Impacts of regional climate on the COVID-19 pandemic

The COVID-19 pandemic has led to six million confirmed cases by May 31, 2020. Impacts of regional weather and climate on epidemics have been investigated but need further study with new methods. We combined the number of monthly confirmed new cases and death with month, latitude, temperature, humidity, rainfall, and sunshine ultraviolet (UV) to explore the climate impact on epidemics in 116 countries and territories with at least 1000 confirmed cases. Correlation and regression analyses were performed with Stata. Humid subtropical climate regions had the most confirmed COVID-19 cases (24.4%). The case mortality in temperate marine regions was the highest (11.6%). Case-weighted means of the latitude, monthly maximum temperature, relative humidity, rainfall, and sunshine UV were 36.7 degrees, 20.5℃, 63%, 63mm, and 53.5, respectively. The case mortality was 7.44% in cold regions but only 4.68% in hot regions, 7.14% in rainy regions but only 3.86% in rainless regions, and 7.40% in cloudy regions but only 4.64% in sunny regions. Monthly confirmed cases increase as the temperature, rainfall, and sunshine UV rise in cold regions (r=0.34, 0.26, 0.26, respectively), but no correlation in hot regions. Every 1℃ increase in monthly maximum temperature leads to an increase in the natural logarithm of monthly confirmed new cases by 2.4% in cold regions. Monthly confirmed cases increase as the temperature, rainfall, and sunshine UV rise in arid regions (r=0.29, 0.28, 0.26, respectively), but no correlation in humid regions. Monthly confirmed new cases increase as the temperature and sunshine UV rise in rainy regions (r=0.30, 0.29), but no correlation in rainless regions. Monthly confirmed new deaths increase as the temperature and sunshine UV rise in cloudy regions (r=0.30, 0.30), but no correlation in sunny regions. It is wise to escape from an epicenter full of miasma to a hot sunny place in dry season without pollution. As peaking in the spring depends on the climate, the peak will go in the summer.