Several approaches have been used in the race against time to mitigate the spread and impact of COVID‐19. In this study, we investigated the role of temperature, relative humidity, and particulate matter in the spread of COVID‐19 cases within two densely populated cities of South Africa—Pretoria and Cape Town. The role of different levels of COVID‐19 restrictions in the air pollution levels, obtained from the Purple Air Network, of the two cities were also considered. Our results suggest that 26.73% and 43.66% reduction in PM2.5 levels were observed in Cape Town and Pretoria respectively for no lockdown (Level 0) to the strictest lockdown level (Level 5). Furthermore, our results showed a significant relationship between particulate matter and COVID‐19 in the two cities. Particulate matter was found to be a good predictor, based on the significance of causality test, of COVID‐19 cases in Pretoria with a lag of 7 days and more. This suggests that the effect of particulate matter on the number of cases can be felt after 7 days and beyond in Pretoria.