on-season

[ on-see-zuh n, awn- ]
/ ˈɒnˈsi zən, ˈɔn- /

adjective

being a time of year that is the busiest or most popular for a specific activity; in season: on-season airfares.

adverb

in or during the busiest season: to travel on-season.

noun

a time of year that is the busiest or most popular for a specific activity: We stayed at the resort in the on-season.

Origin of on-season

by analogy with off-season