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CoCoRaHS - The Community Collaborative Rain, Hail, and Snow Network



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Become a Weather Observer for Your Community!


What is CoCoRaHS?

CoCoRaHS (the Community Collaborative Rain, Hail, and Snow network) is a grassroots volunteer network made up of people of all ages and backgrounds who measure precipitation including rain, hail, and snow. Using low cost measuring tools, volunteers figure out how much precipitation fell at their location each day, then they using the CoCoRaHS website to report their observations. CoCoRaHS originated with the Colorado Climate Center at Colorado State University in 1998 thanks in part to the Fort Collins flood a year prior. In the years since, CoCoRaHS now includes thousands of volunteers nationwide. The National Oceanic and Atmospheric Administration (NOAA) and the National Science Foundation (NSF) are major sponsors of CoCoRaHS.

Who can participate?


  • Weather enthusiasts
  • Farmers/gardners/naturalists
  • Teachers/students - CoCoRaHS can be a fun and effective learning tool!
  • Lake/reservoir managers
  • Construction workers and other outdoor occupations that are impacted by precipitation
  • Everyone! Anyone who is willing to check their rain gauge each day


How do I get started?


  • 1. Sign up at to provide your location and contact information.
  • 2. Obtain a plastic 4" rain gauge. Information on where to get one can be found at
  • 3. View the online training materials (see the training section below)
  • 4. Setup your gauge in a good location. Click here for tips on where to install your gauge.
  • 5. Begin measuring precipitation and send in your reports each day.


Why is CoCoRaHS important? How will my observations be used?

Rainfall amounts can vary tremendously over a short distance - by inches over a distance of just a few city blocks! While there are some rain gauges across the area providing data to us and weather radar can estimate how much rain has fallen in a particular spot, the best way for us to know how much rain has fallen is for several people to take actual rain gauge measurements. This data is important and is used in several ways. Some examples include...


  • River forecasting: Rain/snowfall data helps us forecast levels along area rivers, creeks, and lakes. CoCoRaHS data is used directly in these forecasts.
  • Flood warnings and forecasts: Rainfall data aids in the warning process by giving us an idea of how saturated the soil is and how much rain it would take to cause flooding in a particular area
  • Verification: Rain/snowfall data gives us an idea of how accurately our radar is estimating precipitation amounts. 99% of our snowfall data comes from volunteer observers and storm spotters.
  • Drought: Rainfall data over an extended period of time can help pinpoint areas being most affected by drought
  • Research: Rain/snowfall data can be used by scientists to better understand the way the atmosphere works, which can lead to better forecasts and warnings
  • Other users: Farmers, gardeners, pest control, airports, emergency managers, city utilities, insurance adjusters, engineers, outdoor & recreation interests, teachers, students, and many more!


You can always view the latest CoCoRaHS data from our forecast area each morning on our daily CoCoRaHS product and some of the reports are displayed on our daily precipitation maps.


Training Material