Understanding Body Temperature Patterns
Body temperature is not static — it follows a natural circadian rhythm, being lowest in the early morning and highest in the late afternoon or evening. A daily variation of 0.4–0.8°C is completely normal. Tracking readings over several days allows you to distinguish a one-time spike from a persistent abnormal pattern.
Persistent low-grade fever (above 37.5°C) can be an early signal of infection, autoimmune disease, or hormonal imbalance. Consistently low temperatures may indicate thyroid dysfunction or nutritional deficiency. Multi-day tracking provides far more meaningful data than a single measurement.
Frequently Asked Questions
The most consistent readings come from measuring immediately after waking (before eating or drinking) and again before bed. Avoid intense exercise, hot beverages, or smoking for at least 30 minutes before measuring.
Yes. Rectal temperature is the most accurate, running about 0.5°C higher than underarm (axillary). Oral temperature falls between the two. This tool uses underarm measurements as the baseline.
Yes. After ovulation (the luteal phase), basal body temperature rises by 0.2–0.5°C. Tracking basal body temperature consistently can help identify ovulation timing and menstrual cycle patterns.