The opening date for the Queensferry Crossing has been pushed back to the summer because of adverse weather.
Keith Brown, the Economy Secretary, said high winds were to blame for the delay to the £1.3bn project, which will now miss its contractual deadline.
The new Fife to Edinburgh crossing was supposed to open to traffic in December last year, before it was deferred to May.
Mr Brown said on Wednesday it would now not be ready before July, with the possibility that it could be as late as August.
Speaking at the rural economy and connectivity committee, he said wind had prevented the removal of cranes and work on cable stays.
He added rain had stymied activities like waterproofing the road.
Mr Brown told MSPs that contractors are “now advising that the opening to traffic date is more likely to be between mid-July and the end of August”.
He added: “While its clearly very disappointing the new bridge won’t be ready ahead of the contractual completion date, I believe it is important to take the time to make sure the bridge is built in the safest possible circumstances to the highest possible standards.”
Scottish ministers were forced into admitting the existence of a delay on Tuesday through a question from Perthshire-based MSP Murdo Fraser.
Holyrood was told that windy weather had hampered the removal of cranes on the 1.7-mile link.
The Scottish Government said crane removal work that would reasonably be expected to be completed in 15 days, was taking more than four times as long.
The fresh delay means contractors Forth Crossing Bridge Constructors will not finish the job before the contractual completion date of June 2017. That means Transport Scotland could claim for damages.
Mr Brown said the project is on a fixed price, which he said was nearly a quarter of a billion of pounds under budget, so the delay will be at no cost to the taxpayer.
Asked whether he could promise the bridge will be open by the end of August, Mr Brown said: “I can’t give 100% guarantees.”
Liam Kerr, for the Scottish Conservatives, said the delay is a “huge blow” to commuters who cross the Firth of the Forth.
“The SNP assured us that this project would be delivered on time, but these promises have proven to be worthless as, once again, we see the completion date slipping.
“It is simply unacceptable, and the economy secretary needs to explain why this delay has occurred and what the Scottish Government are going to do to ensure the new timescale is kept to.”
He added Mr Brown had questions to answer over when he knew about the fresh delay.
The three-tower bridge sits alongside the Forth Road Bridge, which will continue to be used by buses, taxis, cyclists and pedestrians once the new crossing is open.