How close must a stationary source be to a weather station in order for that station’s data to be applicable to the stationary source?
EPA has not set specific distance limits but will allow owners and operators to use their best judgment to determine if the data from a weather station should reasonably apply to the stationary source. Factors such as topography and distance between the stationary source and a weather station should be taken into consideration when evaluating the applicability of the weather station’s data to the stationary source.
Source: https://www.epa.gov/rmp/using-meteorological-station-data-site-consequence-analyses