Unless it starts to rain with serious intent in the remaining ten weeks of the summer rainy season Eastern Gauteng is headed for its driest summer of the last 25 years.

Our rainfall statistics are measured from the start of the rainy season on 1 September each year, to 31 August the next.

From the start of the rainy season last September to the middle of March we recorded only 396mm of rainfall on the East Rand. This is way less than half last year’s total of 931mm. It is also lower than the previous driest year, 2006/7, when we recorded 456mm.

So, to avoid being the driest year in a quarter of a century a further 60mm or more needs to fall. On past performance this is doable.

The average total rainfall for April, May and June is about 85mm. The average total rainfall for the entire rainy season over the past 25 years stands at 809mm.

E Gauteng is getting wetter

Interestingly, while the 2023/4 rainy season is going to be one of the driest – if not the driest – years, the climate over East Gauteng has been getting gradually wetter over the years (see trendline). Indeed, year on year the trend has been very much upward, having increased by about 250mm a year over the quarter century. That excludes this year’s partial figure of only 395mm to date.

Rainfall (blue line) from the 1999/2000 season to the 2022/2023 season (ie, excluding the current season’s partial figure). The trendline for the same period appears in black.

While localised rainfall is one thing, the levels of dams feeding water to Gauteng’s households is another.

Gauteng’s major source of water is the Vaal dam. This is fed both by water from Lesotho and from its main catchment area in southern Mpumalanga (Standerton/Ermelo). So rain over Gauteng has very little bearing on the level of water in the Vaal Dam.

Of greater immediacy to Gauteng are smaller dams with local catchments. These include Roodeplaat, Bon Accord, Bronkhorstspruit and Rietvlei. Hartbeespoort to the west is fed largely by rivers sourced in Gauteng (eg, Crocodile and Hennops), but feeds its water further west.

Dam levels dropping

Water usage increases dramatically in heatwaves, of which Gauteng has had a few this summer. In mid March dam levels generally were dropping by about one percent a week.

This does not bode well for the dry months ahead, and particularly not for the Spring season later this year if the dry weather pattern persists.

Of course, dam levels and municipal water are of little value to many smallholders and rural dwellers. They rely on boreholes for their water, and rainfall for their crops and pastures.

Expect high fodder prices

A dry summer season, therefore, means less in the way of grazing. This will mean more fodder needs to be bought and brought in from outlying areas.

Smallholders with livestock can therefore expect to pay higher prices for their feed as demand starts to outstrip supply.

It is advisable, therefore, to lay in a supply of bales early, storing it under cover until required. By so doing the higher end-of-season prices will be avoided.

Main image: Heatwaves and little rain lead to wilted crops. Image by Rasbak, Wikimedia Commons

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