According to the Lunar Calendar, the sixth lunar month of 2025 is a leap month, so the number of lunar days will be 19 days longer than the solar calendar. This means that from the first day of the Lunar New Year At Ty (January 29, 2025) to the first day of the Lunar New Year Binh Ngo (February 17, 2026) will be 384 days long.
Similarly, 2028 is also a leap year in the Lunar calendar and has an actual number of days longer than 365 days.
Regarding this, researcher Dang Vu Tuan Son, President of the Vietnam Astronomy and Cosmology Association (VACA), said that the Lunar calendar is based on the phase cycle of the Moon - each phase cycle is called a lunar week, or as we commonly call it, a lunar month. The average length of a lunar month is 29.53 days, and therefore the length of 12 months is only 354 or 355 days.
The expert explained: "Every 3 years, the difference between the Lunar and Solar calendar systems will increase by 1 month, which causes inconvenience to the daily schedules of places that still use the Lunar calendar like Vietnam, and at the same time, the dates in the Lunar calendar no longer reflect the correct weather cycle."
For that reason, every 3 years we have an extra month added to the Lunar calendar. Such years have 13 months and are called leap years. The upcoming year of At Ty is such a year. Because there are 13 months, instead of 354 days, the year of At Ty lasts 384 days.
Experts also confirmed that this will not have too much impact on daily life, agriculture, weather or climate in 2025.
"The lunar calendar is not considered a suitable tool for weather prediction, so the addition of a month to the lunar calendar does not reflect weather fluctuations. For people's lives, those living in cities or working according to the general administrative calendar do not experience any impact.
As for agricultural activities, celebrating Tet late will require farmers to adjust some times, for example, rice planting usually takes place from January to early February of the solar calendar, so the time of Tet holiday will determine the difference in the time of sowing and planting rice, however, this difference does not have a significant impact on the results when harvesting," said Mr. Dang Vu Tuan Son.
From another perspective, the most obvious impact of a 13-month lunar year is that children have to wait longer for Tet holiday and, conversely, adults "breathe a sigh of relief" because they can do a lot of things before having to empty their wallets for year-end shopping.
2025 is also a special year because December only has 29 days, without "30th night". It will not be until 2033 that people will experience the 30th day of Tet again.
