WetBulbTracker: WBGT Safety

The thermometer measures the air. Your body is also dealing with the humidity, the wind and the sun. Two places can both read 90°F and be very different places to work, train or walk a dog. WetBulbTracker estimates heat stress (WBGT, wet-bulb globe temperature) for any place on Earth. WBGT is the measure that militaries, athletic associations and occupational-safety standards use. It accounts for humidity, wind, cloud cover and direct sun, which is why it so often disagrees with the number on a weather app, and why the disagreement matters. ON IPHONE AND IPAD • Home Screen and Lock Screen widgets: the estimated heat stress where you are, or at the last place you opened when location is off, with the hours ahead on the Home Screen • With no connection, the app lists the last readings it fetched for your places, each with its time NO ACCOUNT NEEDED • Heat stress for any place, in sun and in shade • Plain-language guidance: what to change, not just a number • A map with six ways to read the heat, through the next 24 hours • A pavement check for paws, including the heat asphalt still holds after sunset • "Your risk": an optional personal read for age, exertion, heat adaptation and health sensitivities • Work/rest guidance for outdoor crews, and athletics and tactical pages, each naming whose guidance it is • What each state's school sports association says about heat (below) • City guides for 176 US metros • Today's report as a link, image or PDF, and any report someone shares with you • A WBGT calculator and plain-language heat guides WITH AN ACCOUNT • Heat alerts as notifications on your iPhone or iPad, up to a day ahead at a level you choose, with quiet hours • Saved places, the same in the app and on the website STATE HEAT POLICIES FOR SCHOOL SPORTS Most state high school athletic associations publish a heat policy. Each state and DC has a page on what its association says about heat: • A plain one-line summary • Whether its document reads as a requirement or as guidance, or sets no statewide WBGT rule • Its heat table, where there is one for the whole state • Other points from what it publishes, credited to it • A link to its document, where we could confirm one • The date we last checked it, where we have one The policy card links to your state's page. The pages summarize each document and are not legal advice: the policy your school, district or league has adopted is the one that applies. HOW ACCURATE IS IT? We publish that at wetbulbtracker.com/validation: our WBGT against the U.S. National Weather Service's own published WBGT, refreshed as new forecasts arrive. Both are modeled rather than measured, and we say so on the page. A conditions-based correction cut our error by about a third on days the model had never seen. The method is at wetbulbtracker.com/methodology. We would rather show you the error bars than claim we do not have any. WHAT THIS IS NOT Our numbers are modeled from gridded weather data, not measured at your location by an instrument. Where a standard, contract or policy calls for a reading from an on-site instrument, that instrument is the one that governs. Use this to plan the day, pick the window and know what to expect before you get there. This app is informational. It is not a medical device and does not diagnose, treat, cure, or prevent any medical condition. Consult a healthcare professional for medical advice, diagnosis, or treatment. It is not a substitute for official heat warnings from your weather service. Always follow your local authorities. WBGT is computed by the Liljegren (2008) method from Open-Meteo data.