The Collaborative International Dictionary of English v.0.48:
Raininess \Rain"i*ness\ (r[=a]n"[i^]*n[e^]s), n. The state of being rainy. [1913 Webster]WordNet (r) 3.0 (2006):
raininess n 1: (of weather) the badness of the weather; "they were wearied with the foulness of the weather" [syn: foulness, raininess]