The ideal window for a Hyderabad family is October through March, when Phu Quoc's dry season sets in and Ho Chi Minh City stays warm without the peak humidity of summer.
For Telangana families working around school terms and office leaves, the Dussehra break in October, Diwali in late October or November, and the Christmas–New Year school holidays in December are the most practical windows. October marks the start of Phu Quoc's dry season, though early-month rain showers are still possible, so late October onward is safer for beach plans.
November is a genuine sweet spot — the sea turns calm, skies clear up, and hotel rates haven't yet hit their December peak, making it ideal if you're travelling around Diwali holidays. December brings the most reliable weather of the year, with minimal rainfall and comfortable temperatures around 27–30°C, but it's also peak season, so book flights and Phu Quoc resorts well in advance if you're planning around the winter school break.