While the lives of many people have been affected by recent cold snap, business has picked up for many taxi drivers and traders in winter garment and heaters.
Le Thanh Hai, deputy director of the National Center for Hydro-Meteorological Forecasting, said the north of the country was suffering its coldest spell since 2008.
On Wednesday, hundreds of schools closed as temperatures in most of northern Vietnam fell below 10 degrees Celsius.
In mountainous areas, including the popular tourist site of Sa Pa, the mercury slipped below zero Celsius, preventing tourists from leaving their hotels. The cold snap started on January 3, and is forecast to last at least until January 21.
Garment shops along the streets of Hanoi are unusually crowded. A shop assistant in Bach Mai Street said the number of customers has doubled, even tripled compared to several months ago. Prices have increased by as much as 20-30 percent.
"Coats and sweaters are selling like hot cakes. Many products sell out just a day after being shown in the shop," she said.
Vietnamese brands like Made-in Vietnam, Nino Max, and Canifa are attracting most of the customers.
A saleswoman at a Made-in Vietnam outlet in Chua Boc Street said her shop has sold nearly 100 coats in the past few days. Big coats priced at VND500,000- 600,000 (US$23.8-28.6) are the best sellers, she said.
Woolen hats, scarves, and gloves are also selling fast. At a shop on Hang Dao Street, Nguyen Thi Hong was busy with a group of young customers.
"I plan to employ one more shop assistant. The two I have now cannot manage the increasing number of customers, so I have to pitch in sometimes," she said, as customers jostled to try on clothes and made way for the cash registers.
Nguyen Thi Thu, owner of a shop selling bedding products on Phung Khac Khoan Street, said she'd sold 15-20 sets every day, about 30 percent more than normal.
Meanwhile, shops selling electric heaters are facing a supply shortage following big sales over the past few days. Nguyen Quoc Trung, a customer at a shop on Phung Hung Street, said he purchased a heater made in China a day earlier, but there was something wrong with it, so he'd brought it back to change it for another. "However, I could not change it... I have to wait until the shop receives new batches of the goods."
Many people, especially white collar workers and parents of small chidren, are choosing to travel by taxi instead of motorbikes because of the cold.
Dinh Thu Thao, a garment trader on Vuong Thua Vu Street, said she could not call a taxi on the phone these days because the lines were always busy.
She has to stand on the street and flag one down to take her sixyear-old daughter to school every day, Thao said.
Nguyen Van Bao, a taxi driver from Nam Dinh Province, said on the cold days, the number of customers he picks up from primary schools in Dong Da District alone is equal to the calls he received from all corners of the city a few weeks ago.
"During the cold snap, there are days I've earned more than VND1 million. Usually, I would get VND200,000-300,000 at the most," he said.
"If the cold snap prolongs, I will have a big Tết," Bao said.