Also in: Disaster Response and Recovery
Heat Stress (WBGT and Heat Index)
Heat index, WBGT estimate, and OSHA-style work / rest cycle.
Example
You enter
- Dry-bulb temp (°F) 95
- Relative humidity (%) 60
- Direct sun exposure false
You get
- Heat index 113.1 F
Checked against published worked examples from: NWS.
Details, formula, and sources
Formula or tableNWS Heat Index = polynomial of T_db (°F) and RH (%) (Steadman regression); WBGT approximated as 0.7 Twb + 0.2 Tg + 0.1 Tdb (Twb ~ T - 30(1 - RH), Tg = T + 5, or + 15 in sun); work/rest from WBGT bands 82 / 86 / 90 F.
Source and editionNWS Heat Index polynomial by name; OSHA Heat Illness Prevention work-rest table by name.
Free accessFree at weather.gov/safety/heat-index and osha.gov/heat-exposure.
What governsEstimate. AHJ and licensed professional govern.
API field namesT_F, RH_percent, solar, heat_index_F
- Acclimatization not modeledOSHA Heat Illness Prevention