FIPS (Federal Information Processing Series) codes are 6-digit numbers used by the National Weather Service (NWS) and NOAA Weather Radio (NWR) to pinpoint specific counties or parishes for weather alerts via the Specific Area Message Encoding (SAME) system. These codes allow users to program weather radios to only trigger alarms for their specific location, avoiding unnecessary alerts for distant areas. 

Key Uses and Structure of FIPS Codes in Weather:

• Targeted Alerting: FIPS codes allow the NWS to transmit warnings, watches, and advisories to precise geographic locations.

• SAME Technology: When a warning is issued, the NWS sends a digital "SAME" code, including the FIPS code, which your radio reads. If the FIPS code matches the one you programmed, the radio sounds the alert.

• 6-Digit Format: While FIPS county codes are 5 digits, for weather radio (NWR) purposes, they are used as 6 digits, where the first digit (0-9) often acts as a subdivision placeholder for a county, and the remaining 5 represent the state and county.

• County Targeting: For example, in California, a 6-digit code for a county is typically formatted as 0 + 2-digit state code + 3-digit county code (e.g., 006067 for Sacramento County).