Bushfire glossary

What the terms on this site mean — the words used by Australian fire agencies and by the satellites the map is built from.

Satellite hotspot

A point where a satellite sensor detected strong heat. Most are bushfires or grassfires, but some are industrial heat, gas flares or agricultural burning. A hotspot is a detection, not a confirmed fire.

Fire Radiative Power (FRP)

How much heat a fire is giving off at the moment of detection, in megawatts (MW). Higher FRP means a more intense fire. Fires on the map are shaded by intensity using FRP.

Fire event

A group of nearby detections of the same fire, merged into one event with its own page, so repeated passes over a single fire are not counted as many fires.

VIIRS, MODIS and Himawari

The satellite instruments behind the detections. VIIRS (375 m) and MODIS (1 km) fly on polar orbits and pass a few times a day. Himawari is geostationary: lower resolution, but it watches continuously, which is why some Australian fires show up here very quickly.

Fire Danger Rating (AFDRS)

The Australian Fire Danger Rating System: Moderate, High, Extreme or Catastrophic, plus No Rating. It describes how dangerous a fire would be if one started today — not whether a fire is currently burning.

Total fire ban

A legal declaration for a fire district on a given day that prohibits lighting any fire in the open. It is issued separately from the fire danger rating, and the penalties are significant.

Warning levels

Australian fire agencies use three levels. Advice: a fire has started, no immediate danger. Watch and Act: conditions are changing, take action now. Emergency Warning: you are in danger and must act immediately.

Planned burn / hazard reduction

A fire deliberately lit by an agency under controlled conditions to reduce fuel. These appear as heat on satellite images and are shown separately so they are not mistaken for a bushfire.

Bushfire vs grassfire

A bushfire burns in forest or scrub and is usually slower but longer-lived. A grassfire burns in cured grass and can move much faster, though it passes more quickly.

LGA (council area)

Local Government Area — the council boundary used to group fires geographically. Australia has around 560 of them, and their boundaries come from the ABS ASGS.

Burnt area / fire boundary

The ground area a fire has burned, drawn as a polygon. Where an agency publishes boundaries they are shown; otherwise the map shows satellite detections only.

Active fire

A fire with recent satellite detections or an open official incident. A fire drops off the active list once detections stop or the agency closes the incident.