Effect of Temperature, humidity, and wind speed on COVID-19

Effect of  Temperature, humidity, and wind speed on COVID-19. Jefferson T, Heneghan C.


Published on June 18, 2020

Reference Islam N, Shabnam S, Erzurumluoglu AM. Temperature, humidity, and wind speed are associated with lower Covid-19 incidence. medRxiv. 2020:2020.03.27.20045658. medRxiv. 2020:2020.03.27.20045658. 2020
Study type
Country 310 regions from 116 countries by 12 March 2020
Setting Public
Funding Details Public
Transmission mode Meteorological
Exposures Atmospheric

Bottom Line

Calm, cold, dry and overcast conditions are favourable to the transmission of COVID-19.

Evidence Summary

The authors identified an inverse relationship between temperature (in blocks of 5 degrees Centigrade changes) and humidity (in 10% steps) and the incidence of Covid-19 even before symptoms appear. 

This relationship suggests that a cold and dry environment is a more favourable condition for virus survival and incubation, similarly to what has been observed with SARS-CoV and MERS-CoV.2. They also found an inverse association with wind speed which may indicate a shorter suspending time in the air of Covid-19 and an inverse association with a higher UV index (but only in the two weeks prior to the incidence), which is in keeping with viral destruction at higher temperatures.

What did they do?

The authors assessed the association between concurrent and historical meteorological factors (temperature, relative humidity, wind speed, and ultraviolet -UV- index) and the incidence of Covid-19 in 310 regions from 116 countries with reported cases of Covid-19 by March 12, 2020.
By historical factors, the authors mean preceding 1-2 weeks to allow for the incubation period. Calculations were adjusted for the concentration of ozone as an indicator of pollution.

 Data at 

Study reliability

The report is four pages long and maybe a preprint advanced copy of a larger study. The authors do report the ideal ranges of meteorological variables for transmission only the changes, nor do they explain the starting point of the lag time (e.g. index case), just using the term “incidence”.

Clearly defined setting Demographic characteristics described Follow-up length was sufficient Transmission outcomes assessed Main biases are taken into consideration
No No Yes Yes Yes

What else should I consider?

Studies with longer follow- up that vary across the seasons will increase our understanding of the play of the variables.

About the authors

Carl Heneghan

Carl is Professor of EBM & Director of CEBM at the University of Oxford. He is also a GP and tweets @carlheneghan. He has an active interest in discovering the truth behind health research findings

Elizabeth Spencer

Dr Elizabeth Spencer; MMedSci, PhD. Epidemiologist, Nuffield Department for Primary Care Health Sciences, University of Oxford.

Tom Jefferson

Tom Jefferson, epidemiologist.