According to the timekeeping method in winter that Chinese people have used since ancient times, winter is divided into 9 chains of 9 days (totaling 81 days), calculated from the start of the Dong Chi period.
This division is recorded in an ancient epitaph, with the first 2 sentences: "The first 9 days, the second 9 days, don't take your hands out of your pocket; The third 9 days, the fourth 9 days, you can walk on ice".
Accordingly, the 9-day streak of Tuesday and Wednesday is the coldest in winter. Ancient Chinese people called the 3-day streak "sanjiu" (tam cuu), which means from the 19th to the 27th day from the beginning of the Dong Chi period. This time is the coldest according to folk beliefs, Visit Beijing reported.
This winter, the start of the Winter Chi in this winter is December 21, 2025. From that day on, today, January 8th, is the beginning of the "third 9-day streak", which is the beginning of the 18-day coldest streak in winter (the third and fourth 9-day streak).
That is considered according to traditional concepts combined with climate observation.
Correspondingly, according to weather forecast models, the North and Hanoi begin to enter the coldest days of winter this year.
The National Center for Hydro-Meteorological Forecasting forecasts that the cold air wave has affected the South Central Coast region. In the North and Thanh Hoa, it is very cold, with severe cold in some mountainous areas. The area from Nghe An to Da Nang City is cold, with severe cold in some places.
The lowest temperature in this cold air wave in the Northern Delta and Thanh Hoa is commonly 8-11 degrees Celsius, mountainous and midland areas of the Northern Delta 6-9 degrees Celsius, and high mountainous areas in some places below 3 degrees Celsius.
Nghe An and Ha Tinh are commonly 11-13 degrees C. The area from Quang Tri to Da Nang City is commonly 14-17 degrees C.
From January 9-11, the Northern and North Central regions will not have rain at night, early morning fog and light fog will be scattered, sunny during the day; from January 13 there will be light rain in some places. It will be cold, with severe cold in some places; especially the mountainous and midland areas of the Northern region from the night of January 9-12 will be severely cold, with severe cold in some places. Northern mountainous areas should be wary of frost and frost.
The area from Quang Tri to Da Nang City and the east of provinces from Quang Ngai to Gia Lai: showers in some places; especially on January 11, there will be rain, scattered showers and thunderstorms in some places. The North will be cold. Other areas will have showers and thunderstorms in some places at night, sunny during the day.
Hanoi weather is very cold, the lowest temperature in this cold air wave is commonly 8-11 degrees Celsius. The temperature is much lower than the cold spells in December 2025, when the temperature was about 16-17 degrees Celsius.
On the morning of January 8, the lowest temperature in Hanoi measured in Ha Dong was 9.2 degrees Celsius. Cloudy, no rain.
From January 9-11, it will be less cloudy, no rain. Hanoi's temperature will remain at the lowest level of 9-10 degrees Celsius, the highest from 21-23 degrees Celsius. It will be very cold.
From November 13th, Hanoi's weather will gradually warm up, but the temperature will remain low. The lowest temperature ranges from 12-17 degrees Celsius, the highest from 23-25 degrees Celsius. It will be very cold.
People and tourists planning to travel to Hanoi or the North during this time should pay attention to bringing warm clothes and heat-retaining items. Avoid going out at night, near dawn when the temperature drops to the lowest level to ensure health.
