How weather alert radios work

A weather alert radio is a receiver parked on one NOAA Weather Radio frequency around the clock, listening for a short digital message that names your county. When one arrives, it alarms; the rest of the time it sits silent. This page explains the machinery, then the reasons it beeps when nothing is happening.

What happens when a warning is issued

The chain from a meteorologist's decision to the alarm on your nightstand takes seconds:

1. Your NWS forecast office issues a warning. The office writing the warning is the same one assembling the broadcast on your transmitter.
2. The transmitter interrupts its loop. The routine forecast cycle stops for the alert sequence.
3. The SAME header goes out. Three bursts of harsh digital noise, the sound of a fax machine clearing its throat. Encoded inside: what the event is, which counties it covers as six-digit SAME codes, and how long the alert runs.
4. Your radio decodes the header and compares the county codes against the ones you programmed. No match: it stays silent, which is the feature you bought it for. Match: it alarms.
5. The 1050 Hz attention tone follows the header. Radios without SAME decoding, and there are decades of them still plugged in, trigger on this tone instead, for every alert the transmitter carries.
6. The voice message reads the warning. SAME radios that alerted un-mute so you hear it.

The county match in step 4 is the difference between a radio you trust and a radio you unplug. Out of the box most units alert for every county the transmitter reaches; programming your own codes is the five-minute job that fixes it, walked through in the SAME code guide.

The three alert modes

Most SAME radios offer a choice of what "alarm" means. On the Midland WR120, the desk unit the buyer's guide names, the menu calls them:

• Voice - the alert tone sounds for 8 seconds, then the broadcast audio plays for 3 minutes, so you hear the actual warning.
• Tone - the alert tone sounds for 3 minutes or until you press a button. You then decide whether to listen.
• Display - text scrolls on the screen, no sound. For places a siren would do more harm than good.

Other brands use different names for the same three ideas. Voice is the setting most people want at home: the point of being woken is finding out why.

Why is my weather radio beeping?

In rough order of likelihood:

It's Wednesday, late morning. Every NWR transmitter runs a required weekly test, most offices between 10 AM and noon local; it waits for fair weather if storms threaten. The display reads "Weekly Test." Not a malfunction - and it doubles as proof your programming works.

A monthly test. The broadcast also relays the Emergency Alert System's required monthly test.

"CHECK RECEPTION," with a beep every 10 minutes. WR120-family radios raise this alarm when nothing has been received for 10 days - and since the weekly test counts, a healthy radio never gets there. The radio has gone deaf: moved, antenna dropped, wrong channel, or marginal signal. Re-tune it (the finder lists every transmitter covering your county), reposition it, and the alarm clears on the next received alert. Pulling power and batteries for ten seconds clears it now; SAME codes survive, the clock needs resetting.

A low battery. The WR120 shows a battery icon rather than sounding; some other models chirp. Backup batteries run about 75 hours on standby, so a unit that rode out a long outage is due fresh ones.

It alarms for weather two counties away. The radio is in "any" mode or carries someone else's codes. The fix is the SAME programming walk-through.

Setting it up

Program your county's SAME code and the code of the neighboring county your weather usually arrives from. Set the alert mode to Voice and leave the radio plugged in with fresh backup batteries. When the Wednesday test fires, you have your proof the alarm works; until you have heard it trigger once, treat the radio as unprogrammed.

Where the data comes from

Every county's SAME code and transmitter frequency is in the NOAA Weather Radio Finder or the state-by-state tables, both built from the NWS's own coverage listing. If you are still choosing a radio, the buyer's guide covers the three features that matter; the Midland WR120B (Amazon) used as the example throughout this page is the plain desk unit named there.