Heatwave to persist in days ahead

The SA Weather Service (SAWS) says heatwave conditions are expected to continue over Gauteng, the eastern parts of North West, the eastern highveld of Mpumalanga and the south-western bushveld of Limpopo up to and including Friday.

The service said many parts of North West, northern Free State, Gauteng and the eastern highveld of Mpumalanga are registering maximum temperatures in the high 30s, with no immediate prospect of relief.

“SAWS has determined, particularly for SA conditions, that for a heatwave to be declared, “the maximum temperature at a particular station should reach or exceed the average maximum temperature for the hottest month for three or more consecutive days.

“For convenience, SAWS regularly updates a national heatwave map, indicating the temperature threshold which needs to be attained or exceeded in all areas across the country. A heatwave describes a spell of at least a few days, or longer, of unusually hot, dry conditions over a particular spatial area. While this term is commonly used worldwide, the meteorological agency for each country will typically customise their definition of a heatwave to suit local conditions,” it said.

The service said dry and cloud-free weather over the past few days has allowed maximum levels of sunshine (insolation) to arrive over the interior of the country, with temperatures becoming incrementally higher every day.

It said a very large upper air high-pressure system, (or anticyclone) has dominated the weather pattern over the southern African subcontinent in the past week, extending over much of Namibia, Botswana and the northern half of SA.

“Apart from this feature blocking the arrival of tropically sourced moisture, and thus delaying the onset of our summer rains, upper air highs are well known to be associated with large-scale air stability and sinking air masses. Such systems inhibit thunderstorm development, but perhaps more importantly, in this case, the sinking air heats up quite dramatically.” 

SAWS advised South Africans to ensure they stay hydrated by regularly drinking water.

“It is also best to avoid over-exertion when exercising (sport or leisure activities). In particular, infants and small children should be regularly supplied with fluids as dehydration can set in very quickly. Similarly, the aged and infirm should also take great care during heatwaves so as not to over-exert themselves. Being cognisant of the abundant sunshine during heatwave episodes, the wearing of hats, preferably with a wide brim, and eye protection in the form of sunglasses, is highly recommended. Liberally apply sunblock to all exposed skin when spending time in the sun,” it said.

It is also recommended to stay indoors or in shade and out of direct sunshine between 11am and 3pm.

The weather service said it will monitor developments relating to the weather system and will issue updates.

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