Cát Bà weather in April
In April, Cát Bà sees average daytime highs of 25°C and overnight lows near 23°C, with 52 mm of rain across 7.7 wet days and about 12.5 hours of daylight. It is the 7th-warmest and 8th-wettest month of the year here.
Highs climb over the month, from about 23°C in the first days to 26°C by the end. The sky is clear or mostly clear about 22% of the time in April, and the air most often feels oppressive.
Daylight stretches from about 12 h 12 min at the start of April to 12 h 42 min by month's end. Set against the rest of the year, April is Cát Bà's 4th-clearest and 9th-windiest month. For the whole year in context, see Cát Bà's year-round climate.
- Daytime high
- 25°
- 7th warmest
- Overnight low
- 23°
- 6th coldest
- Rainfall
- 52 mm
- 7.7 wet days
- Daylight
- 12 h 30 min
- 5:38 AM – 6:06 PM
- Cloud cover
- 64%
- 4th clearest
- Wind
- 15 km/h
- 9th windiest
- Solar energy
- 4.96 kWh/m²
- Travel score
- 7.0
- out of 10
Cát Bà is town in Vietnam.
Air quality: WHO Ambient Air Quality Database. Density & description: Wikidata (CC0), GeoNames.
Temperature in April
Highs climb over the month, from about 23°C in the first days to 26°C by the end.
A typical April day in Cát Bà reaches about 25°C in the afternoon and slips back to 23°C overnight — a 2°C spread between the day's warmth and the night's chill. On most days the high lands between 22°C and 27°C. Set against its neighbours, April runs about 3°C warmer than March and about 4°C cooler than May.
| 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 | 10 | 11 | 12 | 13 | 14 | 15 | 16 | 17 | 18 | 19 | 20 | 21 | 22 | 23 | 24 | 25 | 26 | 27 | 28 | 29 | 30 | |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Avg high (°C) | 23 | 23 | 23 | 23 | 23 | 23 | 24 | 24 | 24 | 24 | 24 | 24 | 24 | 25 | 25 | 25 | 25 | 25 | 25 | 25 | 25 | 26 | 26 | 26 | 26 | 26 | 26 | 26 | 26 | 27 |
| Avg low (°C) | 21 | 21 | 21 | 21 | 21 | 21 | 22 | 22 | 22 | 22 | 22 | 22 | 22 | 22 | 23 | 23 | 23 | 23 | 23 | 23 | 23 | 24 | 24 | 24 | 24 | 24 | 24 | 24 | 24 | 24 |
| Avg high (°C) | Avg low (°C) | |
|---|---|---|
| 1 | 23 | 21 |
| 2 | 23 | 21 |
| 3 | 23 | 21 |
| 4 | 23 | 21 |
| 5 | 23 | 21 |
| 6 | 23 | 21 |
| 7 | 24 | 22 |
| 8 | 24 | 22 |
| 9 | 24 | 22 |
| 10 | 24 | 22 |
| 11 | 24 | 22 |
| 12 | 24 | 22 |
| 13 | 24 | 22 |
| 14 | 25 | 22 |
| 15 | 25 | 23 |
| 16 | 25 | 23 |
| 17 | 25 | 23 |
| 18 | 25 | 23 |
| 19 | 25 | 23 |
| 20 | 25 | 23 |
| 21 | 25 | 23 |
| 22 | 26 | 24 |
| 23 | 26 | 24 |
| 24 | 26 | 24 |
| 25 | 26 | 24 |
| 26 | 26 | 24 |
| 27 | 26 | 24 |
| 28 | 26 | 24 |
| 29 | 26 | 24 |
| 30 | 27 | 24 |
How April really feels in Cát Bà
Once humidity and wind are folded in, April averages 0 days that feel above 32°C and 0 that feel at or below 0°C — the comfort signal a plain temperature reading hides.
April 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 April compares with the rest of the year at a glance. April is the 7th-warmest and 8th-wettest month here — the current month is highlighted below.
| 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 April
The sky is clear or mostly clear about 22% of the time in April.
