The National Oceanic and Atmospheric Administration (NOAA), in partnership with the Environmental Protection Agency (EPA), have developed an operational Air Quality Forecasting System for the contiguous United States. The system, which couples NOAA's WRF (Weather Research Forecast) meteorological model with EPA's Community Multiscale Air Quality (CMAQ) model, provides public forecasts of hourly, peak 1- and 8-hour ozone (O3) concentrations throughout the summer of 2007. In order to characterize the performance of the modeling system a suite of statistical metrics that facilitates evaluation of both discrete-type forecasts (observed versus modeled concentrations of O3) and categorical-type forecasts (observed versus modeled exceedances of both the maximum 1-hr and 8-hr standards for O3) will be applied over various temporal and spatial resolutions. Ozone data from more than 1000 monitors obtained from EPA's AIRNOW monitoring network will be used in the evaluation.