A new version of the Community Multiscale Air Quality (CMAQ) model, version 5.2 (CMAQv5.2), is currently being developed, with a planned release date in 2017. The new model includes numerous updates from the previous version of the model (CMAQv5.1). Specific updates include a new windblown dust scheme; updates to the organic aerosol treatment; updates to the atmospheric chemistry, including the Carbon-Bond 6 chemical mechanism; and various updates to the cloud treatment in the model. In addition, a new lightning assimilation scheme has been implemented in WRF, the meteorological driver for the CMAQ simulations, which greatly improves the placement and intensity of precipitation, which in turn results in improved CMAQ performance. Comparisons between CMAQv5.1 and v5.2 show that ozone (O-3) mixing ratios generally increase in the summer with CMAQv5.2, which results in increased bias, while fine particulate matter (PM2.5) concentrations also increase in the summer, which results in decreased bias.