What is Off season ?
Off season is (noun) a time of year when there are fewer travellers, and when air fares and hotel prices are cheaper In February, British Airways was offering special off-season round the world fares. Tour operators try to get more people to travel during the off season. Also called low season. Antonym high season (adj), (adv) in the off season special off-season round-the-world fares We travelled off-season, to take advantage of the low fares.
source: Easier English, Student Dictionary Upper Intermediate Level