The Collaborative International Dictionary of English v.0.48:

Sleety \Sleet"y\, a.
   Of or pertaining to sleet; characterized by sleet; as, a
   sleety storm; sleety weather.
   [1913 Webster]

WordNet (r) 3.0 (2006):

sleety
    adj 1: consisting of or of the nature of frozen or partially
           frozen rain

Moby Thesaurus II by Grady Ward, 1.0:

51 Moby Thesaurus words for "sleety":
   Siberian, algid, arctic, below zero, biting, bitter, bitterly cold,
   bleak, boreal, brisk, brumal, cold, cold as charity, cold as death,
   cold as ice, cold as marble, crisp, cutting, freezing,
   freezing cold, frigid, gelid, glacial, hibernal, hiemal,
   hyperborean, ice-cold, ice-encrusted, icelike, icy, inclement,
   keen, nipping, nippy, numbing, penetrating, piercing, pinching,
   raw, rigorous, severe, sharp, slushy, snappy, stone-cold, subzero,
   supercooled, winterbound, winterlike, wintery, wintry