Heat Journal
Heat Journal app icon

Time the heat.
Watch your heart.

A sauna timer built for Apple Watch. Start from your wrist, see your heart rate live, and get a tap before the watch itself gets too hot.

Coming to the App Store
Heat Journal on Apple Watch showing the session timer, heart rate and time remaining inside a progress ring
On the wrist: timer, heart rate, target
Heat Journal on iPhone showing session history with duration, heart rate and weight
On the phone: every session, synced

Made for the sauna, not the gym

Watch-first timer

A big, readable chrono with a progress ring toward your target. Runs in the background so the alert fires even with the wrist down.

Live heart rate

Average and peak heart rate for every session, straight from the watch's sensor.

Overheat warning

Apple Watch has limits too. Heat Journal taps you when the watch is getting too hot, so you can cool it before it shuts down.

Weight tracking

Log your weight after a session, in kilograms or pounds, from either device. See both units at a glance.

Wet-hands controls

Double Tap starts, pauses and resumes. On Apple Watch Ultra, the Action button does the same.

Your data stays yours

Sessions live on your devices and sync between your own iPhone and Apple Watch. No account, no server.

Requirements

Apple Watch with watchOS 11 or later, paired with an iPhone running iOS 18 or later. Heart rate requires permission to read from Health; everything else works without it.