Fire managers must consider air-quality impacts when planning prescribed burns or devising wildfire containment strategies. Particulate matter (PM) is the primary pollutant of concern: it is the major component of smoke and has known detrimental influences on human health and the environment. The present study examines wildfire–weather–PM interactions and the resulting impacts on urban air quality and visibility in Tucson, Arizona, USA. Few violations of air-quality standards were recorded during large wildfire events in the study area. When examined at a higher-resolution time scale, the impacts of the fires on urban air quality are apparent. The present study also found that extreme PM values were linked to humid and windy conditions, wildfires appear to have a greater impact on PM₁₀ concentrations than PM_2.5 concentrations, and PM₁₀ is more closely tied to visibility degradation during fire events than PM_2.5. Comparison of actual PM concentrations to those predicted by a regulatory model indicates that the model overestimates standard exceedances, with resulting implications for prescribed burn planning.