The I/O API-netCDF files in this archive contain estimates of monthly 12-km resolution cloud-to-ground (CG) flash counts over North America for 2002-2014 on the standard 12-km United States CMAQ grid. These data were created using National Lightning Detection Network (NLDN) raw flash data from Vaisala. The flash rate data sets for 2002-2013 are unchanged from the January 2015 Version. However, the method used to type a flash as CG or intra-cloud (IC) in the 2014 data set differs from what was used for 2002-2013 (see accompanying README file for details on how the data sets were prepared). These data can be used to simulate lightning NOx emissions in CMAQv5.0 and higher.