Read more
Experts warn colder nights and frost are likely due to wet soil from recent rainfall.
Picture: iStock
The first of the winter cold fronts moving over parts of the country is a preview of the rest of the season.
Vox Weather meteorologist Annette Botha said it was officially winter in South Africa, although some argue winter only starts on 21 June.
The first of two cold fronts moving in over the country with chilly temperatures are a taste of what’s to come.
Cold front a taste of what’s to come
“A stronger, more intense cold front is set to hit on Saturday. On Friday it will be windy in the interior with gusting northwesterly winds ahead of the strong cold front expected to move over the Western Cape,” she said.
Vox Weather meteorologist Michelle du Plessis said there was a difference between meteorological and astronomical seasons.
“Meteorological seasons are based on annual temperature cycle and follow the calendar, so every three months is a new season,” she said.
ALSO READ: SA Weather forecasts cool and fine weather with rains and winds
“Astronomical seasons are based on the position of the earth relative to the sun and use solstices and equinoxes,” she added.
Du Plessis said higher rainfall didn’t necessarily mean lower temperatures in winter.
“Not necessarily colder overall – but wetter soils can play a role in how temperatures behave at night.
Wetter soil from recent rainfall plays role in night temps
“When soils are wetter from good autumn rainfall, they to lose heat faster overnight, especially under clear skies. This can lead to colder nights and more frequent frost, even if daytime temperatures remain fairly mild.
“So while it doesn’t mean we’ll have a colder winter in general, the risk of frost can increase, particularly in inland regions like the Free State, Gauteng and the highveld, where frost is already common.”
Du Plessis said after a wet summer or autumn, the soil holds onto more moisture going into winter.
ALSO READ: The cold front is here! Here’s how long it will last for [VIDEO]
“That doesn’t mean the whole winter will be colder. Temperatures depend more on the weather systems that move over the country and whether we get bursts of cold, subpolar air, but it can make nights feel colder,” she said.
Du Plessis said historical climate patterns from the SA Weather Service show frost can occur even in warmer-than-average winters, especially when skies are clear and soil moisture is high. This allows surface temperatures to drop rapidly at night.
“The latest seasonal models are showing above-average temperatures overall this winter. We’ll still get those icy cold snaps like every year,” she said.
Above-average temps overall this winter
Last month, the SA Weather Service issued the seasonal climate watch from May to September. According to the seasonal forecast, the El Nino-Southern Oscillation has returned to a neutral state and will be in a neutral state for the foreseeable future.
The southwestern and the southern and eastern coastal areas are expected to receive mostly below-normal rainfall early, midand late-winter.
The minimum and maximum temperatures are expected to be above normal for most parts during the winter, with the exception of the southern coastal areas that are expected to be below normal in parts.
