Massive swells, gale-force winds and heavy falls of rain are in store for large parts of the Western Cape throughout most of this week, weather forecasters warn.

The first in a series of cold fronts is likely to make landfall later on Monday, with a full week of wild weather ahead.

The SA Weather Service issued a special warning on Sunday that gale-force northwesterly winds, reaching 35 knots, or 65km/h, accompanied by "very rough seas" would stretch from Table Bay to Cape Agulhas, reaching Plettenberg Bay this evening.

The big winds will persist on and off throughout the week, with the windiest days predicted to be Monday, Tuesday, Thursday, Saturday and Sunday.

And farmers in the Little Karoo and Breede River Valley have been warned that the high winds could lead to veld fires in their areas.

The Weather Service also warned that heavy rainfall would hit on Tuesday night in the southwest of the province, spreading to the southern Cape and the interior on Wednesday.

Also on Tuesday, the service warned that "very cold, wet and windy conditions are expected to set in over the western high ground of the Western and Northern Cape Province", with the possibility of snow over the southwestern and southern Cape mountains.

Meanwhile, monster swells are building up in the South Atlantic.