The Collaborative International Dictionary of English v.0.48:
Southwesterly \South`west"er*ly\, a. To ward or from the southwest; as, a southwesterly course; a southwesterly wind. [1913 Webster]WordNet (r) 3.0 (2006):
southwesterly adj 1: coming from the southwest; "the winds are southwesterly" [syn: southwesterly, southwest] 2: situated in or oriented toward the southwest [syn: southwest, southwestern, southwesterly]