A wildfire can accelerate from a smouldering patch to 100 km/h in minutes. Entire hillsides ignite before the first tanker plane arrives. This is not bad luck — it is physics. Here is exactly how a fire front works, and how to read the live NASA fire data burning on the globe right now.
NASA FIRMS — ACTIVE FIRE DETECTIONS — MODIS & VIIRS SATELLITES
LIVE DATA ACTIVE
The dots of light on the globe above are not icons or symbols. Each one is a thermal anomaly detected by a satellite passing overhead — a patch of ground hot enough to register against the surrounding landscape on NASA's MODIS or VIIRS infrared sensors. Some are agricultural burns. Many are wildfires moving through vegetation at speeds that make evacuation a race with minutes to spare. Understanding why fire moves the way it does is not just science — for millions of people living in fire-prone regions, it is survival knowledge.
Modern wildfire science has transformed what was once considered unpredictable into something that can be modelled, forecast, and — in the best circumstances — anticipated. The physics of fire spread follows clear principles. The variables are well understood. What makes wildfires lethal is not mystery; it is the convergence of those variables in combinations that overwhelm human response capacity.
THE FIRE TRIANGLE — THREE THINGS EVERY FIRE NEEDS
Every wildfire requires exactly three inputs to ignite and sustain itself. Remove any one of them and the fire dies. Understanding each input is the foundation of both fire behaviour prediction and fire suppression strategy.
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FUEL
Dry vegetation — grass, shrub, timber, leaf litter, duff. Fuel load (mass per area) and fuel moisture content determine how readily a fire starts and how intensely it burns. Below 25% moisture, most vegetation ignites readily. Below 10%, fire spread is explosive.
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WIND & OXYGEN
Wind supplies oxygen, dries fuel ahead of the fire front, bends flames into unburned fuel, and carries burning embers kilometres ahead of the main fire. Even a 10 km/h increase in wind speed can double fire spread rate. Wind direction shifts are the leading cause of firefighter fatalities.
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HEAT
A wildfire is self-sustaining because combustion generates more heat than is needed to ignite the next layer of fuel. Radiant heat pre-heats and desiccates vegetation ahead of the fire front. Convective heat rises and can ignite canopy above the ground-level flames — the transition to crown fire.
THE THREE HEAT TRANSFER MECHANISMS
Fire does not simply "spread" — it ignites new fuel through three distinct physical mechanisms, each dominant in different fire scenarios. Understanding which mechanism is driving spread determines the correct suppression strategy and evacuation timeline.
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RADIATION — THE INVISIBLE HEAT FRONT
The flame zone emits intense thermal radiation — infrared energy — that propagates through air and pre-heats vegetation ahead of the fire front without any physical contact. At a metre from a flame front burning at 800°C, radiant heat flux is roughly 25–50 kW/m² — comparable to standing directly in front of a large industrial furnace. Vegetation exposed to this flux desiccates rapidly and begins pyrolysing (breaking down chemically) before the flames arrive, dramatically reducing the ignition time when they do. Radiation is the dominant spread mechanism in low-wind grass fires.
Hot combustion gases rise in a convective column above the fire — the thermal plume visible as smoke and heat shimmer. This rising air draws cool air in at the base (entrainment), accelerating combustion. In steep terrain, convection drives the most dangerous fire behaviour: upslope runs. Flames burning uphill are tilted into the unburned slope above, preheating fuel ahead while radiating heat directly into the slope face. Fire spread rate doubles approximately every 10° of slope increase. A fire at 30° slope spreads roughly 8× faster than on flat ground.
The most unpredictable and dangerous spread mechanism. Burning embers — firebrands — are lofted by the convective column and carried downwind by surface winds. They land ahead of the fire front and ignite spot fires, which can merge with the main fire or create entirely new fire fronts behind evacuation lines. In eucalyptus forests, firebrands can travel up to 40 km ahead of the fire front. During Australia's 2019–20 Black Summer fires, spotting distances of 30+ km were recorded. Spotting is the mechanism that makes fire "jump" roads, firebreaks, rivers, and defensible space and is the leading cause of suburban structure losses in wildland-urban interface fires.
▸ MAX RANGE: 40 KM · DEFEATS FIREBREAKS · PRIMARY CAUSE OF STRUCTURE LOSS IN WUI
FIRE TYPES AND SPREAD SPEEDS
Not all wildfires behave the same way. The type of fire is determined primarily by the vertical layer of vegetation in which combustion is occurring — from slow smouldering underground to explosive crown fires burning through the forest canopy at speeds exceeding 100 km/h.
