SKYWARN vs. CoCoRaHS: which spotter program is right for you?
SKYWARN trains volunteers to report severe weather in real time. CoCoRaHS measures daily precipitation. Here is how to choose — and why many spotters do both.
If you have ever wanted to help the National Weather Service, you have probably run into two acronyms: SKYWARN and CoCoRaHS. They sound similar, they are both free, and they both feed real data into NWS operations. But they answer very different questions.
The one-sentence version
SKYWARN trains you to report severe weather as it is happening — tornadoes, hail, damaging wind, flooding. CoCoRaHS trains you to measure daily precipitation with a standard rain gauge. Real-time danger vs. long-term climate record.
SKYWARN in detail
SKYWARN is run directly by your local NWS forecast office. Training is a single class — usually 90 minutes, often available online — that teaches you what a wall cloud actually looks like, how to estimate hail size, and how to report safely without becoming the story.
After class you get a spotter ID (or your name on a roster) and a phone number, email, or app to submit reports during warned storms. The commitment is opportunistic: you report when severe weather happens near you.
- Time commitment: ~90 minutes of training, then only during severe events.
- Best for: people who chase, farm, drive, or simply live somewhere with a view.
- Cost: free. No equipment required beyond a phone.
CoCoRaHS in detail
The Community Collaborative Rain, Hail and Snow Network is a citizen-science climate project run out of Colorado State University. Volunteers install a standardized 4-inch rain gauge and report the previous 24 hours of precipitation every morning at 7 a.m. local time.
That daily reading — even zero — becomes part of the official precipitation record used by NWS, USDA, drought monitors, and insurance adjusters. Hail reports and significant weather notes are also submitted through CoCoRaHS.
- Time commitment: ~2 minutes daily, ideally at 7 a.m.
- Best for: people at home in the morning, especially in rural areas.
- Cost: free training; the required 4-inch gauge runs about $35.
Which one should you pick?
If you can watch the sky during severe weather — you drive a lot, work outside, or live in Tornado or Dixie Alley — start with SKYWARN. If you have a stable home address and 2 minutes every morning, CoCoRaHS makes your yard a permanent climate station.
Many of the most useful volunteers do both. A SKYWARN spotter with a CoCoRaHS gauge can tell the NWS "1.75 inch hail and 2.14 inches of rain in the last hour" — both numbers, from one address, verified.
Where Aviso fits
Aviso is a reporting tool for trained spotters — SKYWARN is the training that qualifies you to use it well. If you have already taken your local SKYWARN class, you can submit verified reports through Aviso in about 30 seconds and they route straight to your NWS forecast office. Not yet certified? See our 5-step spotter certification guide.