All datasets with NetCDF format end with a ``.nc'' suffix. If these datasets contain time averaged data, the time at which the data is defined is at the middle of the averaging period (not at the end). For example, a monthly mean windstress for September would be defined at Sept 15th. This is done to prevent confusion on plots. Otherwise, if the convention of placing the time stamp at the end of the averaging period were followed, the same plot would show a date of October 1st at zero hours.