The Ministry of Water Resources and Meteorology has issued a second warning that temperatures in some provinces could drop as low as 13 degrees Celsius this week.
The previous announcement last week predicted temperatures of 17 or 18 degrees Celsius.
The Dangrek Mountain area on the border with Thailand will be worst hit by the cold snap, which is caused by a high pressure system coming from China.
Temperatures of about 15 degrees Celsius are expected until at least Friday in Stung Treng, Ratanakkiri, Mondulkiri, Preah Vihear, Oddar Meanchey and Pailin provinces.
Pursat, Battambang, Siem Reap, Banteay Meanchey and Koh Kong provinces will meanwhile see temperatures of between 17 and 18 degrees Celsius.
“In other provinces, the temperature will be about 19 to 20 degree Celsius, except in Kep, Kampot and Preah Sihanouk, which will not be so cold,” the statement said.
“The public and authorities should be careful and prepare for the cold weather, especially soldiers stationed on the border along the Dangrek Mountains.”
The ministry earlier said that cold bouts of weather would begin in the middle of December and last longer and be cooler than previous years.
Chhim Sovanth, a tourist police officer at Preah Vihear temple, which is in the Dangrek Mountain area, yesterday said the weather had been colder than usual since the start of the month.
“Over the past two days, the temperature has dropped to nine degrees Celsius at night, which is very cold,” he said.
Mr Sovanth said that normally the temperature is between 22 and 23 degrees Celsius in the day at this time of year. “I have lived here for about seven years, but when the weather is cold like this it makes it difficult to stay,” said Mr Sovanth. “We need more coats and blankets to protect us from the cold.”