Longman Dictionary of Contemporary English
low season
noun
EXAMPLES FROM CORPUS
▪ A week's accommodation costs between £15 in low season and £48 a person.
▪ Lots of different sports are available, although some sports may be limited during low season and are subject to weather conditions.
▪ Many hotels offer discounts for stays of 3 nights or more, especially in the low season.
▪ The lowest fare is £309 midweek, low season.
▪ The lowest through fare from London straight to Redding is £385 midweek, low season.
Wiktionary
low season
n. In the tourist industry, the period of lowest demand. In a sun and sand resort this means the coldest and wettest months, whereas in a ski resort, this means the warmest months.
Usage examples of "low season".
It was a low season for tourists, and there were still plenty of people about, strolling, browsing inside the restored shops, and riding past in horse-drawn carriages driven by liverymen in knee breeches and three-cornered hats.