Cát Bà in Winter
In winter (December, January and February), Cát Bà sees average daytime highs around 19°C and overnight lows near 17°C, with 102 mm of rain over about 20 wet days across the season. It is the coldest season of the year and the driest season of the year.
Over the season highs ease from about 22°C in early December to 20°C by late February. The sky is clear or mostly clear about 23% of the time across winter, and the air most often feels dry.
Winter is Cát Bà's best season of the year to visit on our travel score. For the whole year in context, see Cát Bà's year-round climate.
- Avg daytime high
- 19°C
- coldest season of the year
- Avg overnight low
- 17°C
- Rainfall
- 102 mm
- 20 wet days
- Avg wind
- 16 km/h
- Travel score
- 6.5
- best season of the year
- Months
- Dec · Jan · Feb
Temperature in Cát Bà in Winter
Over the season highs ease from about 22°C in early December to 20°C by late February.
A typical winter day in Cát Bà reaches about 19°C and drops to 17°C overnight. The warmest of the three months is December, the coolest January.
How winter really feels in Cát Bà
Once humidity and wind are folded in, winter brings about 0 days that feel above 32°C and 0 that feel at or below 0°C.
winter sits comfortably in between — no days that feel dangerously hot or drop to a hard freeze once humidity and wind are folded in.
Cát Bà weather by month
How the three winter months (December, January and February) compare with the rest of the year — the season's months are highlighted.
| Month | High / Low (°C) | Rainfall (mm) | Wet days | Daylight (hours) | Travel score |
|---|---|---|---|---|---|
| Jan | 19° / 16° | 40 | 7.6 | 10.9 | 6.2 |
| Feb | 19° / 17° | 23 | 5.7 | 11.3 | 6.4 |
| Mar | 21° / 19° | 40 | 7.6 | 11.9 | 6.6 |
| Apr | 25° / 23° | 52 | 7.7 | 12.5 | 7.0 |
| May | 28° / 26° | 185 | 15.5 | 13 | 5.1 |
| Jun | 30° / 28° | 215 | 17.8 | 13.2 | 3.7 |
| Jul | 30° / 28° | 303 | 19.8 | 13.1 | 3.6 |
| Aug | 30° / 27° | 399 | 24 | 12.7 | 3.3 |
| Sep | 29° / 26° | 305 | 20 | 12.1 | 4.0 |
| Oct | 28° / 25° | 134 | 11.6 | 11.5 | 6.2 |
| Nov | 24° / 21° | 56 | 8.4 | 11 | 7.2 |
| Dec | 21° / 18° | 39 | 6.3 | 10.8 | 6.9 |
Cloud cover in Winter
The sky is clear or mostly clear about 23% of the time across winter.
Chance of precipitation in Winter
Cát Bà gets around 102 mm of rain over 20 wet days across winter. The line is the day-by-day chance of measurable precipitation.
Humidity in Winter
Most of winter feels dry — the stacked bands show each day's mix of comfort levels, read off the dew point.
Wind in Winter
Winds average 16 km/h across winter.
Sunrise & sunset in Winter
Daylight runs from about 10 h 48 min in early December to 11 h 30 min by late February. The lit band spans sunrise to sunset each day.
Solar energy in Winter
Average shortwave solar energy reaching the ground each day across winter, about 2.9 kWh/m².
Hazard calendar for Cát Bà
In winter, Cát Bà overlaps its pacific typhoon season. The full year is below, with each hazard's peak months called out.
Cát Bà sits in the Pacific typhoon belt; the season peaks July–October.
Cát Bà's monsoon runs May–September, when most of the year's rain falls.
Is winter a good time to visit Cát Bà?
Our two travel scores rate winter for general sightseeing and for beach or pool weather — 0 (poor) to 10 (ideal), averaged across the three months.
winter is a reasonable time to visit Cát Bà for sightseeing.
What to pack for Cát Bà in Winter
From winter's temperature range, rain chance, sun and wind — what's worth putting in the bag.
In winter, Cát Bà sees daytime highs around 19°C and nights near 17°C. Little to plan around — just the basics. About 20 days see rain.
Sea temperature near Cát Bà in Winter
The nearest coast averages about 21°C across winter — the other half of the beach question. The full-year curve and swim-comfort zones are below.
The sea at the nearest coast (about 14 km away) is warmest in August at about 30°C and coldest in February near 20°C.
