Exploring Rainfall Trends in Southwest Kenya

The Africa Rainfall Climatology Version 2 (ARC2) dataset provides over thirty years of historical precipitation data across the African continent, making it a valuable resource for long-term rainfall analysis in that region. Today we’re excited to announce that this data is now available on the Planet OS Datahub. Let’s travel across the Atlantic to the southwest region of Kenya and explore historical rainfall trends in the world’s third largest exporter of cut flowers!

Over the past five years, our team at Intertrust (previously Planet OS) has dedicated 20% of our engineering time to making it easier to discover, access and work with high-quality weather, climate and environmental data. Before we release a new dataset on Datahub, our data engineers run various tests and analyses with the data using our API.

We’ve recently explored rainfall data in different parts of the United States, such as Palo Alto and Wyoming. This time we’re crossing the Atlantic and using the Datahub API to analyze daily rainfall in Africa with the ARC2 dataset.

The Africa Rainfall Climatology version 2 (ARC2) is a 30+ year gridded analysis of precipitation using satellite data with spatial resolution of 0.1 degrees. ARC2 uses inputs from two sources:

  1. 3-hourly geostationary infrared (IR) data centered over Africa from the European Organization for the Exploitation of Meteorological Satellites (EUMETSAT)
  2. Quality controlled Global Telecommunication System (GTS) gauge observations reporting 24-hour rainfall accumulations over Africa

Did you know that agriculture is the second largest contributor to Kenya’s GDP?

Most of its agricultural production comes from the fertile highlands of Kenya where they grow tea, coffee, sisal, pyrethrum, corn, and wheat. Surprisingly, Kenya is also the world’s third largest exporter of cut flowers.

To look deeper into the precipitation conditions in Africa, I decided to create an analysis using ARC2 together with the CHIRPS dataset that covers global precipitation. I am focusing on southwest Kenya, its main agricultural area.

Mean monthly values [mm] in southwest Kenya (1983–2017)

Here are some of the things I discovered:

  • 1996 and 2005 were the wettest years in the past 34 years;
  • The monthly mean precipitation showed that summers are always the driest in southwest Kenya;
  • There were some interesting anomalies in 2016. In January and April that year southwest Kenya witnessed higher precipitation than normal. According to the World Weather Attribution 2016 Kenya Drought analysis, this region had indeed more precipitation while rest of Kenya suffered from a serious drought.

For more examples of how you can use the Planet OS Datahub API to acquire subsets of ARC2 and CHRIPS data, then calculate basic historical statistics, check out my Jupyter notebook on GitHub.


The Planet OS Datahub provides free access to high-quality earth science data, and is routinely updated with new datasets. If you’d like to be notified when new data becomes available, follow Planet OS on Medium or subscribe to our email newsletter to receive future updates in your inbox.