Can certain weather conditions reduce the spread of COVID-19?

Posted at 7:23 PM, Mar 19, 2020
and last updated 2020-03-19 19:23:44-04

WARM, humid weather can reduce the spread of COVID-19 — Here in Southwest Florida, we live in a warm and humid climate. Studies have shown that peak season for the common cold and influenza in the United States is winter and early spring. This is due to weather conditions being more warm and humid late spring and into the summer months. Researchers have been curious to see if the same will be true for COVID-19.

A new study examines the effect of weather on the spread of the SARS-Cov-2 virus, which causes the COVID-19 illness. This study looks at how temperature and humidity may affect the transmission of COVID-19, the illness caused by the new coronavirus. Researchers have analyzed data and found that an increase of just one degree Celsius and 1% relative humidity increase substantially lower the virus’s transmission. This means that high temperature and high relative humidity significantly reduce the transmission of COVID-19.

The researchers studied 100 different Chinese cities that each had more than 40 cases of COVID-19 in a 3 day period during the end of January, before China intervened to stop the spread of the virus. Researchers were able to observe the natural spread of the virus before public health measures and accounted for GDP per capita, which normalized the differences in health care facilities, and the normalizations for population density.

The study showed that the direct impacts of air temperatures and humidity levels could be seen plainly in the severity of outbreaks during the earlier stages of the virus spread. In fact countries with relatively lower air temperature and lower humidity saw severe outbreaks than warmer and more humid countries. Research shows that the severity is negatively related to temperature and relative humidity using 14 countries with more than 20 new cases during a period from February 8 to February 29.

In regards to China the study also found that northern cities, where temperatures and relative humidity were lower, had larger transmission values compared to cities along the country's southeast coast. Scientists' findings align with what some experts have suspected about weather's impact: In cold environments there is a longer virus survival than in warm environments.

Another interesting fact is that UV light has been proven to kill other strains from the coronavirus family, like SARS and MERS. As spring and summer approach in the Northern Hemisphere some experts are also pointing to the increased amount of UV rays from the sun which could be a factor in slowing down the virus.

In regards to findings related to forecast temperatures and humidity, research concluded that the arrival of summer and rainy seasons in the Northern Hemisphere can effectively reduce the transmission of COVID-19, while the risk for the continued spread of the illness will remain in some countries in the Southern Hemisphere.

The good news is that at least the weather is not working against us for the news few months. Researchers even added that normal summer temperatures and relative humidity in Tokyo suggest that the transmission would be significantly reduced in time for the 2020 Summer Olympics, currently scheduled to be kick off on July 24.