CHARM Frequently Asked Questions

What is CHARM?
The Cooperative Huntsville Area Rainfall Measurements (CHARM) network is comprised of volunteers who take daily rainfall measurements in the morning. The composition of volunteers ranges from middle school students to PhD scientists. The network also incorporates automated National Weather Service and United States Geological Survey raingauges.

How are the CHARM measurements going to be used?
Several scientists at the Global Hydrology and Climate Center (GHCC) have expressed a need for this type of data to validate weather radar data, and variations in soil moisture and latent heat fluxes (kind of like evaporation of water from the surface) as estimated from satellite and other remotely sensed data. The database will also help disaster investigations like the Aldridge Creek flood of two years ago, and other flooding situations. It has already been used to support a NASA environmental study for MSFC and Redstone Arsenal. It also serves as an educational and community outreach activity to involve the community in NASA related activities and show them the benefit of NASA research.

If it doesn't rain do I have to enter a rainfall value (of 0.00)?
No, the database will show "no report." However, it is better to enter "0.00," because this helps validate information. To make it easier on all of us, our resident CHARM website guru has allowed multiple entries of "0.00" for consecutive days. Just type range of days with no rain and "0.00" and the software will do the rest.

It rained while I was out of town. How do I enter my report?
Select the appropriate days that you were gone and report the amount of rain in your gage. The software will automatically fill in "missing" for all days except for the final day when you reported the rain amount.

Is this a short term thing?
We plan to make CHARM measurements indefinitely. If you are using a NASA gauge and cannot make measurements anymore, just return your gauge and we will issue it to someone else, no questions asked.

I don't own a gauge or need a new one. Can you recommend one?
We recommend the official CoCoRaHS gauges, which you can purchase from

I woke up this morning and found water from fog or dew in my gauge. Do I report it?
Only report precipitation in the form of rainfall or snowfall. Although you’re welcome to note dew or fog deposition in your notes, please do not report it as precipitation.


Technical Contact and Page Curator: Kevin M. McGrath (
Responsible Official: Dr. Gary J. Jedlovec (

Last Updated: January 9, 2011