Rainfall outlook for Zimbabwe 2024/25 season
Last week, we shared the Twenty-Ninth Southern Africa Regional Climate Outlook Forum (SARCOF-29) rainy season forecast for the SADC region. This week, we are sharing our own national forecast, presented and shared by our Meteorological Services Department.
The Meteorological Services Department of Zimbabwe (MSD) annually convenes a National Climate Outlook Forum (NACOF) in September, where the seasonal rainfall forecast for the upcoming rainfall season is presented to national stakeholders. This follows the regional forum, Southern Africa Regional Climate Outlook Forum (SARCOF).
As the SARCOF statement covers relatively large areas, it may slightly differ from our NACOF statement, as it may not fully account for all the factors that influence our national climate variability.
Zimbabwe’s forecast
The 2024/2025 rainfall season coincides with a weak La Niña phase. There are prospects of better rainfall for the country from the second sub-season until the end of the forecast period, which spans from November-March. The forecast for the 2024/2025 rainfall season is based on the accumulated rainfall for each sub-season, without taking into consideration its temporal distribution.
The rainfall forecast for the 2024/2025 season covers the months October 2024 to March The forecast is demarcated into four sub-seasons, October-November-December (OND), November-December-January (NDJ), December-January-February (DJF) and January-February-March (JFM). This year the country has been divided into dynamical zones following the forecast signal in each sub-season. Areas indicating the same forecast signal are categorised into one zone.
The main global climate driver, the El Niño Southern Oscillation (ENSO), is currently in the neutral phase and is expected to transition into a weak La Niña phase starting October 2024 reaching a peak in the DJF sub-season. The La Niña phase has a higher chance of normal to above-normal rainfall over the southern parts of the SADC region including Zimbabwe.
However, the country is expected to receive normal to below-normal rainfall for the period October 2024 to December 2024. An improvement in the rainfall performance is expected for the sub-seasons November-December-January (NDJ) 2024-2025, December-January-February (DJF) 2024-2025 and January-February-March (JFM) 2025 with normal to above-normal rainfall anticipated across the country.
Terminology
- Normal – long-term average rainfall received in an area
- Normal to below-normal – cumulative rainfall most likely to be within the long-term average range with a chance of going below this range
- Normal to above-normal – cumulative rainfall most likely to be within the long-term average range with a chance of going above this range
- Above normal - cumulative rainfall most likely to be above the long-term average range with a chance of falling within the long-term average range
- Below normal - cumulative rainfall most likely to be below the long-term average range with a chance of falling within the long-term average range.
Above-normal rainfall is defined as rainfall amount exceeding 125% of the long-term average (normal rainfall) of the climatic period from 1981-2010; below-normal is defined as rainfall amount less than 75% of the long-term average; normal to below-normal rainfall falls within 75% to 100% range of the long-term average; while normal to above-normal rainfall is defined as rainfall amounts falling within 100 to 125% range of the long-term average.
The period October 2024 to March 2025 is the main rainfall season over most parts of the country. Owing to the differences in evolution patterns in the predominant rainfall-bearing systems, the rainy season has been subdivided into four overlapping three-month periods (October-November-December, November-Decmber-January, December-January-February and January-February-March or OND, NDJ, DJF and JFM).
Rainfall outlook for the October to December (OND) 2024 period
The country is expected to receive normal to below-normal rainfall.
Rainfall outlook for the November to January (NDJ) 2024/2025 period
The country is expected to receive normal to above-normal rainfall.
Rainfall outlook for the December to February (DJF) 2024/25 period
The country is expected to receive normal to above-normal rainfall.
Rainfall outlook for the January to March (JFM) 2025 period
The country is expected to receive normal to above-normal rainfall.
Implications for the rainy season
The normal to below-normal rainfall for the first sub-season (OND) will likely result in a late start to
the season in places.
The tropical cyclone forecast will be availed as the rainfall season progresses.
Given the intra-seasonal variability of the rainfall in any season, the following recommendations are being proposed according to the MSD:
- The cloud seeding programme to be implemented during the season to enable rainfall enhancement if required.
- Use of irrigation to maximise on the temperatures during the first half of the season (October to December) and during periods of prolonged dry spells.
- Contingency plans for extreme events such as violent storms, prolonged dry spells, flash floods to be in place.
- Water harvesting and conservation programmes to be maintained given the intra-seasonal rainfall variability.
- Agricultural activities such as planting and fertiliser application should be guided by the 10-day weather forecasts.
The Meteorological Services Department will continue to monitor seasonal climate indicators which influence Zimbabwe’s rainfall as they evolve. Thus, the seasonal rainfall predictions will be updated on a monthly basis beginning end of October. In addition to this forecast, there will be daily weather forecasts and 10-day weather bulletins that will account for short-term variabilities such as dry and wet spells.
As Zimbabwe gears up for the 2024/2025 agricultural season, staying informed and prepared will be key to maximising crop yields and ensuring food security.
* The Meteorological Services Department falls under the remit of the Ministry of Environment, Climate and Wildlife.