Hanoi is one of the few places in Vietnam with genuine seasonal variety — unlike the south, which runs on a simpler wet-dry cycle, the north actually gets a real winter. That makes timing more nuanced, but also means there's a clear window most travelers land in without meaning to.
October to April: the comfortable season
This stretch covers Hanoi's cooler, drier months and is generally considered the best time for sightseeing — walking the Old Quarter, exploring Hoan Kiem Lake, and day-tripping out to Ha Long Bay all work well without the summer humidity working against you. Within this window, September to November tends to bring the most reliably pleasant weather, with clearer skies and comfortable temperatures before winter's chill sets in.
December to February: genuinely cold winters
Hanoi's winter surprises a lot of first-time visitors — temperatures can drop into the low teens Celsius, and gray, misty days are common. It's still a good season for café culture, museums, and food-focused itineraries, just pack layers rather than assuming Vietnam means year-round heat.
Tet (Lunar New Year): plan around it, not through it
Tet usually falls in late January or February and is Vietnam's most important holiday. Many shops, restaurants, and some attractions close for several days, transport books out well ahead, and accommodation prices rise. It's a genuinely fascinating time to be in Hanoi culturally, but not ideal if you're relying on a fully operational city with predictable hours — check the specific dates for your travel year before booking around this period.
May to September: hot, humid, and rainy
Summer brings Hanoi's highest temperatures and humidity, along with its wettest months — typically July and August see the heaviest rainfall. It's also the cheapest and least crowded time to visit if you don't mind the heat and the occasional sudden downpour.
Practical notes
- Pack layers for winter (December–February) — a light jacket or sweater is genuinely necessary, not optional
- A light rain jacket or umbrella is worth carrying June–September
- Check the specific Tet dates for your travel year, since they shift on the lunar calendar
- Comfortable walking shoes matter more than season — the Old Quarter is best explored on foot
The short version
September to November is the standout window for weather. December through February is cooler than most expect, so pack accordingly. Avoid or specifically plan around Tet depending on what you want from the trip, and treat summer as the budget-friendly, humid trade-off season.