4 ALLAN HANCOCK ATLANTIC EXPEDITION REPORT 



Surface water temperatures over the southern Caribbean region vary 

 from an average of 78° F. in February and March to an average of 83° 

 F. in September or October. In the northern Caribbean these figures are 

 approximately one degree less. Velero III readings in April ranged from 

 70° F. off Coche Island, Venezuela, to 78° F. off Galera Point, Trinidad, 

 with an average of 73.84° F. for nine observations, a figure fully four 

 degrees cooler than might have been expected according to the general 

 averages given above. 



Humidity data are available for only some of the islands. The monthly 

 mean for the dry season, February to April, is 60 per cent saturation. The 

 monthly mean for the wet season, October and November, is 84 per cent. 

 Early morning humidity may reach 92 per cent, as at Fort de France, 

 Martinique, but drops off during the sunlight hours to 81 per cent 

 (October and November readings). 



Rainfall is the most variable of the factors yet considered. Average 

 annual rainfall varies from 20^ inches for the arid section of Venezuela 

 including Lake Maracaibo and the Dutch West Indies to over 100 inches 

 along the north coast of Trinidad. The dry season is from December to 

 April, with May included in the Gulf of Venezuela. It thus coincides 

 with, or follows shortly after, the period of steady northeast winds. From 

 May on, the frequency of rains increases, culminating in the late summer 

 or early autumn months of August and September and decreasing through 

 October and November. 



In conclusion, it will be seen that the Caribbean region is one of high 

 average temperatures and humidity, the oppressive effects of which are 

 mitigated by the steady and dependable trade winds which exercise a 

 moderating influence except where prevented by local conditions. The 

 entire region is free from fog, but cloudiness is common as a prelude to 

 the rains of the late summer period. 



The general path of the tropical hurricanes which scourge the north- 

 ern and eastern Caribbean islands is from southeast to northwest, with a 

 tendency toward deflection to the north or east in the higher latitudes. 

 Either the Barbados-Haiti-Cuba axis may be followed to New Orleans 

 or the Barbuda-Puerto-Bahamas axis to Miami, with devastating results 

 to palm groves and sugar plantations. Of the seven historic storms the 

 courses of which are plotted in Sailing Directions for the West Indies, 

 only that of June 27- July 6, 1933, entered the Caribbean at a latitude 

 low enough to affect Trinidad and eastern Venezuela, and only that of 

 November, 1932, dipped near enough to the South American coast to be 

 felt at Cape la Vela, Colombia. For complete discussion of these cyclonic 

 storms the reader is referred to the above-mentioned Sailing Directions. 



