Johannesburg - Mosquitoes in July, short sleeves and not a sign of frost in the mornings.
That was winter, and now it’s just a memory as Joburg is about to experience its first heatwave of this summer, with temperatures predicted to reach 30ºC.
All can agree that it has been a wimpy winter, but how warm was it? The South African Weather Service has crunched the numbers.
The average difference in the maximum temperature between May and August this year and last year is just 0.1ºC.
This year is the winner, recorded at 21.2ºC. Last year, the temperature was recorded at 21.1ºC.
And as for those chilly nights? The minimum for Joburg this year between May and August was 5.025ºC. Last year it was 4.7ºC.
To find a winter as warm as this year, according to the weather service, you need to go back to 2005, when the average was also 22.2ºC.
Joburg didn’t feel the big freeze this year, according to Cobus Olivier, a researcher at SAWS, because those cold fronts that usually head up towards the highveld kept on missing us. Cold fronts would fizzle out in the sea.
The culprit for this could be a weather mechanism south of South Africa known as the southern annular mode, which lurks between the latitudes of 45º and 60º. Many weather researchers believe that the southern annular mode regulates cold front activity. The mechanism was discovered in the 1970s.
Talk to farmers and the lore is that a warm winter often brings a dry summer, with limited rainfall.
That is not the case, according to Olivier.
“Our rainfall is influenced by summer weather systems. Winter systems have no effect on this,” he said.
Rain-generating weather systems are to the north of South Africa in the tropics, he said. And it looks like it is going to be a while before the real rains set in and those highveld thunder clouds can be seen once again stacking on the horizon.
By observing the global weather patterns, the long-range forecasters at the weather service have come up with when they think the serious rains will come.
“Currently, we believe it is going to start off drier and the wet weather is going to come later in the summer,” he explained.
“November, December and January are looking like having a high probability of rain.”
Eskom was one organisation that was happy about the mild winter. At the beginning of winter, there were warnings of possible rolling blackouts if electrical demand outstripped supply.
A couple of winter nights were tight, said the chief executive of Eskom, Brian Dames. “The highest peak this winter was 35 421 megawatts on June 11, which was only slightly lower than 35 894MW recorded on August 7 last year.
“This can be attributed to a relatively mild winter compared to last year,” he said in a statement.
While the weather bureau does predict a drier start to summer, thunderstorms are forecast in some places today.
This is as Joburg temperatures are predicted to go up to 27ºC on Friday and to climb at the weekend to a possible 30ºC on Sunday and Monday.
The Star