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30-Day Rain and Dry Days

Continental Africa

Number of Rain Days & Anomaly
Consecutive Dry Days & Anomaly
Total Rainfall & Anomaly
Days Since Rain & Anomaly

Pentadal Period

Available Tools


The GeoWRSI is a geo-spatial, stand-alone implementation of the Water Requirements Satisfaction Index (GeoWRSI), as it is implemented by the USGS for the FEWSNET Activity. The program runs a crop-specific water balance model for a selected region in the world, using raster data inputs. The program produces a range of outputs which can either be used qualitatively to help assess and monitor crop conditions during the crop growing season, or can be regressed with yields to produce yield estimation models and yield estimates. Other tools are available to post-process the GeoWRSI outputs so that they can be used in yield estimation models.


The GeoCLIM is a spatial analysis tool designed for climatological analysis of historical rainfall and temperature data. The GeoCLIM provides non-scientists with an array of accessible analysis tools for climate-smart agricultural development. These user friendly tools can be used to obtain and analyze climate data, blend station data with satellite data to create more accurate datasets, analyze seasonal trends and/or historical climate data, create visual representations of climate data, create scripts (batch files) to quickly and efficiently analyze similar “batches” of climate data, view and/or edit shapefiles and raster files, and extract statistics from raster datasets to create time series.


The Early Warning eXplorer (EWX) software is an interactive web-based mapping tool that allows users to visualize continental-scale rainfall estimate (RFE), land surface temperature (LST) and normalized difference vegetation index (NDVI) data and anomalies at varied time steps and review time series analyses.

EWX Lite

The Early Warning eXplorer (EWX) Lite software is an interactive web-based mapping tool that allows users to visualize time series of rainfall, NDVI, evapotranspiration, land surface temperature and snow water volume, where applicable. The EWX Lite allows users to access the same time series database that drives the standard EWX without having to load raster imagery which can inhibit performance in areas with poor internet connectivity.

Product Documentation

30-Day Rain and Dry Days
(updated April 28, 2021)

Currently, we produce 30-day rain/dry day products and anomalies for Africa and standard products only for other FEWS NET regions.

For products only, the graphic contains 4 images and corresponds to the last date of a pentadal* period. The upper left image (Number of Rain Days) is the number of days, during the last 30 days, in which at least 1 mm of rain fell; that is, a 'rain day' is defined as a day in which the rainfall amount was greater than or equal to 1 mm. The upper right image (Maximum Consecutive Dry Days) is the maximum number of consecutive dry days in the past 30 days that is, the length of the longest dry spell in the past 30 days, where a 'dry day' was defined as a day in which the rainfall amount was less than 1 mm. The lower left image (Total Accumulated Rainfall) is the total accumulated rainfall amount over the past 30 days. The lower right image (Number of Days Since Rain) is the number of days since a 'rain day'; that is, the number of days since the last 1 mm (or more) of rain was recorded for a day. The input data of a 30-day cycle is the daily preliminary CHIRPS available on a pentadal basis.

For products with anomalies (Africa), the same methodology described above is used to generate the image data for rain/dry days, but the graphics produced are four separate sets that consist of a data image (left) and its anomaly (right). The anomaly is the difference between the current day’s image and the average for that day from 2001 – 2015.

A pentad is a group of 5. We use pentadal to define a group of calendar days - generally 5 days. However, because we confine the calendar year to 72 pentads, and each month to 6 pentads, there are not always 5 days in a pentad. The first 5 pentads of each month have 5 days. The last pentad, or 6th pentad, of each month can have as few as 3 days (for example, Feb with 28 days in non-leap years) and as many as 6 days (Jan, Mar, May, Jul, Aug, Oct, Dec, with 31 days). Because of a one-day lag in data reception and processing, products are updated on the 2nd, 7th, 12th, 17th, 22nd, and 27th of each month.