Bangor is due to go into lockdown later with discussions continuing on the situation in other parts of Gwynedd due to the number of Covid-19 cases.
Eight wards in the city will have tighter rules imposed from 18:00 BST.
They will be similar to other areas in Wales in lockdown, meaning people cannot enter or leave without good reason, such as going to work.
“There’s no promise that other parts of the county won’t face lockdown,” said Gwynedd council leader Dyfrig Siencyn.
The Welsh Government said “further discussions will be held with the local authority and the incident management team about the wider situation in Gwynedd on Saturday”.
Bangor had seen a significant cluster of cases and the incident rate stands at about 400 cases per 100,000 people.
It said cases appeared to be closely associated with young people and the student population.
In north Wales, the counties of Conwy, Denbighshire, Flintshire and Wrexham are already in lockdown.
Bangor’s restrictions will affect eight wards in the city: Garth, Hirael, Menai, Deiniol, Marchog, Glyder, Hendre and Dewi.
Seventeen of Wales’ 22 counties are now facing local lockdown restrictions at least in part, affecting more than two million people.
Mr Siencyn told BBC Radio Cymru’s Post Cyntaf programme there were signs the number of cases was increasing in Arfon and Dwyfor.
“I don’t think [we’ll see lockdowns] for the entire county at the moment,” he said.
“But, of course, things can change quickly with this virus, and things could change over the next few days.
“We’ll be keeping an eye on the number of cases every day, and there’s no promise that other parts of the county won’t face lockdown.”
Jules Lee, who runs a tattoo shop in Bangor, said it was “very difficult to get people to follow the rules” on social distancing.
“We’ve got massive signs saying one person at a time, and the amount of time that we’ll have to tell them ‘I’m sorry’ [because] they come three or four people at the same time.
“It’s really awkward. It’s difficult to get people to comply,” she told BBC Radio Wales Breakfast.