How does SignalGuard detect wildfires?

SignalGuard queries the NASA FIRMS (Fire Information for Resource Management System) public API for VIIRS and MODIS thermal anomaly detections within 200 miles of the venue. Each detection includes lat/lon, confidence, and detection time — typically within 3 hours of the satellite pass.

What wildfire conditions escalate the signal?

Active detections within 25 miles escalate to MEDIUM. Within 5 miles, or active wildfires in the venue's county per Cal Fire / state agency APIs, escalate to HIGH. Wildfires beyond 25 miles inform the Air Quality signal but don't escalate Wildfires alone.

Does SignalGuard see prescribed burns?

FIRMS does not differentiate prescribed burns from wildfires in raw thermal data. SignalGuard cross-references InciWeb and CAL FIRE incident feeds when available to label prescribed burns, so they don't drive false escalations.

Wildfire Monitoring for Outdoor Events

Wildfire smoke monitoring for events is no longer a Western-states concern. The June 2023 Canadian wildfires turned New York City's AQI to 484 during the daytime — within 24 hours of the smoke arriving, multiple outdoor concerts in the tri-state area cancelled or moved indoors. SignalGuard's wildfire signal pulls satellite-detected hotspots in near-real-time so your team sees the fire that will become tomorrow's smoke event today.

What this signal monitors

The Wildfires signal reports active satellite-detected hotspots within a configurable radius (default 200 km) of the venue. Each hotspot includes its distance, Fire Radiative Power (FRP, in megawatts — a proxy for how hot the fire is burning), confidence score, and acquisition date/time. The signal answers "are there fires near my event?" with a count and a worst-case proximity, then escalates the threat level based on how close they are and how many.

Data sources

SignalGuard's firmsClient.js calls the NASA FIRMS area API using VIIRS S-NPP near-real-time detections — the higher-resolution satellite source (375 m pixels) compared to the legacy MODIS feed. FIRMS is free, requires a (free, instant) MAP_KEY from NASA, and is the same dataset Cal Fire, USFS, and most state emergency operations centers consume for the satellite layer of their common operating picture. We pull the last 24 hours of detections by default and filter the response to a haversine-distance radius around the venue (the bounding box is square; the radius trims it to a circle).

How SignalGuard scores severity

Per-hotspot severity is distance-based: any hotspot inside 10 km of the venue is critical; 10–50 km is high; 50–100 km is medium; everything else inside the search radius is low. The overall level escalates further when count is high — 5 or more detected fires within the radius bumps the overall to high even if no single fire is close, because smoke load is cumulative and a fire complex 80 km upwind on a windy day is operationally identical to one at 40 km on a calm day. The signal does not currently fuse wind direction (that's surfaced separately on the weather card), so we recommend operators read the two signals together when smoke routing matters.

Use cases for event security

48-hour smoke forecast. A cluster of 6 hotspots 60–90 km upwind of the venue plus a forecast westerly wind on event day = a near-certain AQI degradation. Production publishes the contingency posture before tickets-on-sale stop.
Show-day shelter calculus. A critical hotspot inside 10 km (rare but real for venues in foothills) triggers an immediate evacuation rehearsal with the venue ops manager and the local IC, well before AQI even spikes.
Insurance and contract trigger. Many performer riders and event-cancellation insurance policies define "wildfire" using satellite-detection proximity. The FIRMS feed is the same source insurers reference — having it surfaced on your operational dashboard means no time wasted retrieving evidence when a claim or invocation is needed.

Pairs well with

Air quality monitoring — the downstream effect on breathable air at the venue.
Weather monitoring — wind direction and forecast precipitation either advect smoke in or scrub it out.
SPC severe weather forecasts — dry-lightning days are wildfire-start days.

Premium upgrade path

For sub-3-hour latency on hotspot detection and higher confidence on small-fire detection, BYOK Planet Labs imagery or Maxar's WildFire Sentinel feed on the Integrations page. Tomorrow.io's wildfire risk overlay adds spread-modeled forecasts. For California events specifically, Cal Fire's incident feed is a free supplement with named-incident-level reporting. NASA FIRMS itself is best-in-class for free global coverage.

Frequently asked questions

How quickly does NASA FIRMS detect a new wildfire? VIIRS overpasses occur roughly every 12 hours per satellite; with both Suomi NPP and NOAA-20/21 in service, typical latency from detection to FIRMS publication is 3 hours. SignalGuard's 15-minute cache means a fire detected at 14:00 UTC will appear on your dashboard by 17:15 UTC at the latest.

Does SignalGuard predict where smoke will travel? Hotspot detection is geographic, not predictive. Pair the wildfire signal with the Weather monitoring card's wind forecast for directional context, or BYOK a smoke-dispersion provider on /integrations.

What's the difference between MODIS and VIIRS in FIRMS? VIIRS has 375-meter pixels (vs. MODIS's 1 km) and lower minimum-detectable-fire thresholds. SignalGuard uses VIIRS S-NPP by default for higher precision near venues.

Can FIRMS detect fires under heavy cloud cover? No — VIIRS is a thermal-infrared sensor and heavy cloud will block detection. This is the main reason SignalGuard surfaces hotspot count as a confidence indicator and recommends pairing with air quality data.

Is the wildfire signal available for international venues? Yes — NASA FIRMS is global. See SignalGuard docs for venue-specific configuration.

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