Skin Temperature

• Good-to-know
• What is Skin Temperature?
• How NOWATCH measures Skin Temperature
• How to read the Skin Temperature chart 
• What’s the value of Skin Temperature insights

Good-to-know

• Skin Temperature is available in the Overview screen.

What is Skin Temperature?

Skin Temperature is the temperature measured at the surface of your skin, typically during sleep, when external influences like movement and environment are minimal. It is not the same as your core (internal) body temperature.

NOWATCH tracks Skin Temperature to help you understand relative changes over time, rather than focusing on a single absolute value.

How NOWATCH measures Skin Temperature

Skin Temperature is measured during sleep and interpreted in relation to your personal baseline.

Key points to know:

• Measurements are compared against your own baseline

• Insights focus on deviations from your normal pattern, not exact temperature values

• Because everyone’s baseline is different, Skin Temperature insights are fully personalized

Skin Temperature vs. Body Temperature

It’s important to understand the difference:

• NOWATCH measures Skin Temperature, not internal body temperature

• Skin and core body temperature behave differently

• In some cases, a higher internal body temperature can correspond with a lower Skin Temperature, due to how the body regulates heat

For this reason, patterns and trends over time are more meaningful than individual readings.

Relative changes, not absolute values

Skin Temperature is most useful when viewed as a trend.

Instead of asking “What is my temperature?”, the more helpful question is:

“How much has my Skin Temperature changed compared to my usual baseline?”

• Small day-to-day fluctuations are normal

• What matters is consistent deviation across consecutive days

How to read the Skin Temperature chart 

Typical range (yellow zone)

This zone represents what is normal for you. It remains relatively stable and helps highlight meaningful deviations.

Skin Temperature during sleep per night (yellow bars)

The bars show your average Skin Temperature during each night of sleep. Minor nightly changes are expected.

Skin Temperature may rise due to:

• Sleeping in a warm room

• Alcohol consumption

• Late or intense exercise

If elevated values persist for more than two consecutive days, it may indicate that your body is under strain or fighting something off.

Skin Temperature can also vary during certain phases of your cycle.

Baseline (yellow line)

Your baseline reflects your typical Skin Temperature.

Wear requirement

You need at least 7 nights of sleep data to view your baseline. It gradually adapts over time (around 60 days) as your physiology changes. 

7 nights of sleep data means that the app must have detected sleep, and/or that sleep was logged manually, for seven consecutive nights.

What’s the value of Skin Temperature insights

Skin Temperature is a contextual signal, not a diagnostic tool. It works best when viewed alongside other metrics.

You can use it to:

• Spot early signs of illness or recovery needs
  Consecutive days above or below your baseline may signal illness, stress, or physiological strain.

• Understand lifestyle impacts
  Compare Skin Temperature with stress, sleep, and HRV to see how habits affect your body.

• Support smarter rest and activity decisions
  Sustained deviations (around two days or more) can be a cue to slow down, rest, or check in with how you feel.

If you notice ongoing changes from your baseline and don’t feel well, it’s best to listen to your body and consult a healthcare professional.