Seasonal /(?)/

Sea·son·al

Seasonal

a.
  1. Of or pertaining to the seasons.
  2. Occurring or being used in a specific season; as, seasonal items for sale.

Phrases & Compounds
Seasonal dimorphism
the condition of having two distinct varieties which appear at different seasons, as certain species of butterflies in which the spring brood differs from the summer or autumnal brood.