The 5th of May in the lunar calendar is the Double Fifth Festival, also known as the Dragon Boat Festival or the day to eradicate insects and worms. In folklore, it is said that the 5th of May in the lunar calendar is the most feared day.
This is not a baseless superstition, as it holds a certain connection to reality. The ancient Vietnamese, heavily reliant on agriculture, paid close attention to natural phenomena as they believed these events were linked to their harvests. The 5th of May holds a special significance in the water-rice civilization.
1. Fear of the 5th of May: A Time of Intense Heat and Its Impact on Crops
The 5th of May in the lunar calendar marks the midpoint between the winter-spring rice crop and the upcoming summer-autumn rice crop. However, it is also the time when the scorching heat begins to intensify.
Being in the summer season, the climate undergoes significant changes. ‘Doan’ means the beginning, and ‘Ngo’ refers to noon. The intense heat during this period signifies that the entire summer will be unbearably hot, impacting crop production. The excessive heat can cause rice to wither, affecting the harvest and potentially leading to a year of famine.

Moreover, the excessive yang energy disrupts the balance between yin and yang, increasing the likelihood of adverse events: from extreme weather conditions and disease outbreaks to heightened stress and anxiety in people. The intense heat negatively affects health, leading to an increased risk of heat stroke and sudden dizziness.
In the past, without a thorough understanding of modern medicine, people often attributed these health issues to evil or toxic spirits, believing that the overwhelming yang energy made this day particularly fierce and uncontrollable, deeming it a “toxic day” in the year, warranting caution in all endeavors.
2. The 5th of May: A Time of Pest and Disease Outbreaks, Causing Fear and Anxiety
During the 5th lunar month, the typically hot and humid weather creates favorable conditions for the proliferation of pests and insects, which can lead to disease outbreaks.
In agriculture, this insect proliferation can result in crop destruction. For humans, disease outbreaks can lead to severe illnesses, particularly gastrointestinal issues.
In the past, when people relied solely on nature and lacked access to chemical pesticides or medications, combating disease outbreaks was incredibly challenging.
Hence, the fear associated with the 5th of May in the lunar calendar stems from the concern that such outbreaks might occur and prove insurmountable.
In reality, as the 5th of May marks the beginning of the hot season, people might not have had time to adapt to the changing weather. Additionally, the combination of intense heat and high humidity creates an ideal environment for the proliferation of bacteria, viruses, and insects, impacting both crop production and human health.

3. The 5th of May: A “Double Five” Day, Considered Unlucky and Feared for Its Potential Negative Impact
In spiritual beliefs, the 5th of May in the lunar calendar is also feared due to the notion that days when the date and month are the same are considered inauspicious. This phenomenon is referred to as “Nguyet Kien Ngu” in Vietnamese folklore.
According to the I Ching and the five elements, the number 5 represents the center and powerful movement. When two 5s coincide, the energy becomes chaotic and uncontrollable, leading to instability. This instability can also give rise to strong evil forces that influence people.
Thus, the fear associated with the 5th of May stems from the belief that this instability could affect one’s temperament, health, and relationships.
Additionally, it was considered unlucky for a mother to give birth on the 5th of May, as it was believed that the child’s future would be unfavorable.
4. Scientific Basis for the Fear of the 5th of May in the Lunar Calendar
According to the solar calendar, the 5th of May in the lunar calendar usually falls in June or July, which coincides with the hottest period of the year, just before the peak of the hot season.
During this time, people are concerned about the negative impact of the weather on their daily lives and health. As it is also the time for preparing the new rice crop, excessive heat can be detrimental to the harvest, affecting prosperity and wealth.
On the 5th of May in the lunar calendar, it is essential to be cautious about the following:
- Increased risk of heat stroke and sunstroke, especially for the elderly, children, and those with pre-existing health conditions.
- Food spoilage and potential food poisoning if not properly stored.
- Lowered immunity, making individuals more susceptible to viruses and bacteria.
Thus, aside from spiritual beliefs, the fear associated with the 5th of May in the lunar calendar is rooted in weather conditions, natural phenomena, and agricultural practices.
5. Taboos and Superstitions Associated with the 5th of May
- As the 5th of May is considered an unlucky and feared day, there are several taboos observed by the Vietnamese, including:
- Avoid holding weddings, engagements, or other important ceremonies.
- Do not start construction or break ground for a new house.
- Refrain from opening a new business or shop.
- Do not travel or embark on new ventures.
It is believed that engaging in these activities on this day could bring bad luck, obstacles, or even misfortune.
6. Folk Customs to Ward Off Bad Luck on the 5th of May
Due to the aforementioned fears, the 5th of May has become a festival day in Vietnamese culture. It serves as a reminder to be grateful for favorable natural conditions for crop production and to take precautions against the potential harms associated with this day.
As a result, the 5th of May, or the Dragon Boat Festival, has evolved unique customs to ward off evil, cleanse the body, dispel bad luck, and exorcise evil spirits. These customs include:
- Consuming fermented sticky rice wine, ash cake, and duck meat to eradicate bacteria, aid digestion, and cool the body during hot weather.
- Hanging mugwort, cactus, garlic, lemongrass, and five-color strings at the door to ward off evil and drive away insects and toxic spirits.
- Taking a bath with fragrant leaves such as basil, grapefruit, lemongrass, or mugwort, a traditional form of “steam bath” to relax and detoxify the body.
- Shaking the tree: One person climbs a tree while another shakes its trunk to predict the amount of fruit it will bear in the coming year, ensuring a prosperous harvest.
- Avoiding going out and painting fingernails red to ward off evil spirits.
The saying, “fear the 5th of May,” reflects the ancient people’s concerns about natural phenomena. These beliefs are still prevalent in folklore today, not merely as spiritual concepts but also as practices rooted in weather and natural phenomena. Therefore, it is advisable to follow the ancient wisdom of maintaining a healthy diet, preventing summer diseases, and avoiding going out during noon to stay safe.
Reference for contemplation
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