What changed & when
Onset through peak
Baseline 2026-09-17 · onset 2026-10-01 · peak 2026-10-02 · latest 2026-10-08. Compound Atmospheric Trap (Detected by Isolation Forest).
Riyadh, Saudi Arabia
4.2 Million Citizens· Asia Metropolitan Baseline🤖 1 Compound Anomaly: Detected by Isolation Forest (Unsupervised ML)
Detected by Isolation Forest (Unsupervised ML)
Unusual multi-feature weather trap: elevated PM2.5 (151.8 µg/m³) + low humidity (13 %) is trapping ground-level emissions.
Gemini AI Synthesis & Plain-Language Summary
In plain English: Riyadh shows a rare Isolation Forest combination (elevated PM2.5 (151.8 µg/m³) + low humidity (13 %)). Separately, PM2.5 is 151.8 µg/m³, which is very unhealthy on the EPA scale and above the WHO 24-hour guideline of 15 µg/m³. The compound pattern is statistical; the particle reading is health-relevant — limit prolonged outdoor exertion.
Gemini may only interpret numbers already on this page. Chart annotations below are computed from the dated series (onset, peak, duration, latest vs baseline). Hypotheses are labeled and are not verified causes.
Conversational Telemetry Questions (8 Indicators)
Open-Meteo · CAMS · NASA FIRMS · click a chart for 30/60/90-day investigationWHO 24h guideline: 15 µg/m³. EPA band: Very Unhealthy. 30-day baseline 135.5 µg/m³. Statistical anomaly: no. CAMS ozone on this page is 24 µg/m³ CAMS O₃ (mass concentration, not station AQI). · Click for dated trend
elevated PM2.5 (151.8 µg/m³) + low humidity (13 %) · Click for dated trend
High today: 39.4°C. 30-day baseline 35.9°C. · Click for dated trend
Dry spell does not automatically mean drought. Baseline 0 mm. · Click for dated trend
Wind helps disperse ground-level pollutants. Click for the humidity trend versus other atmospheric measurements. · Click for dated trend
Sun protection recommended during midday hours.
Standard clear atmospheric line of sight.
Is soil moisture balanced?Root Zone
1%Saturation
Optimal range for local urban vegetation.
See This Change From Space
Travel through satellite observations to discover how this area has changed.
2026-10-08
Humidity 13 % · VIIRS true-color · MAIAC/MODIS aerosol
Current · T−1 · T−7 · T−14 · T−30 · NASA GIBS · five snapshots, not a 90-day scrub
Magnitude & spatial extent
Not measured yet
Open the What changed tab to compare baseline and peak pixels. This is a visual aid, not a land-cover map.
Scientific uncertainty
Unusual ≠ unsafe
NASA GIBS true-color is typically about one UTC day behind. Clouds, smoke, and missing tiles can hide the surface; they are not evidence that conditions are typical or safe. Pixel differencing is an unvalidated visual comparison (fixed 15% RGB delta and a brightness cloud heuristic). It is not environmental detection. Onset and peak dates come from the city's modeled Open-Meteo / CAMS series, not from the satellite pixels.
Observed: Riyadh has an active air statistical flag (Compound Atmospheric Trap (Detected by Isolation Forest)). Satellite lookback compares a pre-onset baseline on 2026-09-17 with peak 2026-10-02 and latest 2026-10-08. NASA GIBS layer: VIIRS_SNPP_CorrectedReflectance_TrueColor with MODIS_Terra_Aerosol. Unusual ≠ unsafe — a radar flag is not a health classification, and a visual delta is not a verified land-cover change product.
In the local news · Ground-Truthing via SerpApi
Real-time web corroborationNo geographically relevant reports from the last 14 days matched this event. Missing headlines are not evidence that conditions are normal or safe.
Modeled weather: Open-Meteo (ECMWF IFS / GFS blend). Modeled air: Open-Meteo Air Quality (Copernicus CAMS). Observed fire: NASA FIRMS VIIRS 375 m. Observation 2026-10-08T00:00:00Z. Pillar Compound Trap.