Climate of Central America. 157 
c. Costa Rica. 
The climate of Costa Rica depends on its situation in the tropics, on the 
position of the sun at different times of the year, and on the topography, but 
owing to the narrowness of the country and its situation between the two great 
oceans, it is well-tempered by the alisios (northeast trades) and other winds. 
The prevailing wind is from the northeast, or, better north-northeast and 
east. During August, September and October an increase of the northwest 
winds causes the heavy rains of that season. West-northwest and northwest 
winds blow also from May to August. The coldest month is January; 
December and February are relatively cold. The hottest months are May 
and June. ‘The course of the temperature has all the characters of an insular 
climate, without having so much humidity. The oscillation of the average 
temperature is greatest in March and during the dry season, as at that time 
the sky is clear and the soil exposed to uninterrupted insolation during the 
day, while the earth’s radiation of heat during the night is rapid. The daily 
oscillation is considerable also during the dry season, and continues during the 
first month of the rainy season, according 10 the conditions of the sky. 
The sky in San Jose is ordinarily clear between midnight and noon, even 
during the most rainy months, and cloudy the rest of the twenty-four hours. 
Although the rainfall is abundant here from May to October, with rare ex- 
ceptions they do not last more than a few hours each day. The mornings 
are generally splendid and the air very pure, and nearly every day the sunset 
can be clearly observed. From May to November, there are about two hours of 
copious rain daily between one and four o’clock in the afternoon, averaging, with 
great regularity, from ten to twelve inches a month, and from seventy to eighty 
inches during the year. Towards the end of June, there is a short dry period 
called »Veranillo de San Juan«. Through the Desengano and Palma passeSs, the 
northern rains penetrate a short distance every day, and the northern descent hu 
the Palma Pass toward Carillo is probably the t of the republic. 
The rainy season on the Caribbean slop 
tespond to that of t acific. In et, were? 
and on the oh ei of the "volcanos Turrialba, Irazu, Barba and 
Poas, it rains more or less during the entire year; 
it rains nearly continuously, and the mo 
the surroundings of the volcano of Orosi are seldom with ; 
there are cloudbursts of tremendous POWeh broadening rivers for mi 2 
The climate of Talamanca in vety un ximity to t u 
and in the lower course of the rivers @ simi limate prevals. 
normal years, there are two dry and two wet season®. 
last until the end of 
eavy showers, and extensive rains characterize the a 
November ber and January. The dri nths are February, Mat 
ih :  sivind rise to fogs and rains. 
and April. The high region is extremely humid, giving IS 
