unseasonable (adj.)youdaoicibaDictYouDict[unseasonable 词源字典]
mid-15c., "inopportune," from un- (1) "not" + seasonable (adj.). In reference to weather, "not appropriate to the time of year," it is recorded from 1510s. Related: Unseasonably.[unseasonable etymology, unseasonable origin, 英语词源]