National Weather Service United States Department of Commerce

Community Collaborative Rain, Hail, and Snow Network

You can let the National Weather Service know how much rain, hail, or snow you've measured in your back yard! The Community Collaborative Rain, Hail, and Snow (CoCoRaHS) Network is in place across both Alabama and Tennessee. CoCoRaHS is a unique, non-profit, community-based network of volunteers of all ages and backgrounds working together to measure and map precipitation (rain, hail and snow). The program will help meteorologists, hydrologists, and researchers study the variability of precipitation across the Tennessee Valley, and the accumulated data will be available to anyone with a use or interest in precipitation data.

Eight Inch Rain Gage


How did CoCoRaHS get started?

CoCoRaHS started because of a devastating flood that struck Fort Collins, Colorado in 1998. When researchers went back to examine the precipitation data, they discovered that the rainfall leading to the flood missed all of the official gages. Colorado State Climatologist Nolan Doeskin developed a new volunteer observing network to fill in the gaps between official gages called CoCoRaHS.

Sounds great! How can I sign up?

There are three options available, depending on where you live and the measuring equipment you have.

  1. To find out more, visit the CoCoRaHS web site at If you'd like to sign up, just visit the web site and click on "Join CoCoRaHS" to register your backyard or schoolyard as a reporting site. Once you register and begin to report, your observations will become part of the record and will be plotted on maps of your county and state. You can view the maps and see how your observation fits in with your neighbors.
    If you decide to sign up, we encourage you to go through the online training located on the CoCoRaHS web site. It will detail proper gage siting techniques as well as other program information. Note that you will need to provide your own rain gage (you can purchase one through CoCoRaHS, and more details can be found on the CoCoRaHS site).
  2. If you live in Madison or Limestone Counties, there is a local metro-area precipitation network called CHARM (Cooperative Huntsville Area Rainfall Measurements) operated by NASA. Signing up for and reporting to CHARM will feed your data to both CHARM and to CoCoRaHS! Click here to find out more about CHARM and its interaction with CoCoRaHS.
  3. If you would like to participate but also have a thermometer available, we encourage you to sign up to become an NWS Huntsville Backyard Observer! More information on this program is available here.

Note: If you are already reporting your data to NWS Huntsville as a backyard or cooperative observer, or if you are a member of the CHARM (Cooperative Huntsville Area Rainfall Measurements) network, your data is already being received. You are still welcome to join CoCoRaHS if you wish to to view your data on the CoCoRaHS webpage though.

How can I find out more?

If you'd like to know more about local CoCoRaHS efforts, feel free to contact the National Weather Service office in Huntsville, call the office at 256-890-8503.

To find out more about CoCoRaHS, visit the website at

For more information about the CHARM network, visit their website at