Here’s the deal on scoring affordable ski vacations: If you hit the slopes at the right time, you may be able to find some significant deals.

If you see a deal being promoted, find out if there are blackout dates. That will tip you off to the resort’s high season. This year, those dates will generally fall between December 18 and January 2, and February 12-15, also known as Presidents Day weekend.

Some so-called “early-bird specials” are actually meant to get you to lock in your dates early.

The Little Nell in Aspen, Colorado, is offering two free lift tickets for every night booked through the entire ski season—but it’s only based on availability. So unless you jump on it early, and are flexible with dates, you could miss out.

Other deals are only valid during traditionally slow periods. At Deer Valley in Utah, guests can book two nights in a condominium, and get a third night free through December 4.

At Vail and Beaver Creek resorts, they’re throwing in lift tickets and a free night’s stay—but only for travel from Thanksgiving through the week before Christmas, and January 3 through early February … otherwise known as the dead weeks in travel.

In a similar deal, Sun Valley Resort in Idaho has a package starting the day after Thanksgiving through December 20, including one-night’s lodging and free skiing from just $67 a person.

The lesson is, start planning your ski travel now, and you may find some great deals out there.