FIRE TYPE
TYPICAL SPREAD RATE
RELATIVE SPEED
DOMINANT FUEL
SUPPRESSION
GROUND FIRE
<1 m/hour
Crawling
Peat, duff, humus
Water injection, excavation
SURFACE FIRE
1–50 m/min
Walking pace
Grass, litter, low shrub
Direct attack viable
RUNNING GRASS FIRE
50–200 m/min
Fast run
Dry grassland
Aerial only under wind
PASSIVE CROWN FIRE
100–400 m/min
Cycling speed
Forest canopy + surface
Indirect attack · backfire
ACTIVE CROWN FIRE
300–1,000 m/min
Car on highway
Closed canopy forest
Essentially unsuppressible
FIRESTORM
>1,000 m/min
Uncontrollable
Everything
No suppression possible — evacuate
WIND AND TOPOGRAPHY — THE MULTIPLIERS
Of all the variables that determine fire behaviour, wind and topography are the most operationally critical — because they change fastest and their interaction creates the conditions for catastrophic blowups. Fire managers spend more time forecasting wind than any other variable.
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FOEHN WINDS — THE GLOBAL COMMON FACTOR
The most dangerous wildfire conditions worldwide are driven by foehn-type winds — dry, warm, fast winds that develop when air descends the lee side of a mountain range. California's Santa Ana winds, Australia's "northerlies," Spain's Tramontane, Greece's Foehn — all the same physics, different names. They dry vegetation to dangerous moisture levels and accelerate fires to extreme rates simultaneously.
▸ SANTA ANA · DIABLO · TRAMONTANE · NORTHERLIES
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TERRAIN CHANNELLING
Valleys, canyons, and chimneys (steep, narrow drainages) funnel and accelerate wind to speeds far above the ambient. Fire burning upslope through a canyon can experience local wind speeds 3–5× greater than the open terrain. The 2018 Camp Fire (Paradise, California) spread 20,000 acres in the first 3 hours — driven by 50–70 mph Diablo wind gusts channelled through the Feather River Canyon.
▸ CANYON RUNS · CHIMNEY EFFECT · CAMP FIRE 2018
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WIND DIRECTION SHIFTS
The most lethal single event in wildfire operations. A fire's rear becomes its flank becomes its head instantaneously when wind shifts 90°. Fire crews and aircraft working the flank of a fire are suddenly in front of an advancing head. The 1994 South Canyon Fire (Colorado) killed 14 firefighters in under 3 minutes when a thunderstorm outflow shifted winds by 180° on a fire they considered controlled.
▸ LEADING CAUSE OF FIREFIGHTER FATALITY · SOUTH CANYON 1994
HOW NASA DETECTS FIRES FROM ORBIT
The dots on Pandita Data's wildfire globe come directly from NASA's Fire Information for Resource Management System (FIRMS) — a near-real-time fire detection system built on data from two satellite-borne sensors that scan the entire Earth's surface multiple times per day.
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MODIS — MODERATE RESOLUTION IMAGING SPECTRORADIOMETER
Aboard NASA's Terra and Aqua satellites. Scans the entire Earth's surface twice per day — once in the morning (Terra) and once in the afternoon (Aqua). Spatial resolution: 1 km per pixel in the thermal infrared bands used for fire detection. Detects fires larger than approximately 50–100 m across under good observation conditions. Uses bands 21 and 22 (3.96 μm) for fire detection, comparing observed brightness temperature against background to identify thermal anomalies. Has been operational since 1999 — providing the longest continuous global fire record from space.
▸ RESOLUTION: 1 KM · 2 PASSES/DAY · OPERATIONAL SINCE 1999
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VIIRS — VISIBLE INFRARED IMAGING RADIOMETER SUITE
The successor sensor, aboard Suomi NPP and NOAA-20 satellites. Key improvement over MODIS: 375-metre spatial resolution in fire detection bands — detecting fires as small as a few hectares. Higher sensitivity means it detects smaller, cooler fires missed by MODIS. Passes at different times, providing 4+ observations per day globally when combined with the two MODIS platforms. The combination of MODIS and VIIRS gives near-real-time coverage with detection latency typically under 3 hours from ignition for most significant fires.
NASA FIRMS processes raw satellite data and publishes fire detection shapefiles and GeoJSON feeds updated every 10 minutes as new satellite passes are processed. Each detection record includes: latitude, longitude, acquisition time, satellite, instrument, confidence level (low/nominal/high), fire radiative power (FRP in MW — a measure of fire intensity), and daynight flag. Pandita Data's 3D wildfire simulation ingests this feed and renders each detection as a point on the WebGL globe, scaled by FRP and coloured by recency. A large bright dot on the globe is a high-confidence detection with high fire radiative power — a big, hot, actively burning fire detected in the last satellite pass.
▸ NASA FIRMS → GEOJSON → PANDITA DATA → 3D GLOBE · LATENCY: <3 HOURS
// FIRE RADIATIVE POWER — WHAT THE DOT SIZE MEANS
Fire Radiative Power (FRP) is measured in megawatts — the total thermal energy being released per second by the fire at the time of satellite overpass. A single VIIRS pixel with FRP of 1,000 MW is releasing as much energy as a large nuclear power plant's full output, continuously, as thermal radiation into the atmosphere. The largest fire complexes in Australia's Black Summer 2019–20 produced FRP detections exceeding 100,000 MW per pixel cluster. On Pandita Data's globe, dot size is scaled proportionally to FRP — the largest dots are the hottest, most intensely burning fires detected in the current satellite pass cycle.
