Wet Bulb Temperature Tracker
WBGT Humid heat risk
Free · In‑App Purchases · Designed for iPhone. Not verified for macOS.
Wet Bulb Tracker shows Wet Bulb and WBGT Outdoor temperatures, daily timelines and Alerts for rising temperatures — now on Apple Watch too.
The number of high Wet Bulb temperature days is rising each year, and this free Wet Bulb Tracker keeps you informed for your health and safety, so you can plan your activities for the day, at work or with family.
Wet Bulb Temperatures measure humid-heat conditions, not just air temperature. That temperature tells you how well your body can cool through sweat evaporation. With the Wet Bulb temperature, you can track how warm your body will get if you don't take steps to cool when outdoors and active. It helps stay safe from Heat Stress.
We feel comfortable at typically 25°C / 77°F or below, whereas our core body temperature is around 35–36°C / 95–96.8°F. A Wet Bulb higher than 30°C / 86°F quickly feels uncomfortable as cooling through sweat becomes difficult. Though people in warmer climates are acclimatised to higher wet bulbs, as Wet Bulb temperatures approach body temperature, serious health risks emerge—especially for those active outdoors through work, play, or travel.
Wet Bulb Tracker puts that number on your screen for wherever you are, right now and for the hours ahead.
TWO RELATED READINGS FROM WEATHER DATA
Wet Bulb is usually measured using physical instruments in the field, but is also approximated with math.
• Wet Bulb — worked out from air temperature and humidity using Stull's formula. This is a convenient reference to get a general sense of the heat risk.
• Wet Bulb Globe (WBGT) — is for outdoors, and also uses sun and wind in calculating heat risk. This is the one that matters if you're working, training, or walking outside.
SEE A WHOLE DAY'S TIMELINE
View an hourly timeline of each day's Wet Bulb temperature, coloured by safety level, showing how humid-heat builds and fades. Drag the marker across the day and the Wet Bulb and Weather readings above it change. Hours likely to see rain show a smaller bar in the block, giving the percentage chance of rain in your area. Rain and Wet Bulb can often be independent in how cool you feel.
KNOW WHAT TO DO
Every risk level comes with basic but handy Guidance: how long it's reasonable to stay out, what to watch for, and when to take breaks. Reference links in the About page cover the Wet Bulb thresholds used by militaries, occupational safety bodies, and national weather services around the world, with links to the underlying research.
HEAT ALERTS
Choose to enable Alerts. Get notified when outdoor conditions go higher, wherever you are. Silence alerts that would arrive between 10 PM and 7 AM, so you see them on the lock screen in the morning.
WORK IT OUT - GET AN UNDERSTANDING
The Calc tab lets you slide in any air temperature, humidity, wind speed, and solar radiation and watch both readings respond. Useful for teaching the concept or calculating from data.
FREE WET BULB TRACKER: View both the Wet Bulb and WBGT readings, today's full hourly timeline with chance of rain, get 'Rising Wet Bulb' alerts, Heat care guidance, the WBGT calculator, and city search for anywhere in the world.
WETBULB+ SUPPORTS DEVELOPMENT OF THIS FREE APP
An optional upgrade, as a yearly subscription or a single one-time purchase:
• Six-day forecast timelines, so you can pick the safe days or times when planning activity
• An Apple Watch app showing the current reading, safety level, and the day's timeline on your wrist
• A Home Screen widget showing the current reading and safety level
• Apple Weather as your data source, for more precise local data
Wet Bulb Tracker is an informational tool. It is not a substitute for official weather warnings, workplace safety guidance, or medical advice.
The WetBulb+ subscription renews yearly unless cancelled at least 24 hours before the period ends. Payment is charged to your Apple Account, and you can manage or cancel in your Apple Account settings.
Terms of Use: https://www.apple.com/legal/internet-services/itunes/dev/stdeula/
Privacy Policy: https://tulkitdesign.com/wetbulb-tracker-privacy-policy/
Ratings & Reviews
APPLE WATCH APP
WetBulb+ now puts the Alert Notifications and Days Timeline on your wrist: the current Wet Bulb Globe temperature, and the day's timeline highlighted hourly by safety level.
A WIDER HOME SCREEN WIDGET
A new medium widget shows the current level and reading with the sky, today's high and low, air temperature, humidity and the chance of rain — over the whole day's timeline.
CHANCE OF RAIN, FOR EVERYONE
The timeline now draws the chance of rain as a bar in each hour, and the reading lists it alongside air temperature and humidity — on the free tier as well as WetBulb+.
OPENS ON WET BULB GLOBE
App opens on the Wet Bulb Outdoor tab, which is the one that matters if you're working, training, or walking outside.
ALSO IN THIS VERSION
• The widget and watch keep the day's timeline through a day the app isn't opened.
• FAQ & Support link added to Settings.
• Clearer wording and layout on the WetBulb+ screen
• Calc lists Solar Radiation before Wind Speed, and its labels no longer get cut off in other languages.
• More of the app reads in your own language, including the About Wet Bulb screens.
The developer, Sameer Rajadnya, indicated that the app’s privacy practices may include handling of data as described below. For more information, see the developer’s privacy policy .
Data Not Linked to You
The following data may be collected but it is not linked to your identity:
- Purchases
- Location
Accessibility
The developer has not yet indicated which accessibility features this app supports. Learn More
Information
- Seller
- Sameer Rajadnya
- Size
- 15.4 MB
- Category
- Weather
- Compatibility
Requires iOS 18.0 or later.
- iPhone
Requires iOS 18.0 or later. - Mac
Requires macOS 15.0 or later and a Mac with Apple M1 chip or later. - Apple Vision
Requires visionOS 2.0 or later. - Apple Watch
Requires watchOS 11.0 or later.
- iPhone
- Languages
English and 6 more
- English, Arabic, Japanese, Korean, Simplified Chinese, Spanish, Traditional Chinese
- Age Rating
4+
- 4+
- In-App Purchases
Yes
- WetBulb+ One Time $9.99
- WetBulb+ Annual $2.99
- Copyright
- © 2026 TulKit Design
