Terms of Use
Last updated: 2026-07-10
An informational tool, not a medical device
Swelter computes the published NWS heat index and shows an estimated WBGT value alongside public NWS risk bands and the 80°F/90°F trigger points from OSHA’s proposed heat rule. It does not diagnose, treat, or prevent any medical condition, and it does not guarantee anyone’s safety. In an emergency, call 911 or seek medical help.
No affiliation
Not affiliated with, endorsed by, or connected to OSHA, NIOSH, CDC, or the National Weather Service. Threshold values and guidance are based on their published public information.
WBGT is an estimate
The WBGT figure Swelter shows is a software estimate derived from available weather data. It is not a measurement from a physical black-globe thermometer and is not a substitute for an on-site WBGT meter where one is required.
Purchases
A one-time in-app purchase unlocks the WBGT estimate, the Home/Lock Screen widget, threshold alerts, and the private heat log with CSV export. Purchases are handled by Apple under the App Store terms; refunds are managed by Apple. This is a one-time purchase, not a subscription.
Acceptable use
The app and this website are for your personal use. You may not redistribute, resell, or scrape their content.
No warranty
Swelter is provided “as is.” While the heat-index formula is validated against the published NWS chart, weather data, WBGT estimates, and any referenced regulatory information can change or be delayed. Always confirm current requirements with the primary sources linked from our guides.