Beyond those clear spells, partly cloudy skies cover about 20% of April, with mostly cloudy or overcast conditions the remaining 58%.
| 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 | 10 | 11 | 12 | 13 | 14 | 15 | 16 | 17 | 18 | 19 | 20 | 21 | 22 | 23 | 24 | 25 | 26 | 27 | 28 | 29 | 30 | |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Clearer (%) | 32 | 33 | 34 | 34 | 35 | 37 | 37 | 38 | 38 | 39 | 40 | 41 | 42 | 43 | 44 | 45 | 45 | 45 | 46 | 45 | 46 | 46 | 46 | 46 | 47 | 47 | 46 | 46 | 46 | 45 |
| Cloudier (%) | 68 | 67 | 66 | 66 | 65 | 63 | 63 | 62 | 62 | 61 | 60 | 59 | 58 | 57 | 56 | 55 | 55 | 55 | 54 | 55 | 54 | 54 | 54 | 54 | 53 | 53 | 54 | 54 | 54 | 55 |
| Clearer (%) | Cloudier (%) | |
|---|---|---|
| 1 | 32 | 68 |
| 2 | 33 | 67 |
| 3 | 34 | 66 |
| 4 | 34 | 66 |
| 5 | 35 | 65 |
| 6 | 37 | 63 |
| 7 | 37 | 63 |
| 8 | 38 | 62 |
| 9 | 38 | 62 |
| 10 | 39 | 61 |
| 11 | 40 | 60 |
| 12 | 41 | 59 |
| 13 | 42 | 58 |
| 14 | 43 | 57 |
| 15 | 44 | 56 |
| 16 | 45 | 55 |
| 17 | 45 | 55 |
| 18 | 45 | 55 |
| 19 | 46 | 54 |
| 20 | 45 | 55 |
| 21 | 46 | 54 |
| 22 | 46 | 54 |
| 23 | 46 | 54 |
| 24 | 46 | 54 |
| 25 | 47 | 53 |
| 26 | 47 | 53 |
| 27 | 46 | 54 |
| 28 | 46 | 54 |
| 29 | 46 | 54 |
| 30 | 45 | 55 |
Chance of precipitation in April
Cát Bà gets around 52 mm of rain over 7.7 wet days in April. The line is the day-by-day chance of measurable precipitation.
Day to day, the chance of measurable rain averages around 27% and peaks near 36% on the wettest days. The odds climb toward the end of the month.
| 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 | 10 | 11 | 12 | 13 | 14 | 15 | 16 | 17 | 18 | 19 | 20 | 21 | 22 | 23 | 24 | 25 | 26 | 27 | 28 | 29 | 30 | |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Rain chance (%) | 27 | 27 | 27 | 27 | 27 | 26 | 26 | 25 | 25 | 25 | 24 | 24 | 24 | 24 | 24 | 24 | 24 | 24 | 25 | 25 | 26 | 26 | 27 | 28 | 29 | 30 | 32 | 33 | 35 | 36 |
| Rain chance (%) | |
|---|---|
| 1 | 27 |
| 2 | 27 |
| 3 | 27 |
| 4 | 27 |
| 5 | 27 |
| 6 | 26 |
| 7 | 26 |
| 8 | 25 |
| 9 | 25 |
| 10 | 25 |
| 11 | 24 |
| 12 | 24 |
| 13 | 24 |
| 14 | 24 |
| 15 | 24 |
| 16 | 24 |
| 17 | 24 |
| 18 | 24 |
| 19 | 25 |
| 20 | 25 |
| 21 | 26 |
| 22 | 26 |
| 23 | 27 |
| 24 | 28 |
| 25 | 29 |
| 26 | 30 |
| 27 | 32 |
| 28 | 33 |
| 29 | 35 |
| 30 | 36 |
Humidity in April
Most of April feels oppressive — the stacked bands show each day's mix of comfort levels, read off the dew point.
By dew point, April lands in the oppressive band about 50% of days. Sticky, muggy-or-worse air turns up on roughly 84% of them.
