Rainlog.org is a cooperative rainfall monitoring network for Arizona developed at the UA by SAHRA and Cooperative Extension. SRP has been a leading partner in supporting rainlog.org. Data collected through this network will be used for a variety of applications, from watershed management activities and weather reporting to hydrologic research and drought planning at local, county, and state levels.
All one needs to participate is a rain gauge and access to the Internet. We seek volunteers with rain gauges installed at their homes, who are willing to report daily total rainfall amounts through an online data entry form.
Official rain gauges in Arizona are few and far between. The large gaps in coverage are a particular problem where precipitation amounts are highly variable due to topography and seasonal weather patterns. This is especially true during the monsoon season, when thunderstorms can produce heavy rainfall that is very localized.
All data posted by volunteers is available in real-time in maps and time series graphs through the data tab at the top of the web page. These maps are useful in tracking high-resolution variability in precipitation patterns and potential changes in drought status. As more people participate and more information is gathered, the resolution of the maps will improve.
Just go to www.rainlog.org, click on the "register" button in the upper right, and follow the instructions. It's quick and easy.
If you don't have a rain gauge, you can find information on different types of gauges on the rainlog site. If you want an inexpensive, fairly accurate gauge and can't find one at a nearby retail outlet, one can be purchased through .
Rainlog asks volunteers to make daily observations as close to 7 am as possible (anywhere from 7am to 10am is good for recording data) for the previous 24hr period. This means that a recording made this morning will be reported as the daily total for yesterday. For example, if you read your rain gauge at 7am on July 23rd it will be displayed as the daily observation for July 22nd. The reason we have it structured this way is to be consistent with the way that the National Weather Service displays their volunteer observations. Reading the gauge in the morning ensures that if you get any nighttime precipitation you do not have to stay up and read your gauge at 12am. It isn't a perfect approach but ensures consistency between the different groups that collect rain data. So, check to see if the data you reported is displayed as the previous day.
At this point in time, it would be best to use the Rainlog coordinates for right now to make sure that your location displays correctly on the Rainlog maps. Your coordinates determined by GPS are undoubtedly more accurate. The rainlog tool may be using a different datum. We have had some problems with the mapping tool, but as of now, it would be best if you kept to the rainlog coordinates.
When there is snowfall, sleet, or hail, take your rain gauge indoors and wait until it melts and record the amount of water that has collected in your gauge. Additionally, make certain to report in the Additional Comments field the type of precipitation that occurred.
We have to assume that our rain loggers have normal lives and so cannot always be around to read their rain gauges. I would urge you to sign on, even if you'll be gone for a couple weeks from time to time.
The problem for us is that when it rains in part of an area, and we get no report from some loggers, we don't know how to interpret that - did they get no rain, or were they not there to read the gauge?
Our web site allows one to enter "absent" or "lost" when rain gage is lost due to rain gauge malfunction or other mishaps.
In addition to accepting daily rain totals, the site also accepts monthly totals. So if you really want to know about the rain at your home while you're gone for a couple weeks, you could do what those who only report monthly totals do - put a little mineral oil in the gauge. Then when it rains, the water drops below the mineral oil and doesn't evaporate. At least, not very much. There are instructions on this on our web site as well.
Mineral oil is a byproduct of distilling gasoline which is also used for health care uses. More specifically, mineral oil is just baby oil without the fragrance added. Mineral oil is used as it does not evaporate, remains clear, and lets water readily pass through it. Best of all, mineral oil is inexpensive and is found at most drug stores.
Mineral oil is only necessary if you plan on capturing the totally rainfall over a month and should not be used for daily recordings. To avoid build up of dirt and insects, one should clean their rain gauge readily. Soap and water will clean it out just fine.
Rainfall records prior to 2007 are very helpful and greatly appreciated. If you have them in electronic format, please email them to help@rainlog.org.
Alternatively, if you have paper records, please contact us at help@rainlog.org and we can provide snail mail instructions.
After you have entered in your rainfall data, view a map with your data point on it. Click on the data point and a graph of rain for year to date will pop up. Click on the graph to get a larger version of the graph. If you have rainfall data entered for previous years, you can view this as well. Click on "show report's compact version." You can print this out and have a nice summary of your precipitation data for that year which includes a graph on top and a calendar below.
If you are not registered with RainLog or want to view a precipitation summary of another area, you can click on any other location and follow the same process.
Dew found in the rain gauge should not be counted as precipitation because it is difficult to tell whether dew is falling across the entire landscape.