In the American South, it’s a beacon in dark places—a bright yellow sign in the middle of late-night interstate drives, a harbinger of warm comfort food served at any hour of the day.

Waffle House has been a staple across the region for more than than 60 years. The chain spans 25 states—many of which hug the gulf and Atlantic coasts—which means it has seen its fair share of tropical storms and hurricanes. And because all Waffle Houses are designed to run solely on gas power and just a few short-order cooks, it’s a particularly resilient chain when rough weather conditions strike—including Hurricane Harvey.

It’s for this reason that the Federal Emergency Management Agency (FEMA) considers these diners an unofficial index by which it can measure how catastrophic a storm is to a region, according to Yahoo Finance. If Waffle Houses are forced to close, chances are it’s a pretty bad weather event. FiveThirtyEight summed it up succinctly in 2016: “If Waffle House is closed, it’s time to panic.”

The chain deploys a “jump team” to restaurants in battered areas to fill in for employees who are dealing with storm damage on their own homes. The effectiveness is obvious. In 2011, when Hurricane Irene barreled up the East Coast, 22 Waffle House locations lost power yet only one of them stayed closed for more than a single day.

Of course, the chain is storied for other reasons, too. Its wide-ranging (but simple) menu includes all manner of breakfast staples, as well as steak. It’s a cultural icon frequented by blue-collar workers, lifelong truckers, and celebrities alike (Kim Kardashian and Kanye West once posed for a photo while on a late night stop). As Anthony Bourdain has put it: “It is indeed marvelous—an irony-free zone where everything is beautiful and nothing hurts; where everybody regardless of race, creed, color or degree of inebriation is welcomed.” And that’s a truth, even during some of the worst weather events imaginable.