Hoang Vu of Hanoi said he paid VND3.8 million (US$154) for a round-trip night flight to Da Nang in July, but now the fare has dropped to just VND2 million.
"The prices are cheap, but summer is over, and families with young children cannot travel at this time, especially with the current weather conditions."
He himself prefers traveling to Da Nang in summer despite the higher prices, he added.
The lowest round-trip fare between Hanoi and Phu Quoc on weekends in October is around VND2.9 million.
It had cost up to VND5 million in summer, and over VND7 million during the Reunification Day (April 30) holidays.
On the Hanoi-Nha Trang route, fares in October are VND2.8 million as against VND4 million in June.
Fares from HCMC to Da Nang and Phu Quoc have also fallen sharply.
Bui Thanh Tu, marketing director at Hanoi travel firm Best Price, said domestic airfares have dropped by 25% since September and are likely to remain low until the end of the year since it is the low season for travel.
Those benefiting from the lower fares are mostly business travelers, he added.
Data from online travel platform Traveloka shows that while the number of bookings and searches for airfares by Vietnamese customers steadily increased between May and August, interest dropped sharply in September.
Searches fell by 38% from August, and actual ticket purchases by 50%.
Tran Quoc Hung, head of product development at Mustgo, an online booking platform with over 2,000 hotel partners in Vietnam, said room occupancy rates have also dropped.
Major tourist destinations across the country report an average of just 20-30% occupancy, a 40 percentage point decline from summer. The majority of visitors to destinations like Phu Quoc and Da Nang are foreigners.
Bad weather in the northern and central parts of the country is a major factor deterring travelers, Hung said.
Five more storms and tropical depressions are expected to form over the East Sea, also known as the South China Sea, in the last quarter of the year, with two or three potentially impacting Vietnam, according to the Institute of Hydrology, Meteorology and Climate Change.