by Alani Janeke
Early indications of the El Niño-Southern Oscillation (ENSO) predicts that an El Niño phenomenon for this coming summer could be established by spring.
The El Niño-Southern Oscillation describes the state of ocean surface temperatures and the overall connection of climate patterns in the central Pacific Ocean. It consists of two poles, El Niño and La Niña, with a neutral state that can sometimes occur between seasons.
Johan van den Berg, an independent agricultural meteorologist, says the third consecutive La Niña phenomenon came to an end by the end of February 2023. Associated indexes like the Southern Oscillation Index (SOI) have now also shifted out of the La Niña series for the first time in a while.
“The transitional phase causes long-term predictions to be very unsure because there can still be remaining characteristics of La Niña that can influence rainfall. There are strong indications that an El Niño phenomenon will develop from the end of winter to be established by September and/or October. That means the summer season from October 2023 until March/April 2024 2024 should lean more towards El Niño.”
Rainfall patterns for the next couple of months
According to Johan, dry conditions can occur across the eastern parts of the country over the next couple of months, although the central to western parts of the country can still expect rain from the last part of April and especially the first part of May.
If El Niño is established by late winter and the first part of the summer, it is usually responsible for above-average rainfall in the spring and the first part of summer, in other words until the end of October across the central to western parts of the summer rainfall area.
“El Niño is thus not always negative. Oftentimes there is a good rainfall pattern before the summer starts. That is however from around November but especially from December until March when below-average rainfall occurs. The eastern parts of the country are less exposed to the influence of El Niño, with the average deviation for the midsummer months being approximately 10-20%. Over the central but especially the western parts of the country, deviations can be between 30-50% below average during the mid to late summer,” says Johan.
Planting times for summer crops
These deviations can cause a lot of unsureness regarding planting dates for summer crops. “Historically the best planting dates are usually to plant at the normal times until slightly later than usual. Plantations made too early in October will enter their critical reproductive stages during the very dry and hot conditions during December and January. It would still be best to have the tasselling and seed-filling stages take place around February.”
Johan says the problem is that it is sometimes too dry to plant on the best planting dates but, with good groundwater conditions and correct management, planting dates can be manipulated to some extent. It should be taken into consideration, however, that early frost can occur during El Niño seasons, which poses a large risk for late plantations. “However, indications of the best planting dates for different geographical areas can only be given closer to the planting season.”