Unseasonably warm, cold, or mild weather is warmer, colder, or milder than it usually is at the time of year. a spell of unseasonably warm weather It was unseasonably mild for late January. unseasonably warm/cold/hot etc used for saying that the weather is warmer, colder etc than usual at a particular time of year
Not seasonable; being, done, or occurring out of the proper season; ill-timed; untimely; too early or too late; as, he called at an unseasonable hour; unseasonable advice; unseasonable frosts; unseasonable food