A bitter winter blast is heading for South Africa, with forecasters warning of snow-covered mountain passes, flooding rain and rough seas.

The South African Weather Service (SAWS) is warning of bitterly cold, wet and windy conditions during the first week of June.

While Monday and Tuesday are expected to be partly cloudy and cold, South Africans should brace for a chilly week, with snow forecast in several areas.

According to the forecaster, very cold conditions and rainfall are expected over the central and eastern interior of the Western Cape, as well as the southern parts of the Namakwa District in the Northern Cape, from Wednesday.

"Light snowfall is expected over the mountain tops of the central and eastern parts of the Western Cape, and the higher-lying areas of the southern Namakwa District during this period," SAWS said.