not in keeping with (and usually undesirable for) the season
A sudden unseasonable blizzard. Unseasonable bright blue weather in November.
source: WordNet 3.0
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.
source: Webster 1913
adjective satellite
badly timed
An ill-timed intervention. You think my intrusion unseasonable. An untimely remark. It was the wrong moment for a joke.
