Welcome to the iRain app. The app is licensed to the Center for Hydrometeorology & Remote Sensing (CHRS) at the University of California Irvine (UCI).

iRain provides access to real-time global high-resolution (~4km) satellite precipitation products from the PERSIANN-CCS (Precipitation Estimation from Remotely Sensed Information using the Artificial Neural Networks - Cloud Classification System), which has been developed by the research team at CHRS. The building block of iRain rests on the satellite precipitation estimates generated by the PERSIANN algorithm which has been under development for over two decades. More detailed information about PERSIANN-CCS can be found at

iRain allows users to visualize real-time global satellite precipitation observations and track extreme precipitation events globally. Users can also use the crowdsourcing functionality of the app to report their local rainfall information to supplement our data.
The web version of iRain is hosted at:

The iRain system is the product developed by Dr. Phu Nguyen, Assistant Adjunct Professor in the Center for Hydrometeorology and Remote Sensing (CHRS) at UCI and his team, which includes a dedicated group of mostly undergraduate students, including Phat Huynh, Thanh N. Palacios, Hoang Tran, and April Huie.
The iRain mobile app was developed by David Furman.

Financial support of the following agencies is acknowledged:

- NASA funding resulted in the development of the PERSIANN algorithm and several of its variations.
- ICIWaRM of the US Army Corps of Engineers has provided a major part of support for Mr. Dan Braithwaite, Programmer Analyst III at CHRS.
- The US Army Research Office’s support has resulted in additional refinement of the PERSIANN algorithm
- Cooperation with UNESCO’s G-WADI program has been critical to the dissemination of data worldwide.
- NOAA funding through the Climate Data Record (CDR) program resulted in the PERSIANN-CDR dataset.

The following members of CHRS (former and current) are greatly acknowledged.
Kuolin Hsu, Xiaogang Gao, Bisher Imam, Dan Braithwaite, Hamed Ashouri, Andrea Thorstensen, Scott Sellars, Ali Behrangi.

Special thanks to Hien To, Ph.D. student at USC, for his contribution on the crowdsourcing technologies.

Soroosh Sorooshian, Ph.D. NAE
CHRS Director

What's New

Version 2.3.0

• Subscribe to rainfall notifications by pressing and holding on the map!

• Added a button to share iRain from its settings page.

• Bug Fixes

Ratings and Reviews

Fantastic app!


It has real-time satellite precipitation data, which is great, but then on top of that the whole crowdsourcing concept is very cool. You can request real time information from other users anywhere in the world, and contribute to a rain/snowfall observation record.

Good app for rain totals


Very nice app. The one criticism I have is that there should be a way to turn off the crowdsource layer, or at least filter out the items with "no precipitation." Here in Southern California the map is literally filled with useless "no precipitation" markers.

And I agree with the other reviewer about mm vs inches. I'd much prefer to see this in inches.

A promised app


This app is improved over the time and being useful. Fantastic working and progressing. I hope to see more feature in the new update.


University of California, Irvine
57.4 MB
Requires iOS 10.0 or later. Compatible with iPhone, iPad, and iPod touch.
Age Rating
Rated 4+
© CHRS UC Irvine


  • Family Sharing

    With Family Sharing set up, up to six family members can use this app.

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