Sterkstroom farmer looks at 150 years of rainfall records

Sterkstroom farmer Ian Hansen says he has recorded rainfall for their farm area spanning 150 years from 1874 to the present.

He finds significant patterns in the figures. He says: Periods of aboveaverage rainfall years are consistently followed by a period of below-average rainfall years. The length of these periods or cycles varied from two to 10 years. This pattern was consistent over the past century and a half

The last period of below-average rainfall occurred in 20182019, during which the rainfall was 21% below the average.

This was followed by four consecutive years of above-average rainfall (2020-2023), which is the highest on record since the 19401943 period when the above-average rainfall was 29%.

Given that we are now in a period of below-average rainfall, the question remains: what can we expect?

While the SA Weather Service, like other meteorological agencies worldwide, can only provide predictions for the next six months, Hansen's analysis suggests that a sustained period of below-average rainfall, lasting from four to six years, is highly probable.

By examining historical data, [I] have identified patterns that can indicate the likely duration and severity of this impending dry spell. From the analysis of the past figures over the period 1874-2023 indicates that one can expect only 10% below-average rainfall.

However, in the four to six years ahead, one could expect mostly below-average rainfall with one extreme year below average, with at least one year above average.

Based on the analysis of rainfall patterns from 1874 to 2023, it appears that one can expect roughly a 10% belowaverage rainfall in the coming years.

However, within the next four to six years, [my] analysis suggests that mostly below-average rainfall can be expected, with one extreme year of significantly low rainfall and potentially one year of aboveaverage rainfall. The analysis points to a predominantly dry period with the potential for one year of reprieve.

The “extreme'” year of low rainfall could be this year, with estimates predicting between 15-20% below-average rainfall.

This is largely due to the lack of rainfall in February, and indications suggest a dry spring and potentially belowaverage rainfall in November. A normal summer rain pattern may follow. The year after that could potentially see aboveaverage rainfall.

However, the analysis indicates that the years after that will likely remain below average. By the end of 2025, we may have a more accurate picture of the rainfall patterns in this period.

The current heatwave and El Nino phenomenon have resulted in little rain in February and early March, impacting maize crops. This could impact negatively on mieliemeal prices.

With forecasts predicting belowaverage rainfall for the next four years, we may see a repeat of an El Nino year. However, we hope the severity of such an event will be mitigated to reduce its economic damage.