unseasonable

adjective

1. not seasonable; being out of season; unseasonal: unseasonable weather.
2. not befitting the occasion; untimely; ill-timed; inopportune; inappropriate: Their visits were usually unseasonable.

adjective

1. (esp of the weather) inappropriate for the season
2. untimely; inopportune

adj.mid-15c., “inopportune,” from un- (1) “not” + seasonable. In reference to weather, “not appropriate to the time of year,” it is recorded from 1510s.