388 



REPORT OF OFFICE OF EXPERIMENT STATIONS. 



CLIMATE. 



The climate of Porto Rico is characterized by a very uniform tem- 

 perature, abundance of rain, plent}^ of sunshine, high relative humidity, 

 and moderate to slow wind movement. The mean annual temperature 

 for the island is about 78° F. The warmest weather occurs in July, 

 August, September, and October, and the coldest in January and 

 February. The difference in temperature, however, between the 

 hottest and coldest month is only about 8° F. The changes from day 

 to day and from month to month are so slight that they are scarcely 

 perceptible. The greatest annual difference in temperature in different 

 parts of the island, as determined by seventeen United States Weather 

 Bureau stations in 1900, was only 4.8° F. The mean temperature is 

 slight^ lower in the elevated parts of the island than along the sea 

 shore. The weather is perpetual summer, with three hundred and 

 sixty -five growing days in each year. 



The annual rainfall varies greatly, attaining a maximum of 140 to 150 

 inches in the northeast part of the island, near El Yunque, and a 

 minimum of about 40 inches in places near the southern coast. 



The following table shows the monthly precipitation for each of four 

 localities on the island since the establishment of observations there by 

 the United States Weather Bureau. Prior to that period the only 

 continuous record is one that was kept at San Juan by the Spanish 

 Government. The mean of tjiis station for twenty-six years is as 

 follows: Temperature, 78.5°; rainfall, 54.51 inches. 



Rainfall (inches) in Porto Rico as recorded by the United States Weather Bureau, January, 



1899, to December, 1901. 



