Temperatures soared in Durban today as berg winds pushed the mercury up to 43°C in some parts of the city.
The South African Weather Service (SAWS) said certain parts of KwaZulu-Natal would experience extremely hot conditions, causing high levels of discomfort.
SAWS said talthough these temperatures were usually associated with heatwaves, today’s heat was a result of berg winds with “high discomfort values ranging from 35-45 degrees Celsius expected”.
Berg winds are the South African name for katabatic wind. This is a hot, dry wind which blows in from the interior escarpment, down from the high central plateau to the coast. The rise in the temperature during a berg wind can be astonishing.
According to World Atlas, katabatic winds are downslope winds. In simple terms, these are winds that carry high-density air from higher elevations down the slope.
The name “katabatic” is derived from the Greek word “katabasis” which means descending.
These winds are formed when the mountain surface becomes colder than the surrounding air, forcing the wind to rush down the slope.
Though generally cold, katabatic winds can also be warm or hot. This is because as the air moves downhill and is compressed, it warms. This means that the katabatic wind would start out cool but become warmer as it moves downhill toward the coast.
According to SAWS, people and animals may experience heat stroke or heat exhaustion with prolonged exposure and/or physical activities.
“All outdoor activities should be suspended. Stop all physical activity. Stay hydrated by drinking lots of water. Listen to the radio or TV for warnings and obey the instructions from disaster management officers.”