The rand slipped to a 6-month low against the dollar early on Wednesday, with investors waiting for local retail sales figures and the US Federal Reserve’s policy decision later in the day.
At 0615 GMT, the rand traded at 13.36 per dollar, 0.3% weaker than its close on Tuesday.
The unit is trading at its weakest level since December 15, according to Thomson Reuters data.
South African assets have been hurt by disappointing first-quarter gross domestic product data and an unfavourable external backdrop which has seen global investors pull back from emerging markets.
Statistics South Africa publishes April retail sales data at 1100 GMT, which will give more evidence on the performance of the economy at the start of the second quarter.
The Fed is widely expected to raise interest rates for the second time this year after a move in March, but the bigger question for investors is the outlook for future monetary tightening amid an ongoing economic expansion.
In fixed income, the yield for the benchmark government bond due in 2026 was up 6 basis points to 9.08%, reflecting weaker prices.