A weather radio is a specialized radio receiver that is designed to receive a public broadcast service, typically from government-owned radio stations, dedicated to broadcasting weather forecasts and reports on a continual basis, with the routine weather reports being interrupted by emergency weather reports whenever needed. Weather radios are typically equipped with a standby alerting function—if the radio is muted or tuned to another band and a severe weather bulletin is transmitted, it can automatically sound an alarm and/or switch to a pre-tuned weather channel for emergency weather information. Weather radio services may also occasionally broadcast non-weather-related emergency information, such as in the event of a natural disaster, a child abduction alert, or a terrorist attack.

They generally broadcast in a pre-allocated very high frequency (VHF) range using FM. Usually a radio scanner or a dedicated weather radio receiver is needed for listening, although in some locations a weather radio broadcast may be re-transmitted on an AM or FM broadcast station, on terrestrial television stations, or local public, educational, and government access (PEG) cable TV channels or during weather or other emergencies.

Weather radios are generally sold in two varieties: home (stationary) or portable use. Portable models commonly offer specialized features that make them more useful in case of an emergency. Some models use crank power, in addition to mains electricity and batteries, in case of a power outage.

Smaller hand-held weather receivers generally do not support the Specific Area Message Encoding (SAME) alert type encoding (though there are some that do) but allow hikers and other explorers to listen to weather reports without packing a heavy and bulky base station radio. Some models have a built-in flashlight and can double as a cellphone charger. Some also serve as a more general emergency radio and may include multiband and two-way communication capability. "Scanner" radios designed to continuously monitor the VHF-FM public service band are already able to receive weather channels.

Besides SAME alerting capability, modern weather radio receivers, especially those that are compliant with CTA standard 2009-B, may include visual alerting elements (e.g., multicolored LED indicator lights) and allow for the use of external devices (e.g., pillow vibrators, bed shakers, strobe lights, and loud sirens, which attach via an accessory port) to alert those who are deaf or hearing impaired.

Both private and commercial seagoing vessels need accurate weather reports, in order to avoid storms that might damage or capsize the vessel, or make paying passengers uncomfortable. One such service is Navtex, which is a low-frequency facsimile radio service.

The National Oceanic and Atmospheric Administration, Environment Canada, the Mexican Seismic Alert System and the Bermuda Weather Service operate their government weather radio stations on the same marine VHF radio band, using FM transmitters, and the same seven frequencies (162.400-162.550 MHz) as NOAA Weather Radio (NWR). Bermuda only uses 162.550 (land) and 162.400 (marine). NWR transmitters operate VHF-FM between 5–1,000 watts. NWR channels operating in the range of 162.3625-162.5875 MHz (WX1-WX7) have a band spacing of 25 kHz and may have bandwidths up to 16 kHz. The original "weather" frequency was 162.550 MHz, with 163.275 MHz initially recommended as a backup and later dropped due to interference problems with other federal agencies.

NOAA Weather Radio, Weatheradio Canada and SARMEX all refer to the seven stations by their frequencies:
162.400, 162.425, 162.450, 162.475, 162.500, 162.525 and 162.550 MHz.