Based on infection rate trends and the government's roadmap steps, public health intelligence teams have predicted that Portsmouth and the surrounding areas will see a rise in coronavirus cases between May and June.
It is anticipated this wave, which is also expected to hit the rest of the country, will not be as severe as the one experienced at the end of 2020 and will not see the NHS 'overwhelmed' with cases, mainly due to the success of the vaccination programme.
But Helen Atkinson, the city's public health director, warned that the severity of the surge depended on the behaviour of residents.
She said: 'Our modelling shows a surge in cases expected by the end of May taking into account some of the easing of restrictions.
'As it stands we will still be meeting these dates - such as the rule of six on March 29 - but people must not push rules. '
She added that some people might get 'complacent' having been vaccinated.
'The vaccination programme has been such a success and it's great that so many people have already been vaccinated,' she said.
'But we have got a lot of people who think that because they've had their vaccine it's over. But it doesn't mean that you won't get coronavirus - no vaccine is 100 per cent effective.
'The reality is Covid is not going anywhere, we will have to learn to live with it in the same way we have to live with flu. And like flu I think we will see people having booster vaccines every year to deal with Covid variations.'
According to the latest data 58 per 100,000 people in Portsmouth currently have Covid, which is down from 85.2 people at the end of February.
Council leader Councillor Gerald Vernon-Jackson said: 'Lockdown has been horrible to do but we don't want to blow all the progress we have made.
'Don't forget if you get Covid you might not be affected but you could pass it on to your granny.
'Portsmouth has behaved very well over the last year, we just have to keep that going.'