The rainy weather may have caused the peak flu season to last a little longer than usual, say doctors.
The season usually runs from September to December, but patients are still turning up at clinics.
Dr Lim Chien Wei, the cluster head of Healthway Medical Group, said that the recent rainy, cool weather could have allowed viruses to survive longer.
Polyclinics saw an average of 3,158 patients with acute respiratory infections every day during the first week of this month, according to the Health Ministry.
This was up from the 2,836 patients who were seen in the same period last year.
The figure had not crossed the 3,000 mark since October last year.
Dr Michael Wong, a family physician at Raffles Medical, said that he has seen an increase in the number of patients with symptoms such as cough and nasal congestion in recent weeks, although he did not give numbers.
He added that while a person cannot literally "catch a chill" and fall ill because of cold weather, the chill could be a factor in allowing viruses to spread.
"Staying indoors increases the proximity between people," Dr Wong said. "With the increased recycling of air indoors or in an air-conditioned environment, respiratory viruses have a higher incidence of spreading."
Dr Lim noted: "When adults and children start going back to work and school after the holidays, the spread of viruses can become more prevalent."
Singapore has two peak flu seasons a year, one from April to June, and the one winding down now.
Dr Lim said that he sees about 20 per cent to 30 per cent more patients with colds or the flu during these periods.
While influenza and the common cold are caused by viruses, flu symptoms can be more severe and result in serious health problems such as pneumonia.
"Antibiotics are of no use against cold viruses, and are often not prescribed unless there is also a bacterial infection," said Dr Wong.
Instead, treatment is typically aimed at helping to alleviate the symptoms. Those infected should drink plenty of fluids and practice proper hygiene to avoid spreading the illness to others.