HeatRisk | Extreme Heat Health Risk

Where is dangerous heat overlapping with large and socially vulnerable populations?

Data health

Waiting for live sources…

How to read this map

Hazard / signal: Extreme-heat conditions
Exposure: Population exposure
Consequence / vulnerability: Social vulnerability / health sensitivity

Official/source values remain distinct from MitchellCo derived screening scores or estimates. Derived values are for prioritization and interpretation, not official warnings or predictions.

Map layers & legend

NWS HeatRisk forecastExperimental NWS 24-hour health-impact forecast, categories 0 to 4. Updated hourly. NWS heat alertsOfficial Extreme Heat Warnings/Watches and Heat Advisories. CDC county vulnerability2022 SVI plus population, age 65+, disability, poverty, and population density.

HeatRisk 0: little to no risk

HeatRisk 1: minor

HeatRisk 2: moderate

HeatRisk 3: major

HeatRisk 4: extreme

What this map combines

Hazard: NWS HeatRisk and official heat alerts. Exposure: county population and population density. Vulnerability: CDC/ATSDR Social Vulnerability Index, age 65+, disability, and poverty context. Click a county for details; click anywhere else on the map to sample the current HeatRisk category.

No second composite score. NWS HeatRisk already incorporates CDC health-impact information. Adding SVI again into a derived score would double-count vulnerability and make the result look more precise than the inputs support. This map keeps the official NWS hazard value separate from CDC exposure/vulnerability context.

Live status

NWS HeatRisk—

NWS heat alerts—

CDC counties—

HeatRisk: not loaded

Alerts: not loaded

SVI: not loaded

Refresh / vintage

NWS HeatRisk is refreshed hourly, matching the upstream hourly update cadence. NWS alerts are checked every 5 minutes, far slower than the NWS maximum recommended request frequency. CDC SVI is the 2022 national county dataset and is loaded once per selected state, then cached for the session. Polling pauses while the tab is hidden or the browser is offline, and requests are never overlapped.

Sources

NOAA/NWS HeatRisk Image Service
NWS HeatRisk ImageServer
Experimental 24-hour heat-health risk guidance, category 0 to 4. Time-enabled; source states hourly updates. Anonymous ArcGIS image/identify service; no key/account.

National Weather Service Alerts API
NWS alerts documentation
Official active Extreme Heat Warning, Extreme Heat Watch, and Heat Advisory products. Legacy Excessive Heat Warning/Watch names are also recognized for compatibility. Anonymous public API; no key/account.

CDC/ATSDR Social Vulnerability Index 2022
CDC OneMap county FeatureServer
County SVI rank and ACS-derived demographic/exposure fields. 2022 vintage; static during the session. Anonymous ArcGIS FeatureServer; no key/account.

Preferred layers omitted: cooling centers and hospitals are not shown because no single authoritative national browser-ready source with consistent current coverage was verified for this build. Urban tree canopy/imperviousness are also omitted rather than mixing in a large static raster whose national browser delivery path was not verified strongly enough for this run.

Basemaps: USGS The National Map, OpenStreetMap, OpenTopoMap, and NASA EOSDIS GIBS. Community tile services retain their own attribution and usage policies.