Warm Weather Will Slow Down COVID-19, But Only Slightly

CAMBRIDGE, Mass. — Millions of people have been hoping that COVID-19 will disappear, or at least become much less prevalent, as temperatures increase with the onset of spring and summer. Unfortunately, a new study from Mount Auburn Hospital has found that past 52 degrees Fahrenheit, warm weather doesn’t seem to influence the coronavirus much at all.

So, while warm weather will slow down the virus slightly, it certainly won’t be enough to stop it completely.

The study’s authors examined the influence of temperature, precipitation, and UV index on U.S. COVID-19 case rates over the first spring months of 2020. They found that the number of COVID-19 infections did seem to somewhat decrease with warming temperatures up to 52 degrees Fahrenheit. Past that temperature, warm weather doesn’t appear to effect the virus. Similarly, higher UV indexes do slow the rate of new infections, but only to a small degree. Precipitation, meanwhile, doesn’t have any impact at all.

Daily coronavirus cases from all over the United States between January 22nd and April 3rd were included in this research. The work was made possible via John Hopkins University’s COVID-19 Dashboard and weather data provided by the National Centers for Environmental Information.

“While the rate of virus transmission may slow down as the maximum daily temperature rises to around 50 degrees, the effects of temperature rise beyond that don’t seem to be significant,” says first author Dr. Shiv T. Sehra, director of the Internal Medicine Residency Program at Mount Auburn Hospital and Assistant Professor of Medicine at Harvard Medical School, in a release. “Based on our analysis, the modest association suggests that it is unlikely that disease transmission will slow dramatically in the summer months from the increase in temperature alone.”

Researchers also modeled the spread of COVID-19 in a given area depending on steady temperatures (between 20-30 degrees Fahrenheit, 40-50 degrees, and so on). They noted that fewer cases would pop up in an area where temperatures were above 50 degrees five days earlier, while the largest increase in infections would occur in an area with a temperature below 30 degrees that day. So, temperature is still influencing infection rates to some degree.


The CDC has already said that COVID-19 may become much worse in the coming fall and winter.

“Our results are in line with those predictions,” Sehra notes. “We also caution that the disease may get worse in the fall and winter months.”

“To the best of our knowledge, this is probably one of the first peer-reviewed studies that examine the influence that temperature, precipitation and UV light have in terms of virus transmission in the general population across the United States,” she adds.

Still, the study’s authors admit their work had some limitations. Climate data for some state capitals were applied to entire states, and none of the data collected featured temperatures above 70 degrees. So, this study really can’t say what effect warmer temperatures over 70-75 degrees may have on infection rates.

The study is published in Clinical Infectious Diseases.

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