| 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 | 10 | 11 | 12 | 13 | 14 | 15 | 16 | 17 | 18 | 19 | 20 | 21 | 22 | 23 | 24 | 25 | 26 | 27 | 28 | 29 | 30 | |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Dry (%) | 5 | 4 | 4 | 4 | 3 | 3 | 3 | 3 | 2 | 2 | 2 | 2 | 2 | 2 | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 |
| Comfortable (%) | 7 | 6 | 6 | 6 | 6 | 6 | 6 | 6 | 6 | 6 | 6 | 5 | 5 | 5 | 5 | 5 | 4 | 4 | 4 | 3 | 3 | 3 | 2 | 2 | 2 | 2 | 2 | 1 | 1 | 1 |
| Humid (%) | 16 | 15 | 15 | 15 | 14 | 14 | 14 | 13 | 13 | 12 | 12 | 11 | 11 | 10 | 10 | 10 | 9 | 9 | 8 | 8 | 7 | 7 | 6 | 6 | 6 | 5 | 5 | 5 | 5 | 5 |
| Muggy (%) | 39 | 39 | 37 | 35 | 34 | 32 | 31 | 29 | 28 | 26 | 25 | 23 | 22 | 21 | 20 | 19 | 18 | 18 | 17 | 17 | 16 | 16 | 15 | 15 | 14 | 14 | 13 | 13 | 13 | 13 |
| Oppressive (%) | 33 | 36 | 38 | 39 | 42 | 44 | 46 | 48 | 50 | 52 | 52 | 56 | 56 | 57 | 58 | 57 | 59 | 58 | 58 | 57 | 58 | 57 | 57 | 55 | 53 | 51 | 49 | 47 | 44 | 42 |
| Miserable (%) | 0 | 0 | 1 | 1 | 1 | 1 | 1 | 1 | 2 | 2 | 3 | 3 | 4 | 5 | 6 | 8 | 9 | 10 | 12 | 14 | 15 | 17 | 20 | 22 | 25 | 28 | 31 | 34 | 36 | 39 |
| Dry (%) | Comfortable (%) | Humid (%) | Muggy (%) | Oppressive (%) | Miserable (%) | |
|---|---|---|---|---|---|---|
| 1 | 5 | 7 | 16 | 39 | 33 | 0 |
| 2 | 4 | 6 | 15 | 39 | 36 | 0 |
| 3 | 4 | 6 | 15 | 37 | 38 | 1 |
| 4 | 4 | 6 | 15 | 35 | 39 | 1 |
| 5 | 3 | 6 | 14 | 34 | 42 | 1 |
| 6 | 3 | 6 | 14 | 32 | 44 | 1 |
| 7 | 3 | 6 | 14 | 31 | 46 | 1 |
| 8 | 3 | 6 | 13 | 29 | 48 | 1 |
| 9 | 2 | 6 | 13 | 28 | 50 | 2 |
| 10 | 2 | 6 | 12 | 26 | 52 | 2 |
| 11 | 2 | 6 | 12 | 25 | 52 | 3 |
| 12 | 2 | 5 | 11 | 23 | 56 | 3 |
| 13 | 2 | 5 | 11 | 22 | 56 | 4 |
| 14 | 2 | 5 | 10 | 21 | 57 | 5 |
| 15 | 1 | 5 | 10 | 20 | 58 | 6 |
| 16 | 1 | 5 | 10 | 19 | 57 | 8 |
| 17 | 1 | 4 | 9 | 18 | 59 | 9 |
| 18 | 1 | 4 | 9 | 18 | 58 | 10 |
| 19 | 1 | 4 | 8 | 17 | 58 | 12 |
| 20 | 1 | 3 | 8 | 17 | 57 | 14 |
| 21 | 1 | 3 | 7 | 16 | 58 | 15 |
| 22 | 0 | 3 | 7 | 16 | 57 | 17 |
| 23 | 0 | 2 | 6 | 15 | 57 | 20 |
| 24 | 0 | 2 | 6 | 15 | 55 | 22 |
| 25 | 0 | 2 | 6 | 14 | 53 | 25 |
| 26 | 0 | 2 | 5 | 14 | 51 | 28 |
| 27 | 0 | 2 | 5 | 13 | 49 | 31 |
| 28 | 0 | 1 | 5 | 13 | 47 | 34 |
| 29 | 0 | 1 | 5 | 13 | 44 | 36 |
| 30 | 0 | 1 | 5 | 13 | 42 | 39 |
Wind in April
Winds average 15 km/h in April.
Across April, daily wind ranges from about 15 km/h on the calmest days to 16 km/h at its breeziest. It stays fairly steady from day to day.
| 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 | 10 | 11 | 12 | 13 | 14 | 15 | 16 | 17 | 18 | 19 | 20 | 21 | 22 | 23 | 24 | 25 | 26 | 27 | 28 | 29 | 30 | |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Wind speed (km/h) | 15 | 15 | 15 | 15 | 15 | 15 | 15 | 15 | 15 | 15 | 15 | 15 | 15 | 15 | 15 | 15 | 15 | 15 | 15 | 15 | 15 | 15 | 15 | 15 | 15 | 15 | 15 | 15 | 16 | 16 |
| Feels | light breeze | light breeze | light breeze | light breeze | light breeze | light breeze | light breeze | light breeze | light breeze | light breeze | light breeze | light breeze | light breeze | light breeze | light breeze | light breeze | light breeze | light breeze | light breeze | light breeze | light breeze | light breeze | light breeze | light breeze | light breeze | light breeze | light breeze | light breeze | light breeze | light breeze |
| Wind speed (km/h) | Feels | |
|---|---|---|
| 1 | 15 | light breeze |
| 2 | 15 | light breeze |
| 3 | 15 | light breeze |
| 4 | 15 | light breeze |
| 5 | 15 | light breeze |
| 6 | 15 | light breeze |
| 7 | 15 | light breeze |
| 8 | 15 | light breeze |
| 9 | 15 | light breeze |
| 10 | 15 | light breeze |
| 11 | 15 | light breeze |
| 12 | 15 | light breeze |
| 13 | 15 | light breeze |
| 14 | 15 | light breeze |
| 15 | 15 | light breeze |
| 16 | 15 | light breeze |
| 17 | 15 | light breeze |
| 18 | 15 | light breeze |
| 19 | 15 | light breeze |
| 20 | 15 | light breeze |
| 21 | 15 | light breeze |
| 22 | 15 | light breeze |
| 23 | 15 | light breeze |
| 24 | 15 | light breeze |
| 25 | 15 | light breeze |
| 26 | 15 | light breeze |
| 27 | 15 | light breeze |
| 28 | 15 | light breeze |
| 29 | 16 | light breeze |
| 30 | 16 | light breeze |
Sunrise & sunset in April
Daylight runs from about 12 h 12 min at the start of April to 12 h 42 min by month's end. The lit band spans sunrise to sunset each day.
