Snow delayed the reopening of a key Dunedin intersection by a day and it was unclear on Tuesday evening if the delay might need to be extended.

Part of Strathallan St was closed from May 18 while the approach to the intersection with Portsmouth Dr and Wharf St was reconfigured.

It had been due to reopen on Tuesday, but contractors were busy dealing with snow, which caused dicey driving conditions in the city.

By 11am, the Dunedin City Council had pushed out the expected time of Strathallan St reopening to Wednesday.

Later on Tuesday, the council warned motorists to take care on the roads over the next few days as frosty conditions had been forecast.

Contractors would be out overnight, monitoring conditions and sweeping snow, as needed.

Reconfiguration of the intersection of Strathallan St, Portsmouth Dr and Wharf St is expected to improve the harbour arterial route, which is intended to operate as a bypass in the central city, particularly for heavy vehicles.

A second left-turn lane from Strathallan St into Wharf St is replacing a right-turn lane into Portsmouth Dr.

The change is aimed at improving traffic flow into the central city from the south.

The council said it would create more capacity and improve traffic flow in Strathallan St.