An excessive heat warning is issued within 12 hours of the onset of the following criteria: heat index of at least 105°F for more than 3 hours per day for 2 consecutive days, or heat index more than 115°F for any period of time.
A heat advisory is issued within 12 hours of the onset of the following conditions: heat index of at least 105°F but less than 115°F for less than 3 hours per day, or nighttime lows above 80°F for 2 consecutive days.
A Fire Weather Watch is issued to alert fire and land management agencies to the possibility that Red Flag conditions may exist beyond the first forecast period (12 hours). The watch is issued generally 12 to 48 hours in advance of the expected conditions, but can be issued up to 72 hours in advance if the NWS agency is reasonably confident. The term "Fire Weather Watch" is headlined in the routine forecast and issued as a product. That watch then remains in effect until it expires, is canceled, or upgraded to a Red Flag Warning.
A Red Flag Warning, also known as a Fire Weather Warning is a warning issued to inform area firefighting and land management agencies that conditions are ideal for wildland fire ignition, and rapid propagation. To the public, a Red Flag Warning means high fire danger with increased probability of a quickly spreading vegetation fire in the area within 24 hours.
A Fire Warning is a warning issued by civil authorities in the United States to inform the public of major, uncontrolled fires (usually wildfires) threatening populated areas and/or major roadways. A fire warning will generally include information on the location and movement of the fire, evacuation instructions, and shelter locations.