National Weather Service United States Department of Commerce

An Active Start to the Week

A slow moving and large-scale system will produce widespread rain and thunderstorms the next few days across the central and southern Plains into the Mid to Lower Mississippi Valley. Severe storms will be common across Texas through Tuesday before spreading eastward. The locally heavy rain will produce possible flooding and have a similar transition to the east through midweek. Read More >


General Access To Data and Products



This is an open service for general use

DO NOT access these servers with programs/scripts that are:
  1. too repetitive a login over time ( know frequency data changes ), opening up multiple sessions to access the same data products

ACCESS Controls that are established for this service are:

  1. No more than 20 concurrent sessions are allowed per customer, 30 min duration limit per download (don't use slow connections), Session will drop after 5 minutes idle to permit others to access.
  2. No persistent session in excess of 45 minutes (txt), 3 hours (bin)

The majority of our human readable warnings, forecasts and observations are downloadable for screen viewing using standard web browsers. The information is provided on three major data providing services. The NWS home page at provides access to icon and graphical rendered forms of original NWS warnings and forecast products from every forecast office. This site is the main portal for linking to other web sites within the NWS. By virtue of you viewing this page, you are on the home page web site and have access to a large amount of NWS documentation on NWS services, practices, meteorological procesedures, and standards of operations.

Another major service is - named the Internet Weather Source and abbreviated as IWS. This service provides tailored composite forecast products by specific forecast area or county warning area and also provides METAR site observations in a decoded form by full site name. This site has links to facsimile charts for viewing on the PC browser.

The third server URL is iwin.nws.noaa.govwhich operates the Interactive Weather Information Network, abbreviated as IWIN. This service provides the original warnings and forecasts as generated by the forecast office. No attempt is made to separate the issued product by forecasted geographical/zone area.

All three of these services contain only current products and observations. They do not store archived data and products. The site pages also link to other servers that maintain extensive product data sets and observational data files for FTP access.

A new addition to the NWS web service is the NEXRAD composite images for browser viewing. These products are also available from web server located at NWS forecast office across the United States. Each NWS Regional Headquarters operates Web sites that hold the product images of their regional area NEXRAD sites.

There is a "help guide" that can aid you in establishing the procedures you should use for retrieving data and forecast products from our file servers using the FTP protocol. This help guide addresses both the standard directory and file name practices used by the Gateway servers listed below and the parsed "individual data and forecast products" processed for our own use.

The structure of the data and products on the server is a flat ASCII file for extraction by scientific meteorological research groups and others interested in these data sets. The various files contain collections of hydrometeorological forecast products or observational data generated in WMO message format; as well as, other files which contain major computer model data fields NOT generated in WMO message format. Files are created at specific time intervals and all data available in the telecommunications switching system at file creation time are included in each file.

About the Server Directory Structure and File Content Structure

Please review our Directory & File Name Standards pages for details and how file contents are structured to help in reading the contents and be able to parse out the messages through automated means.

All file contents (except for some model data set files) are collective groups of WMO messages. All meteorological data are coded in WMO standard code forms which are documented by WMO Manual 306. The model data set files having contents with no WMO abbreviated headings are all in GRIB or BUFR code format.