Tornadoes in South Africa as not as rare as you might think — they can creep up wherever a thunderstorm is brewing‚ especially along the country’s tornado belt.

Data released by the South African Weather Service says most tornadoes in South Africa are observed in Gauteng‚ the Free State‚ KwaZulu-Natal — along a line from Pietermaritzburg to Ladysmith — and the Eastern Cape.

Some 65% of the South African tornadoes are classified as F0 or F1 (light damage)‚ while more than 90% are classified as F0‚ F1 or F2 (considerable damage) or less‚ it said.

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This week a tornado ripped through Tembisa on Johannesburg’s East Rand‚ damaging a shopping mall‚ a hospital and over 200 homes. On Monday another tornado was observed in Magaliesburg.

The South African Weather Service’s chief forecaster Ezekiel Sebego told TMG Digital on Wednesday that it is not yet clear what the magnitude of the two tornadoes are.

Sebego was in Tembisa on Wednesday to assess the damage‚ but said the process did not get very far as the clean-up process had already begun.

“[We need] to estimate the wind speed which was blowing in order to categorise the tornado. We don’t have wind meters everywhere so in order to estimate the wind we look at the pattern of damage‚” he said.

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Sebego said forecasters would now source photographs of the damage to determine the type of wind that was blowing at the time of the tornado.

He added that the weather service’s forecasters had not been out to Magaliesburg to try to categorise that tornado‚ as there had been no reports of damage.

A tornado in Harrismith‚ Free State on November 15‚ 1998 was classified as F2. In January 1999 a tornado in the Eastern Cape’s Mount Ayliff was classified as F4.

Eleven people were injured and more than 50 houses damaged when a tornado hit Grahamstown in the Eastern Cape in 2008.

Certain parts of the Eastern Cape – including the areas of Umzimkhulu‚ Mount Frere and Mount Ayliff – are prone to storms and tornadoes‚ especially during the summer months.

A 2006 Mount Ayliff tornado was referred to by the community as the worst they had ever had. An estimated 20 people were injured and over 100 left homeless.

An analysis of South Africa’s tornadoes indicate that there are hotspots in Gauteng‚ the Free State‚ KwaZulu-Natal and the Eastern Cape. Mountainous areas are most frequently hit.

South Africa’s tornadoes usually occur between November and January‚ though many have struck in spring and early summer and late summer and autumn.

Tornadoes typically occur between 4pm and 7pm. The Tembisa and Magaliesburg tornadoes this week both happened in the afternoon.

Meteorologists rely on weather radar to provide information on developing storms. Currently in the USA‚ scientists can only predict a tornado 20-minutes before it touches down.

Click here to see a map of the tornado belt on the SA Weather Service website.