Journal

Notes on heat, cold and honest tracking.

Longer pieces on the thinking behind Hormetic: what a sauna, a plunge or a soak can and can’t tell you, and how the app estimates each one.

September 28, 2026

Does Apple Watch measure water temperature?

See which Apple Watch models measure water temperature, how Hormetic uses it for cold plunges, and what the app labels measured, entered and Estimated.