Sustained rainfall in Gauteng is causing flooding in parts and slick roads, prompting a caution for drivers, while Afropunk organisers say the show will go on.

The rain, which brought relief after extended, intense heat ahead of Christmas 2018, is expected to continue into the first week of 2019.

Gauteng Weather also issued a weather alert for heavy rains leading to road flooding in parts of northern Johannesburg on Monday.

It said the flood-prone areas in Gauteng are Alexandra, Bedfordview, Benoni, Centurion, Edenvale, Fourways Johannesburg central, Kempton Park, Soweto, the N3, M1 and R23 highways, and all areas around the Hennops and Jukskei rivers.

Gauteng Weather also said Pretoria and Johannesburg should expect plenty of  rain on Monday and Tuesday and the rains will subside on Wednesday.

The South African Weather Service also issued a warning for floods in Sedibeng and Westonaria in Gauteng.

In addition, the South African Weather Service issued a flood watch for the Gert Sibande district municipality in Mpumalanga from 11am to midnight. The district municipality has 20 towns which include Secunda, Standerton, Badplaas, Leandra and Balfour.

Meanwhile, as revellers stand by to see in the new year, organisers of the Afropunk event at Constitution Hill are encouraging ticket-holders to attend, despite the weather.

In Newtown on New Year's Eve, a countdown to see in 2019 is scheduled to proceed, with the metro saying police will be on duty to ensure all goes smoothly.

Meanwhile, Johannesburg mayor Herman Mashaba has called on motorists to drive safely.