If you’ve been exposed to coronavirus—or if you’re just worried about getting sick—you’re probably checking your temperature pretty regularly these days. And that’s what you should be doing, given that having a fever is the most commonly reported symptom of COVID-19. But your temperature fluctuates throughout the day, which means that knowing when you should take your temperature can be just as important as the number on your thermometer. If you’re monitoring yourself for a fever, there’s a specific time of day when you’ll get the most accurate results.
Speaking to The New York Times, William Schaffner, MD, a professor of preventive medicine and infectious diseases at Vanderbilt University, said that you should take your temperature in the evening, between the hours of 4 p.m. and 9 p.m. That’s because people tend to run cooler earlier in the day; evening is when your temperature peaks, so if you’re worried about having a fever, that’s when it would be most likely to show up on a thermometer.
To be clear, evening isn’t the only time you should be taking your temperature, especially if you know that you’ve been exposed to someone with coronavirus. For people who have come into contact with COVID-19, the Centers for Disease Control and Prevention (CDC) recommends that you self-monitor for all coronavirus symptoms, including fever. That means checking your temperature twice a day. Per Schaffner’s advice, it’s essential that one of those checks be done in the evening.
As for what temperature to look out for when you’re checking for a fever, The New York Times says that a reading of 100.5 degrees Fahrenheit or above is cause for concern. (The CDC considers a fever to be a temperature of 100.4 degrees or higher.) It’s also important to know that some people naturally have higher or lower body temperatures than others. While 98.6 degrees Fahrenheit was once considered the average, a January study in eLife revealed that the current average temperature is closer to 97.9 degrees.
The variance from person to person is all the more reason to keep a watchful eye on the thermometer and follow the CDC’s recommendation of twice-daily checks. Just make sure one of those checks falls within the window when your temperature will be at its highest. And if you are running hot, These Are the Worst Things You Can Do if You Have a Fever.