// THE WILDLAND-URBAN INTERFACE — WHY FIRES ARE KILLING MORE PEOPLE
The most dangerous wildfire trend of the 21st century is not fire behaviour — it is where people are building homes. The wildland-urban interface (WUI) — the zone where residential development meets fire-prone vegetation — has expanded dramatically across California, Australia, southern Europe, and South Africa as populations spread into formerly uninhabited fire-prone landscapes. In the US, over 46 million homes now sit in the WUI. These homes are typically built with wood and asphalt shingles — highly combustible materials — and often surrounded by ornamental landscaping that is not fire-resistant.
The 2018 Camp Fire (Paradise, CA) destroyed 18,804 structures and killed 85 people — the deadliest US wildfire in a century. Fire spread through suburban streets at over 80 football fields per minute. Most deaths occurred in vehicles as people tried to evacuate. The fire's behaviour was not unprecedented for the vegetation and weather conditions — what was unprecedented was the density of structures and people in its path.
// LIVE GLOBAL WILDFIRE MAP — NASA FIRMS · MODIS + VIIRS
LIVE — NASA SATELLITE DATA
DRAG TO ROTATE · SCROLL TO ZOOM · DOT SIZE = FIRE RADIATIVE POWER
Wildfire is not uniformly distributed across the globe — it is concentrated in regions where climate, vegetation type, and human ignition patterns converge to create predictable seasonal fire cycles. The globe above shows these patterns in real time.
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TROPICAL AFRICA & SAVANNA
By area burned, sub-Saharan African savanna is the world's largest wildfire region — accounting for roughly 70% of global area burned annually. The fires are primarily agricultural and land-management burns set by farmers, producing vast continuous fire fronts across the dry season. On the globe, Africa is by far the most active region for most of the year.
▸ 70% OF GLOBAL AREA BURNED · PRIMARILY AGRICULTURAL BURNS
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WESTERN NORTH AMERICA
California, Oregon, Washington, British Columbia, and Alberta experience severe fire seasons driven by prolonged drought, fuel accumulation from decades of fire suppression, and foehn-type winds. Climate change has extended the fire season from roughly 5 months to year-round in many areas. The Camp Fire (2018), Dixie Fire (2021), and Oak Fire (2022) represent a new norm.
▸ EXTENDED SEASON · SANTA ANA / DIABLO WINDS · FUEL ACCUMULATION
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AUSTRALIA
Australia's eucalyptus forests are among the most fire-adapted and fire-dangerous ecosystems on Earth. Eucalyptus trees shed bark ribbons and leaves that accumulate as volatile fuels; their leaves contain flammable oils that vaporise ahead of the fire front. The 2019–20 Black Summer burned 18.6 million hectares — an area larger than Syria — and generated pyroconvective thunderstorms that created their own weather.
▸ 18.6M HA IN 2019–20 · EUCALYPTUS OIL · PYROCONVECTION
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MEDITERRANEAN EUROPE
Greece, Portugal, Spain, and Italy experience severe fire seasons driven by summer drought, rural depopulation (leaving unmanaged fire-prone vegetation), and increasingly extreme heat events. The 2021 Greek fires burned 125,000 hectares on Evia island in a single week. Portugal's 2017 Pedrógão Grande fire killed 64 people in a single night, many trapped in their cars.
Once you understand what each element represents, the wildfire globe becomes an immediate, intuitive picture of global fire activity. Every detail is meaningful:
// COMPLETE READING GUIDE — EVERY ELEMENT DECODED
Dot position: The geographic centre of a fire detection pixel — either 1 km² (MODIS) or 375 m² (VIIRS). A cluster of adjacent dots is one large fire seen across multiple pixels.
Dot size: Proportional to Fire Radiative Power (FRP) in megawatts. Large dots = intense, high-energy fires. Small dots = low-intensity fires or cool smouldering.
Dot colour / brightness: Recency. Brighter or more saturated dots are more recent detections — within the last satellite pass. Dimmer dots are older detections from earlier passes that have not yet been confirmed extinguished.
Africa concentration: The dense field of dots across sub-Saharan Africa at almost any time of year reflects the massive seasonal burning cycle that dominates the continent's fire calendar — not a crisis, but a predictable pattern.
Absence of dots: Does not mean no fires. It means no satellite has passed over that location recently enough to detect them, or that fire intensity is below the detection threshold, or that cloud cover blocked the thermal infrared sensor. Detection gaps over areas with persistent cloud cover are a significant limitation of satellite fire monitoring.