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Statement from SA Weather Service spokesperson, Garth Sampson
Heat wave conditions are expected over the entire Eastern Cape for tomorrow 17 January to Thursday 19 January 2012.
Temperatures along the coastal regions will be in the early 30's and over the interior, mid to high 30's.
What is a heat wave?
A heat wave is a prolonged period of excessive heat. Technically, a heat wave is when temperatures are 5 deg C or more above the average of the hottest month and that carries on for 3 days or more.
What is the cause of this particular heat wave?
There is a strong, well developed upper high which is causing subsidence (downward moving air) over the western half of the country. This upper high is set to stay there as there is a tropical depression over the Indian Ocean affecting kwa-Zulu Natal and should not affect the Eastern Cape. This subsiding conditions are causing clear conditions and the warming of the air due to the downward motion. This will result in high temperatures, which is 5 or more degrees higher than the monthly average maximum temperatures for the 3 days, hence a heat wave.
Are heat waves unusual?
Heat waves are rare occurrences but not unusual during the spring and summer seasons. They can also happen anywhere in the country.
What advise does SAWS give to the affected communities?
Outdoor physical activities must be avoided, especially for the young and elderly.
Stay in a well-ventilated or air conditioned room.
Take frequent breaks if you have to work outdoors.
People are advised to drink enough water/fluids to avoid dehydration.
Avoid black/dark-coloured clothing because they absorb the sun's rays.
What will bring the cooling to end it?
On Thursday 19 January the surface trough is starting to bring sufficient moisture down over the central and western interior from the tropics. With the high temperatures the influx of moisture will trigger widespread thunderstorms, Thursday evening and overnight and on Friday, which will end the excessive heat.
