Gulf of California — Roden 
29 
the dry steppe type, and in southern Sinaloa 
it is tropical. 
The distribution of air temperatures (Fig. 
5) shows a temperature minimum in January 
and February and a maximum in August and 
September. The annual range in temperatures 
increases from south to north and is some- 
what greater along the coast of Baja California 
than along Sonora and Sinaloa. The mean 
annual range at the entrance is around 10°C. 
and in the northernmost part about 20°C. The 
extreme annual range (Table 1) is approxi- 
mately twice the average annual range (Serv. 
Met. Mex., Boletin Anual). In general the air 
is warmer than the sea during the first half of 
the year and cooler during the second, except 
for Mazatlan, where the air is always cooler 
than the sea (Fig. 5). 
The distribution of winds (Table 2) shows 
that the monthly average wind velocities are 
quite low, lying between 1.5 m/sec and 6.1 
m/sec. The higher values are found in winter 
and spring. The direction of winds varies with 
season and with distance from the entrance. 
During winter, northerly winds are predom- 
inant in the entire Gulf, but in summer the 
southern half of the Gulf is mostly influenced 
by southerly winds. In the northern half, 
southerly winds blow only one or two months 
of a year. 
Winter gales of short duration, locally 
known as chubascos, are frequent and veloci- 
ties may occasionally reach 30 m/sec. 
Hurricanes are not as rare in the Gulf as is 
generally believed. Between 1910 and 1930 
thirty-nine were registered (Schott, 1935: 
280). These hurricanes, known as "El Cor- 
donazo,” may enter the Gulf any time be- 
tween May and November, but are most 
frequent in September and October (Fig. 6). 
Fig. 6. Paths of hurricanes in 1936. (After Serv. Met. Mex., Boletin Anual, 1936.) 
