The Beast from the East means delays on the A47 until May at least.
Diversions are in place at the Saddlebow Interchange, on the southern outskirts of King's Lynn, while repairs are carried out to two bridges.
The crossings were damaged when they were hit by a digger which was being carried on the back of a lorry.
Officials expected the work, which includes some overnight and weekend closures of the Lynn southern bypass between the Pullover and Hardwick roundabouts, would be completed by early April.
But Highways England spokesman Jack Tapp said: 'The guys were working at the start of the week but they haven't been as the weather's deteriorated.
'The latest completion date is due to be the beginning of May. There was an unexpected crack found on the west bridge which needs further repair work.'
The delay means work will be carried out over the Easter weekend.
Comments: Our rules
We want our comments to be a lively and valuable part of our community - a place where readers can debate and engage with the most important local issues. The ability to comment on our stories is a privilege, not a right, however, and that privilege may be withdrawn if it is abused or misused.
Please report any comments that break our rules.
Read the rules here