Reading the beach flags: what the colors are really telling you

Green, yellow, red, double red, purple. The flag system on Port Aransas beaches is the same standardized system used up and down the U.S. coast — and learning to read it takes about thirty seconds.

The colored flags flying from the lifeguard towers and beach-access points are not decoration. They're the United States Lifesaving Association's standardized beach warning system, the same one used on Galveston, the Florida panhandle, the Outer Banks, and most major U.S. ocean beaches. Once you learn the four colors, you can walk onto any flagged beach in the country and know what the conditions are before you put a toe in the water.

Here's the system, the way our local lifeguards fly it.

Green flag: low hazard. Calm conditions, light or no current, small surf. A good day to swim, a good day to put kids in the water, a good day to relax about it. Green doesn't mean zero risk — every ocean swim carries some — but the conditions are about as friendly as they get.

Yellow flag: medium hazard. Moderate surf, moderate current. This is the most common flag we fly. Adults who can swim should be cautious; less-confident swimmers should stay in chest-deep water or shallower; non-swimmers should stay at the water's edge. Yellow is the flag where a lot of trouble starts, because people see that it's not red and assume that means it's fine. It means be alert.

Red flag: high hazard. Strong surf, strong currents, dangerous conditions. The lifeguards are flying red because they expect to be busy. Stay in shallow water — knee deep or less — and keep kids closer than that. If you're not a confident ocean swimmer, just don't get in past your ankles on a red-flag day. The Gulf doesn't look that dramatic from shore on a red day. The danger is what's under the surface.

Double red flag: water closed to the public. Lifeguards have determined conditions are too dangerous and the beach is closed for swimming. Going in anyway is a fineable offense, and more importantly it puts the people who would have to come get you in serious risk. Double red is rare. When you see it, believe it.

Purple flag: dangerous marine life. Usually jellyfish, occasionally Portuguese man o' war that have blown in on the wind, sometimes a shark sighting that closed a stretch of beach earlier in the day. Purple often flies alongside one of the other hazard colors. Wading is generally fine; swimming and bodysurfing put more skin in contact with the water. Wear something on your feet if you can.

A few practical things the flags don't tell you that we wish they did.

Rip currents can run on green-flag days. Rips don't always require big surf to form; a small current cutting through a sandbar gap can pull a person off their feet in waist-deep water. The signs are the same regardless of flag color: a darker channel of water cutting through breakers, a patch where the waves don't break the way they do on either side, foam or sand or seaweed moving straight out from shore. If you spot one, don't swim across it; swim parallel to shore until you're out of the current, then come in.

Hand signals from the lifeguards mean something. An arm raised straight up means hold position; a horizontal wave means come in; pointed signals usually mean move along the beach in that direction. If a guard is whistling at you, they mean you. Look up and read what they're indicating.

Flag conditions change. The lifeguards swap flags through the day as wind, swell, and tide shift. A green morning can be a yellow afternoon. Glance up when you come back from a lunch break. The current flag is the current truth.

And finally: when in doubt, ask. The guards on the towers want you to come ask. They'd rather answer a question than pull someone out. That's the whole job.