The best sauna and cold plunge tracker apps in 2026

This site belongs to Contrast, one of the nine apps below, so its entry deserves the most scepticism. Everything said about the other eight comes from their own App Store listings, checked on 2 October 2026. A listing is marketing copy and an app can do more than it says, so “not advertised” here means exactly that and no more.

The short version

The nine side by side

Ratings are the US App Store’s figures on 2 October 2026. Contrast was released on 26 September 2026 and had no ratings when this was written.

Contrast: rounds that start themselves

On an Apple Watch Ultra or Series 10 and later, getting into water starts a round, and the temperature the watch reads decides whether it counts as hot or cold. Time in the water is split into six temperature bands, from icy below 8 °C to very hot at 41 °C and above, with heart rate for every round. Sessions save to Apple Health as Cooldown workouts. Each computed number in the Analysis tab comes with its method, its limits and a label for how strong the evidence is.

A sauna round starts on a tap, because for most saunas the watch should stay outside (more on that below). On older watches every round starts on a tap, and with no watch at all a session can be logged on the iPhone afterwards. The free tier covers watch tracking, Apple Health and weekly totals; Contrast Pro adds full history, the charts and the full Analysis tab.

Not the pick for anyone who wants guided breathing, a community, Garmin or Android.

Ultra Plunge: the closest to Contrast

Ultra Plunge reads the same water temperature sensor and shows the reading live on the watch. In the sauna it goes further than Contrast, with an optional Bluetooth sensor that measures air temperature and humidity. It also has an AI coach running on a local model, guided breathing, streaks, widgets, Strava, and estimates of calories and sweat loss, and it covers cryotherapy, float tanks, red light and hyperbaric oxygen. Its listing does not say that rounds start on their own when you get in.

Not the pick for someone who wants a permanent free tier, or who would rather not see calorie estimates for time in the heat. Ultra Plunge and Contrast compared.

Plunge: if you own a Plunge tub

The official Plunge app runs Plunge’s own cold plunges and saunas. It sets the temperature, schedules sessions and switches the light, and it times sessions as well. It has an Apple Watch app and more ratings than any other plunge or sauna app here, which mostly reflects how many tubs Plunge has sold.

Not the pick for a barrel, a bath or another maker’s tub, since the listing ties it to Plunge hardware. Plunge and Contrast compared.

GoPolar: Garmin, red light and a community

GoPolar covers the widest range of anything here: cold plunges, cold showers, sauna, red light and hyperbaric oxygen. A session can carry its duration, temperature, heart rate, blood oxygen and a written reflection. It works with both Apple and Garmin watches, and it has a community, challenges, rewards and a library of tips.

Not the pick for measured water temperature; the listing describes temperature as something you log. GoPolar and Contrast compared.

HotLog: a detailed sauna journal

HotLog records sauna, steam, infrared and cold plunge sessions with the sauna type, temperature, humidity and duration, and it handles Aufguss sessions, which nothing else here mentions. It can save sessions to Apple Health as workouts. It is bought once rather than subscribed to, and it runs on iPhone.

Not the pick for timing rounds from the wrist or heart rate per round. HotLog and Contrast compared.

ThermaSesh: a plain watch timer

ThermaSesh is watch-first and short to describe. It times sessions on the Apple Watch, records time and heart rate through HealthKit, and keeps a list of sessions on the iPhone with notes and reminders.

Not the pick for water temperature or analysis, neither of which its listing advertises.

Shiver: the simplest cold log

Shiver is a cold plunge log and nothing more, and it says so with some pride. It has a timer with a goal, a grid of the days you plunged, a feed of past sessions, and charts of how often, how cold and how long. It works offline, keeps its data on the phone, needs no sign-up, and runs on iOS 13.4 and later, which reaches far older iPhones than anything else here.

Not the pick for sauna, or anything on the wrist.

Brisk: challenges and somewhere to plunge

Brisk logs cold plunges with their duration and temperature, sets challenges that earn accolades, and has a map of spas, gyms and hotels where you can plunge away from home. A dashboard shows sleep and heart rate alongside your sessions.

Not the pick for sauna, or timing from the wrist.

Wim Hof Method: breathwork first

The Wim Hof app is built around guided breathing, courses and mindset, with cold exposure practice alongside, an Apple Watch app and a community. It has more ratings than the other eight put together. For breathing exercises nothing else on this list is a substitute, Contrast included.

Not the pick for a detailed record of plunge rounds and the water they happened in. Wim Hof Method and Contrast compared.

A limit every watch app here shares

Apple’s own guidance, published on 14 September 2026, advises against wearing any Apple Watch other than Ultra in a sauna, against wearing Ultra in a sauna above 55 °C (130 °F), and against wearing any model in a steam room. A traditional sauna runs far hotter than 55 °C.

So for most saunas, heart rate from the wrist is off the table whichever app records it, and the useful thing an app can do is time the round with the watch left outside. Hot baths and cold plunges are not on Apple’s list. Can you wear an Apple Watch in a sauna? goes through what that means in practice.

Four things the listings rarely say

Whether the temperature is measured or typed. Most apps that store a water temperature have a field for you to fill in from a floating thermometer. Ultra Plunge and Contrast read the watch’s sensor instead, which Apple exposes to apps along with a submersion state, and the Plunge app reads its own tub. Where these listings use the word “automatic”, it refers to saving to Apple Health or sharing to Strava.

What the session becomes in Apple Health. Apple has no sauna or cold immersion workout type, so every app picks the nearest one. Contrast saves a Cooldown workout with heart rate and water temperature. Only three listings here mention Apple Health at all.

Whether it estimates calories for heat. Ultra Plunge advertises calorie and sweat-loss estimates. Contrast shows none, because heat raises heart rate without a matching rise in energy use, so a calorie figure built on heart rate overstates what a sauna burns. Does a sauna burn calories? has the detail.

Whether a computed number shows its method. Anything past a timer is a computation. Contrast documents its fourteen metrics with the method, the limits and an evidence label, and two of them say outright that the measure is the app’s own and untested. For someone who wants a timer and a history, that is a lot of reading attached to a simple need.

What Contrast does not do

It controls no tub, offers no guided breathing or protocols, and has no community, challenges or streaks. It runs on iPhone and Apple Watch only, needs iOS 17 or later, and will never support Garmin or Android, because the water sensor and HealthKit are Apple’s. It records the time and an air temperature you type in for a sauna round and nothing more about the room, and it covers heat, cold and rest rather than red light or hyperbaric oxygen. Each of those is a good reason to choose one of the other eight.