12 Jan 2015

The Department of Meteorological Services warns the public of extreme hot conditions over most parts of the country in January.

Maximum temperatures may reach about 40 degrees Celsius or more over the Northern-Kgalagadi as less rains are expected in that area while other districts would experience temperatures of between 36° C and 40 degrees Celsius.

In an interview Principal Meteorologist Mr Radithupa Radithupa said the public was therefore advised to exercise care and take precautionary measures to mitigate the impacts of excessive heat.

Mr Radithupa said January was usually termed a dry spell as there was less or no rains as over the South West Indian Ocean around Madagascar tropical cyclone season started to develop.

He said in that region there tended to start a lot of activities in terms of rains across Southern Mozambique through Zimbabwe and a lot of moisture was dragged along those systems taking it back to those channels and Botswana remained dry for that period.

Mr Radithupa said that it was during that time that over Botswana, the high pressure system or anti cyclone developed.

“These high pressure systems depress all cloud developments in terms of rainfall,” he said, adding that within this strength of anti-cyclone from the surface into the upper atmosphere there was an inversion and this was where temperature begin to increase.

He noted that if one looks into the climatological data, the highest temperature recorded in January at Tsabong in 1970 was 42 Degrees Celsius and in 1966, Francistown recorded 40.6 Degrees Celsius while Gaborone recorded 42 in 1989.

Mr Radithupa advised farmers who were weeding their farms and those looking after their livestock to always put on a hat and carry water with them at the same time avoiding prolonged stay on the sun adding that they should work early in the mornings and late in the afternoons.

Explaining some meteorological terms, Mr Radithupa said heat wave was a prolonged period of excessively hot weather, which may be accompanied by high humidity, especially in oceanic climate countries.

He said it was measured relative to the usual weather in the area and relative to normal temperatures for the season. Mr Radithupa said temperatures that people from a hotter climate consider normal could be termed a heat wave in a cooler area if they were outside the normal climate pattern for that area.

The term is applied both to routine weather variations and to extraordinary spells of heat which may occur only once a decade or century, he said. Mr Radithupa further said severe heat waves had caused catastrophic crop failures and sometimes human deaths from hyperthermia. ENDS