Some of the paving needed to be dug up and asphalt re-laid, NZ Transport Agency Waka Kotahi (NZTA) said.
Work by Downer would start at the intersection of Beach St and George St.
It would then move along George St, the town’s main street, towards the Wickliffe Tce intersection.
NZTA Otago and Southland senior network manager Michael Tannock said the work needed to be completed ahead of the cruise ship season, due to begin in October.
It would be carried out from 7pm to 6am, Sunday to Thursday. The agency was working with Port Otago to minimise disruption in the area, he said.
Mr Tannock said it was best to do the work at night because the area was busy during the day and people needed to be kept safe around deeply excavated sites.
Stop-go traffic management and speed restrictions would be in place during the works and there might also be temporary speed limits during the day if road services were uneven.
"As we prepare for the upcoming asphalt renewal, there will be some works taking place in August on the footpath kerb and channel at Port Otago, as well as work in both lanes at the south end of George St", Mr Tannock said.
It is expected the intersection of Beach St and George St will be closed for up to five nights.
The next two stages of work are expected to run from September 8-19.
Bus routes could be affected by detours.
Mr Tannock said the crews would look to minimise their impact on nearby residents and businesses, as well as road users, but some noise, disruption to traffic and restricted driveway access was inevitable.
Footpaths within the site would be open for use, but people needed to stay away from any areas of excavated pavement.
