Ho Chi Minh City has a tropical climate with two distinct seasons: dry (November to April) and wet (May to October). The temperature stays around 27–35°C year-round with high humidity; the dry season is not dramatically cooler than the wet but the absence of daily downpours makes it more comfortable for sightseeing.
Dry season (November to April) is the best time to visit. December, January, and February are the most pleasant months — slightly less punishing humidity, clear skies, and the Tết preparations building toward the new year.
Wet season (May to October) brings daily afternoon and evening downpours, usually intense but short. The streets flood briefly and then drain. Vietnamese take no notice of the rain and it does not close anything down; the heat before the rain breaks is more uncomfortable than the rain itself. Prices and crowds are lower in the wet season.
Tết (Vietnamese New Year) — falling in late January or February depending on the lunar calendar — is spectacular and complicated. The city decorates lavishly and the streets fill with flower sellers and fireworks. But many restaurants and shops close for several days while families travel home, so planning around the holiday is important. Book accommodation well in advance.
Other festivals worth timing a visit around: the Jade Emperor Pagoda Festival in January or February; the Lantern Festival (Tết Nguyên Tiêu) fifteen days after Tết; and the Lăng Ông festival at the Tomb of Lê Văn Duyệt in the eighth lunar month (usually September or October).