A rare snowfall dusted Johannesburg and other high-lying parts of South Africa on Monday, with weather services warning of potential road closures and dangerously cold temperatures.

Residents in the business hub woke up to snowfalls lightly covering rooftops and gardens as a cold front that hit the country late last week morphed into a weather system called a "cutoff low."

At a Johannesburg kindergarten, excited children made snowballs and attempted to catch flakes with their tongues -- some having never witnessed snow before.

"We last saw this type of weather in 2012," Puseletso Mofokeng, a senior forecaster at the South African Weather Service (SAWS), told AFP.

Mofokeng said snow was reported across southern parts of Johannesburg's Gauteng province and was expected to continue falling throughout the day, also hitting high-lying areas of the Eastern Cape and KwaZulu-Natal provinces.

"Roads may be closed," he said.

Johannesburg lies at an altitude of more than 1,700 metres (5,600 feet) and is in the peak of the southern hemisphere winter.

But snow in the city remains a rare event -- prior to 2012, heavy snowfall occurred in 1996, Mofokeng said.

"It's been such a long time, I feel so happy," said Lerato Matepese, a Johannesburg resident.

SAWS warned that icy temperatures posed a risk to street dwellers in a country where poverty remains widespread.

Rough seas and strong winds were also expected to create hazardous conditions for small vessels off South Africa's eastern coast.