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 2.3.3

Updated Yahoo weather API.

Ratings and Reviews

3.4 out of 5
17 Ratings

17 Ratings

funnaddict ,

Good app but...

I have been searching for an app like this to show past precip, so I am excited to find this. However i think it needs two important improvements: 1) ability to adjust the transparency of the precip overlay - without it I can’t really drill down to a location as I can’t see the map under the precip colors. 2) ability to zoom closer than is currently supported - again difficult to get to the location (like a park) at the current max zoom level. Otherwise it looks very promising!

Jeanne-d-Arc ,

App not ready for App Store

Why do people post into the App Store apps that are half finished?

I can’t tell for sure how much precipitation in inches has come in my area in the last couple of days enough to be able to decide whether to turn the sprinklers on this morning or not.

I only get two days a week I’m allowed to turn the sprinklers on, and I don’t want to turn them on and waste money if I don’t need to.

The so-called animation doesn’t do anything, and I cannot really tell what is going on with this app. I am glad that they gave us and them. Imperial units option. But that’s something that should’ve been done before they ever put it on the market in the App Store. The fact that people had to ask for that is appalling, considering we don’t live in Europe. And I still would like the whole app to work before they provide it in the App Store.

It’s very important to find some app that will make it very easy to tell whether I need to turn the sprinklers on or not and that depends on inches of rain reported in the past 24 hours.

I don’t understand why I am supposed to be reporting rain since I would have to stand out with my hands out in my yard all day long to know, and I have no idea whether it rains or not, except when I happened to be standing outside.

ddwillens ,

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.

App Privacy

The developer, University of California, Irvine, has not provided details about its privacy practices and handling of data to Apple. For more information, see the developer’s privacy policy.

No Details Provided

The developer will be required to provide privacy details when they submit their next app update.


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