Seasonal (adjective)

1. Relating to a particular season of the year.
2. Occurring at or dependent on a particular season.
3. Recurring or appearing at specific times in the year.
4. Related to or varying with the seasons.

Origin:

Mid 16th century: from season + -al.

Examples:

1. The store has a wide selection of seasonal fruits and vegetables.
2. Seasonal allergies are common in the spring.
3. The park has a seasonal waterfall that only runs in the summer.
4. The restaurant has a seasonal menu that changes with the availability of ingredients.
5. The company hires a large number of seasonal employees for the holiday season.