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  Citizens Weather Observer Program (CWOP) Data

Citizen Weather Observer Program (CWOP) Data



The Citizen Weather Observer Program's (CWOP) data is quality controlled through MADIS. The program is made up of ham radio operators and other private citizens around the world that have volunteered the use of their weather data for education, research and use by interested parties.

CWOP is a public-private partnership with three goals:
  1. To collect weather data contributed by citizens.
  2. To make these data available for weather services and homeland security.
  3. To provide feedback to the data contributors so they have the tools to check and improve their data quality.
CWOP has been sending data to MADIS since MADIS started on July 1, 2001.

Interested in signing up for a new Citizen or HAM Radio Operator account to send weather and/or snow data to MADIS? See below.
  • To send weather data, please click here. You can also update an existing CWOP account here as well.
  • To learn more about how to send/enter snow data and/or to sign up for a new snow account, please click here.

Geographic Coverage


Data Schedule

Data arrive every 5 minutes. The current and previous hour's data are processed every 5 minutes. Data are stored based on thier observational time stamp in netcdf files that contain observations from the top of the hour until 59 minutes into the hour (e.g., the 0000 file covers 0000 - 0059).

Data that arrive after 2 hours following the time of the observation are processed in a "data recovery" mode, where once a day batch processing is performed to reprocess data that are 35 day's, 7 day's old, and 1 day old. These data are available with all communications methods supported by MADIS except for ldm.


Typical daily volume for all MADIS datasets can be seen here.


No restrictions. All observations are publicly accessible.

Variable Details

Last updated 02 December 2021