Dengue cases have dropped by about 70 per cent since the peak of 1,792 reported in a single week in July.
A total of 532 new cases were reported last week, said Minister of State for Sustainability and the Environment Desmond Tan in a Facebook post on Monday night.
But Singapore is not "out of the woods" yet, as last week's case count is "still a very high figure", added Mr Tan.
He said that the National Environment Agency's (NEA) Gravitrap surveillance system has also detected a rise in the Aedes aegypti mosquito population for five consecutive weeks now, and that the rate of decline in weekly dengue cases has slowed over the last four weeks.
To avoid a second spike in weekly dengue numbers before the end of this year, cases would have to be brought down by more than half, said Mr Tan, who is also Minister of State for Home Affairs.
He warned that next year might witness another bad outbreak, if the new year starts with "a high baseline of dengue cases".
This year's dengue outbreak has been the worst in Singapore's history, with 31,341 cases reported in the first 41 weeks, surpassing the previous high of 22,170 reported for the whole of 2013.
As at Monday, two of five superclusters, with 300 or more people infected, were still active.
One in the River Valley and Killiney area has had 381 cases since the cluster started on June 1, while the other cluster in Aljunied and Geylang has had 324 cases since it started on May 19.
Prior to this, only one supercluster had been formed between 2013 and last year. That cluster in Choa Chu Kang, with a total of 534 people infected, lasted two months - from June 25 to Aug 25, in 2014.
Altogether, 176 clusters were still active across the island as at Monday.
The Ministry of Health said that as at Sept 5, it was notified of 21 dengue deaths for this year, with the patients ranging between 25 and 92 years old.
The vast majority of those who died - 18 - worked or lived in active dengue clusters.
NEA has continued to work with town councils and their partners to step up dengue prevention and control measures in housing estates.
Their efforts to control the mosquito population include cleaning drains and removing discarded receptacles to prevent the accumulation of stagnant water.
Mr Tan urged residents, especially those living in dengue cluster areas, to remain vigilant.
"Spray insecticide in dark corners around the house, apply insect repellent regularly and wear long-sleeve tops and long pants," he said, adding that all should help ensure that their homes and immediate surroundings are free from stagnant water.
