Human body temperature is a vital sign that indicates the state of your health. Recent studies, including one that monitored 96 adults over a two-week period, have shown that average body temperatures can range from 35.2C (95.4F) to 37.4C (99.3F). This suggests that knowing your own average temperature when healthy can be more informative than relying on a standardized ideal. Thousands of simultaneous chemical reactions in the body require a stable temperature, and our bodies struggle with severe temperature fluctuations, which can lead to permanent organ damage or death in extreme cases of hypothermia or hyperthermia.

The decline in average body temperature in the United States may be due to a decrease in metabolic rate, possibly linked to a reduction in inflammation levels. Feeling unusually cold can be due to various factors such as low body weight, which affects your body’s insulation and heat generation, or skipping meals. It’s important to understand that body temperature can vary based on where and how it’s measured, and using a low-reading thermometer may be necessary.

For older adults, maintaining body temperature is crucial, as they are at higher risk for hypothermia, even in mild cold conditions. Body temperature naturally varies throughout the day, often peaking in the afternoon. Fever in adults is defined as a body temperature of 100.4 F (38C) or higher, with various levels of severity. Recognizing and responding to the signs of body temperature changes can help maintain good health.

For more detailed information on body temperature and health, visit Harvard Health, Harvard Health Blog, Stanford Medicine, Harvard Health, University of Rochester Medical Center, Center for Healthy Aging, and Harvard Health.