South Australia has recorded three more deaths from COVID-19, taking the total since the start of the pandemic to 67.
The number of new cases dropped to 2,193, compared to 3,023 cases on Friday.
"[This is] a very significant fall and certainly our lowest number for a very long period of time," Premier Steven Marshall said.
The number of hospitalisations has also fallen, by 23 to 275, but ICU numbers have increased slightly, to 37, and seven people remain on ventilators.
The government said Friday's hot weather caused delays to PCR testing and may have contributed to the lower number of cases being reported.
"The numbers do jump around a little bit and of course we had hot conditions yesterday and so there was a delay in PCR testing," Mr Marshall said.
A total of 12,565 PCR tests were administered and 5,375 rapid antigen test (RAT) kits were distributed.
Mr Marshall said the RAT collection site for close contacts in Adelaide's southern parklands would be scaled down, but new collection sites were opening.
"We did have a massive delivery of RAT kits into South Australia yesterday — 722,000," he said.
"We certainly are not having supply problems there."
The Premier said the state was also doing "extraordinarily well" in terms of boosters.
"The mandated booster is already in place for aged care, hospital settings, forensic science and the disability sector.
"I think it's fair to say that we will look at other settings as well. Where we've mandated two doses, we're very likely to move to mandating three doses."
City council support package for struggling businesses
The government reiterated its request that businesses encourage a gradual shift away from working from home this week.
The Premier said the government would encourage "the gradual return for office work" from Thursday.
"We're very grateful for the people that could work from home who did work from home – this really slowed down the progression of the disease," he said.
"We'll very gently and prudently increase that now, starting with 25 per cent office capacity from the 27th onwards and then we'll gradually ease that up."
Business SA chief executive Martin Haese has welcomed the plan — but said it does not go far enough, and that capacity limits on venues were still too tight.
"We'd like to see that 25 per cent moved to 50 per cent," he said.
Mr Marshall said that it was the government's intention to consider other restrictions and "what the likely easing of those would do in terms of case numbers and in particular, hospitalisation".
The Premier praised an Adelaide City Council support package for CBD businesses, which have been battling "extraordinarily tough" trading conditions.
At a special meeting on Friday night, the council unanimously voted to adopt more than 20 measures as part of a plan dubbed Reignite Adelaide 2.0.
The measures include free on-street parking in "key precincts", cash grants for small businesses that have been hit the hardest, and a $250,000 advertising campaign to promote the city and its hotels.
"We will continue to focus on the practical things we can do to get people returning to the city and supporting our businesses."
Meanwhile, organisers of a music festival in the state's Mid North region have said that attendees will be required to produce a negative RAT as a condition of entry.
About 800 people are expected to attend the Copper and Stone Music Fest in Burra and organisers have been procuring enough tests.
Organiser John Simpson said the policy means that it will take about 15 minutes longer to enter the festival, but that it would lead to a safer experience.
"This also means that we can now allow non-vaccinated people to attend — it just becomes more inclusive for people," he said.
