Background: The current
coronavirus disease 2019 (COVID-19) is spreading globally at an accelerated rate. There is some previous evidence that weather may influence the incidence of
COVID-19 infection. We assessed the role of meteorological factors including temperature (T) and relative humidity (RH) considering the concentrations of two
air pollutants, inhalable coarse particles (PM10) and
nitrogen dioxide (NO2) in the incidence of
COVID-19 infections in Finland, located in arctic-subarctic climatic zone. Methods: We retrieved daily counts of
COVID-19 in Finland from Jan 1 to May 31, 2020, nationwide and separately for all 21 hospital districts across the country. The meteorological and air quality data were from the monitoring stations nearest to the central district hospital. A quasi-Poisson generalized additional model (GAM) was fitted to estimate the associations between district-specific meteorological factors and the daily counts of
COVID-19 during the study period. Sensitivity analyses were conducted to test the robustness of the results. Results: The incidence rate of
COVID-19 gradually increased until a peak around April 6 and then decreased. There were no associations between daily temperature and incidence rate of
COVID-19. Daily average RH was negatively associated with daily incidence rate of
COVID-19 in two hospital districts located inland. No such association was found nationwide. Conclusions: Weather conditions, such as air temperature and relative humidity, were not related to the
COVID-19 incidence during the first wave in the arctic and subarctic winter and spring. The inference is based on a relatively small number of cases and a restricted time period.