
Heat Compass
Heat flags, WBGT, hydration
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What's New in Heat Compass
1.0.1
August 10, 2026
Corrected WBGT accuracy. Heat Compass was under-reading WBGT in hot, dry, sunny conditions - the exact weather where heat is most dangerous. In one Sacramento reading it showed a Green flag where a WBGT meter reads Black. If you used Heat Compass this summer in dry heat, your flag may have been too low. The calculation now uses the Liljegren (2008) model, the method NIOSH references for deriving WBGT from weather data. It solves the natural wet bulb and black globe from full energy balances instead of estimating them, and uses exact sun geometry from your local forecast. Also in this release: - Hydration guidance no longer contradicts itself. The hourly target now respects what the flag and your workload require, and never falls below it because your daily total looks on track. - Hydration needs follow the flag. They previously opened at a placeholder value and only moved when the weather changed. - The flag now refreshes on its own every 10 minutes and when you reopen the app, instead of waiting for you to pull to refresh. - Chart legend uses the same White/Green/Yellow/Red/Black names as the rest of the app. "SAFE" is gone - a green flag is low risk, not safe. - Removed the pavement heat checker.
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