As we move from the dry and hot late summer months to the start of autumn in March, most of us harbour the expectation of a wetter season waiting around the corner. But will it be a good one like the summer rainfall region has experienced since November?
Based solely on average rainfall values of the past, rainfall events tend to become more frequent in Cape Town during March. On average up to 10mm of rain can occur each month from January to March at Cape Town International airport whereafter rainfall values quadruple in April. The rain season of 2016 got off to a fair start with above-normal rainfall in March and April, but the rest of the season’s rains were stunted and the annual rainfall did not even reach the norm.
After last year’s disappointing rains, dam levels were critically low at the start of summer, necessitating strict water restrictions in the Western Cape. At the end of January 2017 all the dams that supply water to the Cape Metro via the Cape Water Supply System were lower than they were the same time last year, except for the Volvlei dam which is also the second largest supply dam to the Cape Metro. The City’s largest water supply dam, the Theewaterskloof Dam near Villiersdorp, is only 34% full.
While it’s still early days, the climate forecast produced by the SA Weather service indicates a slow start to the autumn rains with a risk of below-normal rainfall over the western parts of the Western Cape.
But all hope is not lost; the winter rainfall region in South Africa receives much of its annual rainfall from cold fronts, but during the autumn months of March, April and May, cut-off low pressure systems often contribute to an earlier onset of the rain season. It is not unusual at all to have a wet Easter weekend in Cape Town, as Two Oceans runners of 2012 will clearly remember! It would only take one or two well positioned cut-off lows to give rainfall figures and dam levels a boost early on in the rainfall season.
Until then, the grim truth is that we have reached the hottest time of the year, the height of the fire season as well and with the possibility of below-normal rains during the next few months, there’s no time like right now: let’s save as much water as we can.
Cape Water Supply System: www.capewaterharvest.co.za
Average rainfall climate data and climate outlook: SA Weather Service
Dam levels: www.dwaf.gov.za