Skin Temperature
Celsius or Fahrenheit
Surface temperature at the wrist for the day, with a full time series. Deviations from personal baseline can precede illness or signal incomplete recovery.
How to read it
Read as deviation, not absolute temperature. Wrist skin runs cooler than core.
Key factors
- Ambient room temperature and clothing
- Menstrual cycle phase
- Fever or early-stage illness
What affects this metric
- Immune response after vaccination raises skin temperature for a day or two.
- A hot bath, shower, or sauna before bed raises it for hours.
- Illness and infection raise skin temperature above baseline.
- Alcohol raises skin temperature by dilating peripheral blood vessels.
- Room temperature, bedding, and clothing affect the reading.
- The menstrual cycle shifts baseline temperature across the month.
References
Peer-reviewed sources supporting the key factors, contributing factors, and typical optimal range shown above.
- Smarr BL, Aschbacher K, Fisher SM, et al.. Feasibility of continuous fever monitoring using wearable devices. Scientific Reports. 2020;10:21640. doi.org/10.1038/s41598-020-78355-6
- Presby DM, Capodilupo ER. Biometrics from a wearable device reveal temporary effects of COVID-19 vaccines on cardiovascular, respiratory, and sleep physiology. Journal of Applied Physiology. 2022;132(2):448–458. doi.org/10.1152/japplphysiol.00420.2021
- Baker FC, Driver HS. Circadian rhythms, sleep, and the menstrual cycle. Sleep Medicine. 2007;8(6):613–622. doi.org/10.1016/j.sleep.2006.09.011
- Okamoto-Mizuno K, Mizuno K. Effects of thermal environment on sleep and circadian rhythm. Journal of Physiological Anthropology. 2012;31:14. doi.org/10.1186/1880-6805-31-14
This guide is general information, not medical advice. Talk to your clinician about your own results.