Heat Index: Get Heat Alerts

How dangerous is the heat right now — and when will it be safe? Heat Index answers that the moment you open it, with the same number your local forecasters use.

THE NUMBER YOU CAN TRUST We compute the official NWS heat index — the real "feels like" combining heat and humidity — using the published National Weather Service formula, from Apple Weather data. Every reading shows its source, observation time, and location, so you can check our work. No mystery numbers, no forecast pretending to be current conditions.

NEVER A BLANK SCREEN Lost signal on a remote worksite? The app keeps your last reading with a clear timestamp instead of an error page. Built for the exact moment other heat apps fail: the hottest day of the year.

KNOW WHEN IT'S SAFE • A color-coded risk level with plain-language guidance — from "normal precautions" to "avoid outdoor exertion" • An hourly danger timeline that spots your next safe window: "Safe for exertion after 7 PM" • A daily outlook to plan work, training, and family time around the heat

SUN OR SHADE — YOUR REAL CONDITIONS The standard heat index assumes shade. Working or training in direct sun can feel up to 15°F hotter. Flip to Full Sun mode and the number adjusts using sun angle and cloud cover.

ALERTS BEFORE IT GETS DANGEROUS • Official government heat warnings for your saved locations • Your own threshold: "tell me when the heat index passes 100°" — set it to match your company's heat policy or your doctor's advice • An optional morning briefing: today's peak, risk level, and when it hits

BUILT FOR PEOPLE WHO WORK AND TRAIN OUTDOORS Estimated WBGT (wet bulb globe temperature) with standard activity flags for athletes, coaches, and safety managers — honestly labeled as an estimate, computed correctly. Plus a plain-English heat illness guide: symptoms, first aid, and work/rest guidance you can read offline.

WORKS ANYWHERE IN THE WORLD US, UK, Australia, Canada — anywhere Apple Weather reaches. Search any city or postcode, or enter exact coordinates for remote sites. No location permission required.

PRIVATE BY DESIGN No accounts. No ads. No tracking. Your location never leaves your device except to fetch weather from Apple Weather. Ever.

FREE VS PRO The current heat index, risk level, hourly outlook, government alerts, sun mode, a personal threshold alert, and the safety guide are free — the core reading is never paywalled. Heat Index Pro adds the full 48-hour timeline, 7-day outlook, estimated WBGT, up to 10 saved locations with per-location alerts, and the morning briefing.

Pro is an auto-renewing subscription (monthly or yearly, with a free trial on the yearly plan). Payment is charged to your Apple Account, and subscriptions renew automatically unless cancelled at least 24 hours before the end of the period. Manage or cancel anytime in Settings.

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Weather data provided by Apple Weather.