Explaining the January 2023 drought 'anomaly'

Dr Johan Malherbe, a researcher in soil, climate and water at the Agricultural Research Council, explores the effect of a very dry January on the rest of the planting season.

This January was very dry over most of north-eastern South Africa, including a large part of the summer-grain production region. Very little to no rain

fell between 5 and 29 January over the northern half of the grain-production region in particular.

These conditions highlighted the absolute dependence of dryland maize cultivation on regular and adequate rainfall during summer.

With 2022/23 the third consecutive summer during which La Niña conditions dominated global atmospheric circulation patterns, the negative effects of too much rain, such as waterlogged lands, have been much more in the news than the negative effects associated with drought.

La Niña is the colder counterpart of El Niño in the broader El Niño-Southern Oscillation (ENSO) climate pattern, leading to intense storms in some places and droughts in others.

Historically, though, the limiting effect of drought on maize production far outweighs that of too much rain. This was demonstrated during the 2015/16 drought when maize production dropped by roughly 40% relative to the previous summer.

The dry conditions in January occurred during an otherwise wet summer. Rainfall over the summer-grain production region was significantly above the long-term mean (see Figure 1). However, sunny and dry conditions set in from early January and continued until 29 January over the northern half of the region, when scattered thundershowers returned.

Despite the return of rainfall to most of the region, total rainfall for the month fell dismally short of the long-term mean (see Figure 2).