Beach warning flags
A flag is a judgment made by people watching that water this morning. It outranks every forecast on this site, including ours.
· Follows National Weather Service guidance
If someone is in trouble in the water, call 911 and alert a lifeguard. Do not swim out after them. People drown attempting rescues far more often than the person they went in for.
The flag system varies between states, counties and individual beaches. The colours below are the widely used convention, and the rules attached to each one are set locally. The sign at the beach entrance states what the colours mean there — read it before you rely on this table.
The colours
- Green — Low hazard Calm conditions. Caution still applies — green describes the surf, and it says nothing about your own swimming ability or about a current that forms after the flag went up.
- Yellow — Medium hazard Moderate surf or currents. Weak swimmers are advised to stay out, and everyone else should stay close to a lifeguard.
- Red — High hazard High surf or strong currents. Many beaches restrict swimming to knee depth or close the water entirely under a single red flag.
- Double red — Water closed to the public Entering the water is prohibited, and in several states it carries a fine. This flag is not advice.
- Purple — Dangerous marine life Jellyfish, stingrays or other hazardous species are present. It is flown alongside a colour flag, and it does not refer to sharks on most beaches.
- Red over yellow — Supervised area A pair of these flags marks the stretch of water lifeguards are actively watching. Swimming between them is the single most effective safety decision on the beach.
- Black and white quartered — Surfcraft area Reserved for boards and surfcraft, and closed to swimmers, to keep hard equipment away from people in the water.
Why the flag beats the forecast
A National Weather Service rip current risk level covers a stretch of coastline and is issued once or twice a day. It is a genuinely useful input, and where it exists for a spot we publish it with the office and issue time attached.
A flag is narrower and fresher: it applies to the beach you are standing on, and someone changed it when the water changed. When the two disagree, the flag is the one to follow — and a lifeguard standing next to it can tell you where the currents are running today, which is a level of detail no forecast reaches.
Swim between the flags
A pair of red-over-yellow flags marks the water lifeguards are actively watching. Choosing that stretch over a quieter one further along the beach is the most effective decision available to a swimmer: the United States Lifesaving Association puts the chance of drowning at a guarded beach at roughly one in eighteen million.
An empty beach with no flags at all is the case worth thinking about in advance. It means nobody is watching and nobody has assessed the water — so the assessment falls to you. Reading the surf for rip currents is worth practising before you are in that position.
What a flag does not cover
Flags describe the state of the water. They carry no information about how well you swim, how cold the water is, or how tired you will be in twenty minutes. Cold water in particular is a separate hazard with its own timeline — the wetsuit chart starts from the measured water temperature at each spot, with the station named.
And a flag is a snapshot. Surf builds, tides turn, and a current can form after the flag went up. If the water in front of you looks different from what the colour says, trust the water — the reasoning is on the safety disclaimer.
Common questions
What does a red flag mean at the beach?
High hazard: high surf, strong currents, or both. What it permits depends on the beach — some restrict entry to knee depth, others close the water. Two red flags flown together always mean the water is closed to the public.
What does a purple flag mean?
Dangerous marine life is present — commonly jellyfish, man o' war or stingrays. It is flown in addition to a hazard colour, not instead of one, and on most beaches it does not indicate sharks.
Is it safe to swim under a green flag?
Green means low hazard, which describes the surf rather than guaranteeing your safety. Rip currents can run under a green flag, particularly beside a pier or jetty, and conditions change after the flag goes up. Swimming near a lifeguard still applies.
Are beach flags the same everywhere in the United States?
No, and this matters. Green, yellow, red and double red are broadly consistent, but the specific rules attached to each colour are set locally and vary between states, counties and individual beaches. Read the sign at the beach entrance — it states what each colour means there.
What do two red flags mean?
The water is closed to the public. Entering it is prohibited, and in some jurisdictions — parts of the Florida Panhandle among them — it carries a fine or arrest.
This page explains a hazard. It is not a clearance to enter the water, and it does not replace a lifeguard, a posted flag or a National Weather Service warning — see the safety disclaimer. Where the wording here follows the National Weather Service, the authoritative version is always theirs, and it may be newer than ours.