Chief Medical Officer Sir Harry Burns said the norovirus "season" had been officially declared on October 29 – around five weeks earlier than last year.
Sir Harry said: "This may be indicative of a higher than normal level of norovirus circulating this winter."
The bug's symptoms of diarrhoea and nausea can be serious in young children and elderly people because of the risk of dehydration.
While there is no clear way of measuring how many cases have been detected, given that sufferers are advised to stay away from GP surgeries during an infection, figures show half of all health boards in Scotland have had hospital wards closed due to norovirus this week. Sixteen hospitals across the country had 24 wards closed on Monday, with 208 patients suffering from the sickness and diarrhoea bug. A total of 90 NHS staff are recorded as being infected this week.
Patients have been worst affected in NHS Lothian area, with 58 people suffering from the bug while in hospital. Nineteen staff have contracted norovirus with four wards closed across three hospitals.
Three hospitals have been hit by the bug in the Glasgow area, with 33 patients and 12 staff affected.
NHS Borders reported 27 patients and 10 staff with the infection.
Sir Harry urged people to take precautions to stop the spread.
He said: "Norovirus, or the winter vomiting bug, spreads quickly where people are living or working in close proximity such as schools, hospitals, care homes, offices and hotels.
"The virus is highly infectious and unpleasant, but fortunately most people make a full recovery."
Those who catch the bug are advised to drink plenty of non-alcoholic, non-milky drinks and also take oral rehydration solutions. They should also ensure their hands are clean to prevent the infection from spreading and they should not prepare food for others, particularly babies and the elderly.
The first sign of norovirus is usually a sudden sick feeling followed by forceful vomiting and watery diarrhoea. Others include suffering high temperatures, headaches, stomach cramps and aching limbs. Most occur within one to two days of being infected, but can occur sooner.
Chief Nursing Officer Ros Moore said: "The symptoms of norovirus usually clear up in a couple of days and are generally not serious. However, diarrhoea can be serious in babies and the elderly because of the risk of dehydration. If diarrhoea is persistent or there are other symptoms such as bleeding, you should contact your GP."
She added: "There are simple steps everyone can take to prevent the spread of the virus, including washing your hands properly. If you have vomiting or diarrhoea you should not go to school or work until 48 hours after your symptoms have ended."
Hugh Pennington, emeritus professor of bacteriology at Aberdeen University, said: "The longer the virus is busy the more cases there may be, but there might be good news too – it might fizzle out earlier than normal."
In April, Scottish Government figures revealed the norovirus had been responsible for more than 1000 ward closures since 2009.