166 
CLIMATE. 
Thus the rainy season commences on the Gulf coast about the 
first of July and ends about the first of November. On that 
portion of the Isthmus included between the Jaltepec and Sara- 
bia rivers, the rainy season commences about the first of June 
and ends in December ; and at El Barrio it commences about the 
first of July and ends in October. 
The rainy season, as above limited, includes only those months 
in which the rains prevail to a considerable extent ; but there is 
usually a month, both preceding and following the rainy season 
as above defined, which is more or less showery, but these 
showers generally occur in the night. In some parts of the 
more elevated mountain districts, the rains prevail to some ex- 
tent throughout nearly the whole year. This is particularly true 
of the northern slope of the Cordilleras, where the warm, humid 
air blowing from off the Gulf and across the Atlantic plains, 
first meets the cooler atmosphere of the mountains. 
The atmosphere of the northern portion of the Isthmus, ex- 
tending as far southerly as Boco del Monte, is damp ; but 
to the south of this point, its humidity becomes sensibly less, 
and at El Barrio and Chivela it is quite dry, and still more dry 
over the Pacific plains, where it scarcely ever rains. 
The sandy plains of the Pacific shore belong to one of the 
rainless districts of the American continent, which here em- 
braces the plateau of Guatimala and the table-land of Mexico. 
The proximity of the Gulf causes the rains on the northern side 
for the reasons before stated. The annual amount of the fall of 
rain on the Isthmus is considerable, especially in the central 
district from the Jaltepec to the Cordillera de la Hucamaya. 
At Guichicovi, and San Maria Chimalapa, it rains abundantly, 
and very often at San Miguel. At these times the table-land 
of Tarifa is covered with a thin mist, which disappears upon 
reaching the Portillo, or pass to the Pacific plains. 
These rains are not, however, of sufficient consequence to pre- 
vent out-door work for the whole of any one day. The annual 
fall of rain at Yera Cruz is 66 inches, just one-half the amount 
which falls in St. Domingo or Jamaica, and even less than that 
on the northern shores of the Gulf, as at New Orleans or in Flor- 
ida. It is also considerably less than falls at the Isthmus of 
