Recent research indicates a shift in the average human body temperature, prompting a reevaluation of what is considered normal. Historically, the “normal” body temperature was established at 37 degrees Celsius (98.6 degrees Fahrenheit). However, modern studies, including a Stanford research conducted in 2020, suggest that this benchmark may be outdated. The average body temperature in the United States has shown a gradual decrease since the 1800s.

A comprehensive analysis of 20 studies, conducted between 1935 and 1999, found the average oral temperature to be around 97.5°F. Further research in 2023, along with an earlier study involving more than 35,000 individuals, identified the average body temperature closer to 97.9°F. This decline over the years indicates that the traditional 98.6°F may no longer be the norm.

Hypothermia, a critical medical condition, is defined as a body temperature dropping below 95°F (35°C). It’s essential to recognize that hypothermia can occur in various settings, not only in extreme cold but also in cool temperatures, especially if an individual is wet from rain or sweat, or immersed in cold water.

The normal body temperature varies based on several factors, including gender, physical activity, food and fluid intake, time of day, and, in women, the menstrual cycle stage. For a healthy adult, normal body temperature can range from 97.8°F (36.5°C) to 99°F (37.2°C).

Body temperature typically peaks in the afternoon and is lowest in the morning. Fever is characterized by a body temperature exceeding 100.4°F (38°C). Fevers are categorized based on severity, with a low-grade fever ranging from 99.1 to 100.4°F (37.3 to 38.0°C).

This shifting understanding of body temperature norms highlights the importance of knowing one’s average temperature when feeling well, rather than relying solely on universal benchmarks. With Harvard Health and University of Rochester Medical Center contributions, we see an evolving perspective on what constitutes a normal body temperature.