 A tropical wave emerged off the western coast of Africa in mid @-@ August , acquiring sufficient organization to be declared a tropical depression by 06 : 00 UTC on August 18 while located about 765 mi ( 1 @,@ 230 km ) southwest of Cape Verde . The depression intensified into Tropical Storm Danny six hours later . Steered generally westward , the cyclone initially struggled to intensify quickly in the midst of abundant Saharan Air Layer ( SAL ) , but it managed to attain hurricane intensity around 12 : 00 UTC on August 20 . Thereafter , Danny began a period of rapid deepening , becoming a Category 3 hurricane and attaining peak winds of 125 mph ( 205 km / h ) early on August 21 . The negative effects of dry air and increased shear began to affect the cyclone after peak . 
