The South African Weather Service (SAWS) said that the heatwave that has gripped a large part of the Highveld since Sunday, 2 October, will persist over the coming days. Many of the affected areas are registering temperatures in the high 30s with “no immediate prospect of relief in sight.”
READ: 72-hour HEATWAVE warning for FIVE provinces
SYSTEMS CONTRIBUTING TO HOT CONDITIONS
The weather service said a spell of cloud-free dry weather over the last few days has allowed the maximum levels of sunshine to bake the interior of South Africa and led to temperatures increasing incrementally every day.
A very large upper-air high-pressure system – also known as an anticyclone – has also dominated the weather pattern over southern Africa over the last week.
“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,” said the weather service, explaining, which weather systems are contributing to the current heatwave.
HOW IS A HEATWAVE DEFINED IN SOUTH AFRICA?
The weather service indicated that “heatwave” is a term used to describe a period of at least a few days, or longer, during which weather conditions are unusually dry and hot over a particular area.
The term is used across the world, however, each meteorological agency has a custom definition of a heatwave to suit local conditions.
In South Africa, a heatwave is declared when “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, the weather service regularly updates its national heatwave map which gives an indication of the temperature threshold that needs to be attained or exceeded across the country.
The current heatwave conditions are expected to continue in parts of Gauteng, Free State, North West and Mpumalanga until Friday, 7 October.
As a safety precaution, the public is encouraged to stay hydrated by drinking water regularly, avoid over-exertion, and wear sunblock, sunglasses and hats.
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