The San Francisco Zoo is opening its gates for a free admission day.

Let's be real: the SF Zoo, nestled out on the western edge of the city along the Great Highway, doesn't always get the love it deserves. It's not the flashiest zoo in America, and it sits in one of the foggiest corners of an already fog-prone city. But it's ours, and the fact that it periodically drops the admission fee — normally $28 for adults — is a welcome gesture.

Free admission days are a smart play. They get foot traffic through the door, introduce new families to the zoo, and build the kind of goodwill that translates into memberships, gift shop purchases, and future visits at full price.

If you're planning to go, a few words of advice: get there early. Free days draw crowds, and parking around the zoo can be a headache on a normal Tuesday, let alone when half the city shows up with strollers. Take the L-Taraval if you can — it drops you practically at the entrance.

For families looking for affordable things to do in a city where a casual lunch for four can run you $80, this is a no-brainer. The zoo has made solid improvements in recent years, and the playground alone is worth the trip for anyone with kids under eight.

Just check the weather first. It's the Outer Sunset. You've been warned.