It's comfortable for a long swim from Mar 6 to Jan 18 — about 10.5 months when the water holds above 20°C.
| Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Sea temperature (°C) | 20 | 20 | 20 | 23 | 27 | 29 | 30 | 30 | 29 | 28 | 25 | 22 |
| Comfort | Refreshing | Cool | Refreshing | Refreshing | Warm | Tropical | Tropical | Tropical | Tropical | Warm | Warm | Refreshing |
| Sea temperature (°C) | Comfort | |
|---|---|---|
| Jan | 20 | Refreshing |
| Feb | 20 | Cool |
| Mar | 20 | Refreshing |
| Apr | 23 | Refreshing |
| May | 27 | Warm |
| Jun | 29 | Tropical |
| Jul | 30 | Tropical |
| Aug | 30 | Tropical |
| Sep | 29 | Tropical |
| Oct | 28 | Warm |
| Nov | 25 | Warm |
| Dec | 22 | Refreshing |
UV index in Cát Bà in Winter
Clear-sky midday UV across winter averages around 7 — enough to warrant sun protection. The full-year curve, shaded by WHO exposure level, is below.
Under clear skies, the midday UV index in Cát Bà peaks around July 12 at about 12 (extreme) — sunscreen, a hat and midday shade are essential. It bottoms out near December 19 at about 6 (high).
The index reaches 3 or more — the level where the WHO recommends sun protection — every month of the year.
| Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| UV index (midday) | 7 | 8 | 9 | 8 | 10 | 12 | 12 | 9 | 9 | 9 | 7 | 6 |
| Level | High | Very high | Very high | Very high | Extreme | Extreme | Extreme | Very high | Very high | Very high | High | High |
| UV index (midday) | Level | |
|---|---|---|
| Jan | 7 | High |
| Feb | 8 | Very high |
| Mar | 9 | Very high |
| Apr | 8 | Very high |
| May | 10 | Extreme |
| Jun | 12 | Extreme |
| Jul | 12 | Extreme |
| Aug | 9 | Very high |
| Sep | 9 | Very high |
| Oct | 9 | Very high |
| Nov | 7 | High |
| Dec | 6 | High |
Air quality in Cát Bà in Winter
Average fine-particle pollution (PM2.5) through the year — so you can see where winter falls, not just the annual average.
Air quality in Cát Bà is worst in January — around 42 µg/m³ PM2.5 (poor), about 2.6× the cleanest month (July, 16 µg/m³).
Modeled monthly averages (CAMS reanalysis, 2015–2024).
| Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| PM2.5 (µg/m³) | 42 | 42 | 41 | 40 | 26 | 19 | 16 | 18 | 21 | 27 | 29 | 39 |
| Level | Poor | Poor | Poor | Poor | Moderate | Moderate | Moderate | Moderate | Moderate | Moderate | Moderate | Poor |
| PM2.5 (µg/m³) | Level | |
|---|---|---|
| Jan | 42 | Poor |
| Feb | 42 | Poor |
| Mar | 41 | Poor |
| Apr | 40 | Poor |
| May | 26 | Moderate |
| Jun | 19 | Moderate |
| Jul | 16 | Moderate |
| Aug | 18 | Moderate |
| Sep | 21 | Moderate |
| Oct | 27 | Moderate |
| Nov | 29 | Moderate |
| Dec | 39 | Poor |
Where is Cát Bà?
Cát Bà sits at 20.7°N, 107.0°E, 24 m above sea level, in Vietnam. The nearest listed city is Ha Long, 25 km away.
Topography around Cát Bà
How much the land rises and falls, and what covers it, within 3, 16 and 80 km of Cát Bà.
Within 3 km, the terrain around Cát Bà has only modest variations in elevation — a maximum elevation change of 205 m around an average of 22 m above sea level; within 16 km, significant variations in elevation — a maximum elevation change of 299 m; within 80 km, large variations in elevation — a maximum elevation change of 1,180 m.
The land around Cát Bà is covered by water (58%) and trees (36%) within 3 km, water (80%) within 16 km, and water (51%) and trees (29%) within 80 km.
Vietnam travel facts
- Travel advisory
- Level 1
- Exercise Normal Precautions
- Power plugs
- Type A / B / C / F
- 220 V · 50 Hz
- Prices
- ≈ 29% of US
- price level, 2025
- GDP per capita
- $5,066
- 2025
- Happiness
- 6.4 / 10
- World Happiness, 2025
- Safe drinking water
- 59%
- of population, 2024
- Homicide rate
- 1.5
- per 100k, 2011
- Road deaths
- 30.6
- per 100k/yr, 2019
- Income group
- Upper middle
- World Bank
- English
- Moderate
- EF EPI 500
- Religion
Sources: World Bank, US State Department, World Happiness Report, WHO/UNICEF, EF EPI, CIA World Factbook.
Data sources
Temperature, precipitation, cloud, humidity, wind and solar figures are a 1991–2020 climatology for Cát Bà (20.7278°, 107.0482°, elevation 24 m), computed from hourly ERA5 reanalysis — contains modified Copernicus Climate Change Service information. Sun figures are astronomical calculations, not observations. City data © GeoNames, CC BY 4.0. Map outlines from Natural Earth (public domain); interactive map © Google.