Meteorological data collected by the National Weather Service and the U.S. military can readily obtained from several sources at little or no cost. This page lists some of these sources.

Where to get meteorological data for models.

WEBMET.COM contains a large amount of FREE surface and upper air meteorological data.

EPA Support Center for Regulatory Air Models (SCRAM) website contains several years of FREE surface meteorological data and mixing height data. These data have been included in the WEBMET.COM site given above.

National Climatic Data Center (NCDC) Online Store: Click on "I want quick access to your products" to order meteorological data on CD-ROM, or to download data.
To download more recent U.S. upper air data not yet available on CDROM, use the Radiosonde Database Access at These data are free.
There is a nominal fee for most data from NCDC.

"Procedures for Substituting Values for Missing NWS Meteorological Data for Use in Regulatory Air Quality Models" by Dennis Atkinson and Russell F. Lee, 1992. This document describes the EPA-recommended procedures for filling missing data for use in such air quality models as ISCST3 and AERMOD. It is identical to the text file "missdata.txt" available from the EPA SCRAM website, except that formatting has been applied to the text.

Note that for U.S. regulatory applications, use of data converted from a different format is generally not permitted. However, for other applications, the following format conversion software has been found to be useful:

NCDC_CNV is a program written by Russell Lee which can convert the abbreviated hourly surface meteorological data provided online by NCDC in comma-separated ASCII format, and the Integrated Surface Hourly Weather Observations (ISD, aka ISHWO, ISH, and ISHD) to the SAMSON format. The file is a zipped file containing the program, instructions, and a sample input file. This is being made available "as is" without charge by the developer, and may be freely distributed as long as the instruction file is included intact. This update was released 9/26/2008. However, as noted above, do not use this program to convert files for regulatory modeling in the U.S. The full ISD format can and should be used in the EPA regulatory models.