The maps on this page allow you to compare precipitation observations taken at official weather stations with gridded precipitation estimates used for the USDA Pasture, Rangeland, and Forage Program - Rainfall Index (RI). The RI is based on a gridded precipitation dataset developed and maintained by the NOAA Climate Prediction Center. The gridded dataset is developed by statistically interpolating station data from these official networks to a 0.25 by 0.25 degree grid. Each map shows the total precipitation for a 2-month period for the RI (grid) and stations (small circles) that could be contributing to the grid estimates. Use the +/- buttons to zoom in or out and use the cursor to pan to other areas of the map. Moving the cursor over the map will highlight the RI grid value or the station estimates when hovering over a small circle.

Jul-Aug 2019

Aug-Sep 2019

Sep-Oct 2019

Oct-Nov 2019

Nov-Dec 2019

Dec-Jan 2020

Jan-Feb 2020

Feb-Mar 2020

Mar-Apr 2020

Apr-May 2020

May-Jun 2020

Jun-Jul 2020

Jul-Aug 2020

Aug-Sep 2020

Sep-Oct 2020

Oct-Nov 2020

Nov-Dec 2020

How to interpret the station information popup

When you hover over a station (small circle on map) information about this station will popup. The official station name will be listed first followed by the primary and secondary network names to which the station belongs. Most stations will belong to more than one network. Almost all stations listed will most likely contribute observations to the calculation of Rainfall Index values, except for CoCoRAHS. The total precipitation for the 2-month period is shown in green. The number of missing days in the station record is also shown in red in the station info popup. Station records with numerous missing days will lead to large uncertainty in the total precipitation shown.

Network codes and names

Network Code Name Used by RI?
COOP NOAA Cooperative Observers (historical volunteer network) yes
GHCN Global Historical Climate Network (collection of all stations) yes
WBAN Weather-Bureau-Army-Navy (historical airport code) yes
CoCoRAHS Community Collaborative Rain, Hail and Snow Network (new volunteer network) no
FAA Federal Aviation Administration (airports) yes