Not ready to say goodbye to summer yet? Then plan a getaway to San Diego, where often the highest temps of the year—and the lightest crowds—kick in during September and last well into October. After Labor Day, prices start to dip nicely, too.

From September through December, the Hyatt Regency Mission Bay Spa and Marina is offering an “Endless Summer” welcome credit that piles on more resort credits the longer you stay: Stay two nights and you get $75; visit three nights, and you earn $125; four nights, and you snag $150.  You can use the credits at the on-site restaurants—an easy way to absorb food costs—or at the all-organic Blue Marble Spa.

There’s certainly enough for the kids and spouse to do while you sneak away to the spa. The 430-room hotel has three pools with waterslides and water sports on the adjacent bay. It’s a short walk (or free shuttle ride) to Mission Beach, which has a sand beach, a boardwalk and an old-style amusement park called Belmont Park, which stays open pretty much year round. Plus, the resort is right next door to SeaWorld—whose crowds, come September, will have much slimmed down.

Note that the Endless Summer offer comes with one big hitch: a non-refundable, advance-purchase requirement. When we checked three-night stays in September, we found regular weekend rates starting at $244 a night in a room with two queen beds and a deluxe view. Meanwhile, the Endless Summer rate is $254—$10 more than the regular rate, but $42 higher than the advance-purchase rate of $212 a night. 

Deal or no deal? Come for the sun—but not necessarily this deal. When you do the math, you discover that what you get in resort credits is pretty much a wash with the $40 difference between the Endless Summer rate vs. advance-purchase rate. So if you’re willing to pre-pay anyway, you may as well just book the advance-purchase rate and not be tied to eating on-site.

The Endless Summer offer is based on availability and is good for stays through December 30. You must book by December 28. When booking online, use the promo code WELCRE, or mention the deal when calling 619/224-1234.