce, 

 and redwood, and the grass always green, the vegetation presents, both Summer and Win- 

 ter, a pleasing contrast to that prevailing in the valleys and mountains of the interior. 

 It is proper to include in this a large part of the inhabitable region of Southern California. 

 There the hills of the Coast Range, being low, offer little resistance to the cool ocean breeze, 

 and the effect is felt for many miles inland. The heat incident to the valleys greatly mod- 

 erates them, removes all rawness, and the result is a balminess exceedingly grateful to the 

 invalid. 



