People could be at greater risk of contracting COVID-19 in winter, according to research that's linked lower humidity to the spread of the virus.

The coronavirus could become a seasonal disease, with people at greater risk of contracting it during winter, after research showed lower humidity could lead to a significant increase in the number of cases.

A study conducted in NSW during the early epidemic stage of COVID-19 found an association between lower humidity and an increase in locally acquired positive cases.

Researchers at the University of Sydney and its partner institution Fudan University in Shanghai, China, discovered a one per cent decrease in humidity could increase the number of COVID-19 cases by six per cent.

"COVID-19 is likely to be a seasonal disease that recurs in periods of lower humidity. We need to be thinking if it's winter time, it could be COVID-19 time," epidemiologist and lead researcher Professor Michael Ward said on Tuesday.

However, he says the study was limited to cases contracted in the summer months, mostly in and around Sydney, so further research is needed to determine how humidity impacts COVID-19 and the extent to which it drives case notification rates.

Previous research has identified a link between climate and occurrence of SARS-CoV cases in Hong Kong and China, and MERS-CoV cases in Saudi Arabia, and a recent study on the COVID-19 outbreak in China found an association between transmission and daily temperature and relative humidity, the team said in a statement.

"The pandemic in China, Europe and North America happened in winter so we were interested to see if the association between COVID-19 cases and climate was different in Australia in late summer and early autumn," Professor Ward said.

"When it comes to climate, we found that lower humidity is the main driver here, rather than colder temperatures. It means we may see an increased risk in winter here, when we have a drop in humidity.

"But in the northern hemisphere, in areas with lower humidity or during periods when humidity drops, there might be a risk even during the summer months. So vigilance must be maintained."

The study is published in Transboundary and Emerging Diseases and is the first peer-reviewed study of a relationship between climate and COVID-19 in the southern hemisphere.