aWhere Case Study: Is the rainy season starting in Zimbabwe?
Rainfall over past 30 days. aWhere Weather Data

aWhere Case Study: Is the rainy season starting in Zimbabwe?

Weather Insights: Observed data signals rains are starting

The maps below show precipitation over potential evapotranspiration (P/PET) for the past 7 days as well as the precipitation over the past 30 days. Precipitation / Potential Evapotranspiration (P/PET) is an indicator of the amount of rainfall against the evaporative demands of the environment – values under 0.8 indicate drought stress for maize. The first map (P/PET) shows the conditions over the past 7 days and could signal to farmers when and in what regions they can start planting. The second map shows the rainfall difference from normal over the past 30 days. Blue areas signal wetter than normal conditions.

Much of the country has been fairly dry as shown by above by the P/PET but there is some moisture in southern and central Zimbabwe, signaling a potential stronger start to the rainy season. 

The weekly charts above show the current total precipitation by week compared to the long-term average (2006-2019) for specific GPS coordinates. 

These charts show two weeks of early rainfall in October in these locations followed by 2-3 weeks of 0 precipitation. If farmers planted early after those initial rains, they will have to rely on good rains in the coming weeks to ensure germination.

Over the past 30 days, much of the country was wetter than normal as seen in the map above. As October is still early for significant rains, some farmers may have used the early rainfall as signal to start planting.

What is in the forecast?

The forecast maps below indicate that key agricultural zones will continue to be dry for for the week of 9 – 15 November 2020. There is some rain in the forecast over Mashonaland Central, Mashonaland East, Harare, and Manicaland.

  • Farmers should be preparing their fields for planting in regions where there is expected rainfall.

  • Farmers who have already planted will look for rains to ensure good germination.

The P/PET forecast map below is showing less water stress (green areas on map) over Mashonaland Central, Mashonaland East, and Manicaland for the next 7 days.

All areas need to be closely monitored in coming weeks as farmers begin planting with the first signs of rain. With most of Zimbabwe not having significant rain in the forecast the risk of crop failure is high due to seedling drought of maize

Implications and Recommendations

Zimbabwe has faced increasing frequency and intensity of droughts due to climate change during the past decade. Given the increased need for relief irrigation, refurbishing Zimbabwe’s canal systems and reservoirs is important for future food security. Adapting low-cost watershed management technologies from India will extend the productivity of rainfed agriculture in the face of increased rainfall variability across Zimbabwe.