Too lazy to read it all. Give me the short version
Short on time? Here’s the answer to “When should I visit Ha Long Bay?”:
March–April or October–November. Dry, beautiful, perfect.
But "when" is only half the answer. Keep reading. There’s a trap.
Don’t expect to be alone when you visit Halong Bay | Mr Linh's AdventuresA trap called Ha Long Bay
Ha Long Bay was crowned the world’s most beautiful bay by… mass tourism operators. A Google search for “most beautiful bay in the world” points to the Club of the Most Beautiful Bays in the World. Ha Long is on the list, of course. And always with the same shot: vertical karsts, emerald water, ochre sail, sunset.
That photo exists. It was taken in Ha Long Bay. It’s from the 1990s.
Today, getting that frame without 40 boats in it means waking at 4 a.m. No guarantee. In 2025:
3.5 million tourists (official count, Ha Long Bay-Yen Tu World Heritage Management Board).
Five hundred junks daily. Some routes are so busy you could put traffic lights there.
So why mention it? Because it’s the gateway. Without Ha Long you wouldn’t be reading this. And because the weather we’ll break down here applies to the whole region, not just the overcrowded bay.
Local weather breakdown
- • March–April: 20–26°C, water 23°C, rain rare. In Ha Long: 3,000 tourists a day at the same spots.
- • May–June: 25–31°C, water 27°C, short storms. In Ha Long: “calmer” season, but still packed.
- • July–August: 30–35°C, water 30°C, possible typhoons. In Ha Long: frequent cancellations, or jammed if weather holds.
- • September: 25–30°C, water 28°C, rain tapering off. In Ha Long: international groups return, prices rise.
- • October–November: 20–28°C, water 26°C, almost no rain. In Ha Long: hell. Peak high season.
- • December–February: 15–20°C, water 19°C, very little rain. In Ha Long: cold, fewer people, but still crowded.
Almost mystical light of January in Halong BayLocal weather in short
March–April and October–November are the window. July–August is typhoon roulette. December–February works if you handle 15°C.
But when it’s perfect, everyone goes. And the magic vanishes. Fast.
Same weather, two worlds
The
Halong archipelago has 1,600 islands. Ha Long Bay is only a fraction. Thirty kilometers south,
Lan Ha Bay sits on the same latitude, same water, same karst towers.
But above all, it gives access to
Cat Ba Island and its national park: 17,000 hectares of primary jungle, 150 km² of protected sea, 80 bird species, 20 mammals (macaques, civets), and a few trails where you’ll meet almost no one.
Same sky. Two ways of seeing it.
For lovers of raw adventure
Why settle for a view from an upper deck when you can set foot in primary jungle? Where Ha Long serves queues, Mr Linh’s Adventures takes small groups into
Cat Ba National Park, in
Lan Ha Bay.
►
Cat Ba Trekking & Kayaking 3 days 2 nights
Ngu Lam Peak, the main summit of Cat Ba Island | Mr Linh's AdventuresWhat the seasons actually look like
In March or April, 22°C, clear blue sky, low humidity. In Ha Long it’s chaos with 3,000 tourists a day. On Cat Ba, it’s the start of trek season.
You climb in the morning, swim in 23°C water in the afternoon, and sleep in a lodge on the forest edge.
In May–June humidity rises. 25–31°C, violent short storms in late afternoon. In Ha Long groups still flock because it’s the “quiet season” and prices dip a bit. In Lan Ha, Cat Ba’s vegetation goes wild; water warms to 27°C. You can swim for hours without a chill. It’s tough‑trek season. Coastal trails get muddy and slippery. You alternate with kayaking to cool off.
July–August : roulette. Thermometer to 35°C, typhoon risk, torrential rain. In Ha Long cruises cancel or run anyway, packed with tourists who’ve paid. In Lan Ha you gamble between depressions. When water tops 29°C, billions of microorganisms begin to glow: a paddle can turn your wake into a trail of stars; dip your hand and it sparkles like you’ve caught the Milky Way. Don’t go out if a typhoon is forecast. But when the weather clears, you can be truly alone.
Same sky, two worlds | Mr Linh's Adventures
September: rains ease, typhoons move north. 25–30°C, flat sea, max visibility. Ha Long prices climb, international groups return. In Cat Ba park it’s time for long crossings, linking summits and caves on foot. In Lan Ha the sea is a mirror; underwater visibility maxes at 10–15 m. Night kayaking along islands, no waves, no wind, just the sound of oars cutting black water.
October–November is climatic perfection. Air 24°C, water 26°C, ultramarine sky, no rain. In Ha Long: the nightmare. Peak season, 5,000 people a day, queues to climb islands, strangers in your photos. In Lan Ha it’s “the season” too, but with perhaps ten boats across the bay versus hundreds elsewhere. You climb, dive, hike Cat Ba’s 17,000 hectares, cycle empty roads.
December–February brings cold. 15–20°C, morning mists, water down to 19°C. In Ha Long it’s low season: fewer people, but still a crowd. In the park it’s endurance trekking time.
The jungle is silent. Snakes sleep, insects vanish. You walk faster to warm up. Mists make cinematic scenes; peaks clear for spectacular views when sun breaks. And above all: you are alone. Really alone.
Note: watch the Tet holiday (late January to around February) when Lunar New Year paralyzes the country for about a week. Some restaurants close, some boats stay in port. Plan buffer days.
Lan Ha Bay, drone view | Mr Linh's AdventuresSo : when do you go?
The
Halong archipelago is mild eight months out of twelve. The issue isn’t the climate ; it's where you have to endure it.
In Ha Long, even perfect weather is ruined by crowds.
In Lan Ha, the same weather becomes an adventure.
Mr Linh’s Adventures runs Lan Ha/Cat Ba trips of 1–3 days: hiking, kayaking, climbing. Small groups, big space.
Call us now!You can’t control the weather. You can choose where to live it.