The rand will lose half of the dollar's 7% gains since the start of the year over the next 12 months, pressured by fiscal tightening and weak growth, according to a Reuters poll released on Wednesday.
The rand has outpaced emerging market currencies since the start of the year, boosted by external developments such as the Federal Reserve potentially more "patient" in raising interest rates and a revitalized climate in US-China trade talks.
However, in 12 months the rand should have weakened more than 3% to 13.85 per dollar, although this average forecast is 58 cents stronger than last month.
"There are still notable local risks in line with moderate growth and fiscal challenges that require caution," said Christopher Shiells, emerging market analyst at Informa Global Markets.
In the October budget review, South African Finance Minister Tito Mboweni predicted broader budget deficits and slashed growth forecasts that focused spending on infrastructure, manufacturing and agriculture to boost the weak economy.
"These challenges could lead to a downgrade of Moody's sovereign credit rating in March if the 2019 budget does not calm any lingering worries," Shiells said.
The budget should be announced in about two weeks, followed by a review by Moody's. Moody's is the only major agency that still holds South Africa's investment grade debt.
A debt downgrade dominated by Moody's will trigger forced capital outflows from passive investments.
The Shiells have also added to the risks national elections in May that carry "popular political movements and stalled reforms".
Analysts were still optimistic about the currency's support from overseas, even when local fundamentals were disappointing.
The most optimistic analyst in the sample said the rand would be trading at 12.63 per dollar in a year, while the lowest suggest that the currency could fall to 15.50.
Last month, Fed policymakers indicated they were halting a rate hike that began in December 2015 as the US central bank tries to find out how much a weakening global economy could drag into the United States.
South Africa's rates are expected to rise 25 basis points to 7.00% in May after the Reserve Bank kept them unchanged last month.
The Bank tries to keep inflation between its comfort level of 3-6% and projected that the average would be 4.8% this year, below the previous forecast of 5.5%. An average of 5.3% is expected by 2020.
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