Days grow by about 30 minutes over April. Sunrise moves from 5:51 AM to 5:27 AM, and sunset from 6:02 PM to 6:11 PM.
| 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 | 10 | 11 | 12 | 13 | 14 | 15 | 16 | 17 | 18 | 19 | 20 | 21 | 22 | 23 | 24 | 25 | 26 | 27 | 28 | 29 | 30 | |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Daylight (h) | 12.2 | 12.2 | 12.2 | 12.2 | 12.3 | 12.3 | 12.3 | 12.3 | 12.3 | 12.4 | 12.4 | 12.4 | 12.4 | 12.4 | 12.5 | 12.5 | 12.5 | 12.5 | 12.5 | 12.6 | 12.6 | 12.6 | 12.6 | 12.6 | 12.6 | 12.7 | 12.7 | 12.7 | 12.7 | 12.7 |
| Sunrise (AM) | 5:51 | 5:50 | 5:49 | 5:48 | 5:47 | 5:47 | 5:46 | 5:45 | 5:44 | 5:43 | 5:42 | 5:41 | 5:40 | 5:39 | 5:39 | 5:38 | 5:37 | 5:36 | 5:35 | 5:35 | 5:34 | 5:33 | 5:32 | 5:31 | 5:31 | 5:30 | 5:29 | 5:29 | 5:28 | 5:27 |
| Sunset (PM) | 6:02 | 6:02 | 6:02 | 6:03 | 6:03 | 6:03 | 6:04 | 6:04 | 6:04 | 6:04 | 6:05 | 6:05 | 6:05 | 6:06 | 6:06 | 6:06 | 6:07 | 6:07 | 6:07 | 6:08 | 6:08 | 6:08 | 6:09 | 6:09 | 6:09 | 6:10 | 6:10 | 6:10 | 6:11 | 6:11 |
| Daylight (h) | Sunrise (AM) | Sunset (PM) | |
|---|---|---|---|
| 1 | 12.2 | 5:51 | 6:02 |
| 2 | 12.2 | 5:50 | 6:02 |
| 3 | 12.2 | 5:49 | 6:02 |
| 4 | 12.2 | 5:48 | 6:03 |
| 5 | 12.3 | 5:47 | 6:03 |
| 6 | 12.3 | 5:47 | 6:03 |
| 7 | 12.3 | 5:46 | 6:04 |
| 8 | 12.3 | 5:45 | 6:04 |
| 9 | 12.3 | 5:44 | 6:04 |
| 10 | 12.4 | 5:43 | 6:04 |
| 11 | 12.4 | 5:42 | 6:05 |
| 12 | 12.4 | 5:41 | 6:05 |
| 13 | 12.4 | 5:40 | 6:05 |
| 14 | 12.4 | 5:39 | 6:06 |
| 15 | 12.5 | 5:39 | 6:06 |
| 16 | 12.5 | 5:38 | 6:06 |
| 17 | 12.5 | 5:37 | 6:07 |
| 18 | 12.5 | 5:36 | 6:07 |
| 19 | 12.5 | 5:35 | 6:07 |
| 20 | 12.6 | 5:35 | 6:08 |
| 21 | 12.6 | 5:34 | 6:08 |
| 22 | 12.6 | 5:33 | 6:08 |
| 23 | 12.6 | 5:32 | 6:09 |
| 24 | 12.6 | 5:31 | 6:09 |
| 25 | 12.6 | 5:31 | 6:09 |
| 26 | 12.7 | 5:30 | 6:10 |
| 27 | 12.7 | 5:29 | 6:10 |
| 28 | 12.7 | 5:29 | 6:10 |
| 29 | 12.7 | 5:28 | 6:11 |
| 30 | 12.7 | 5:27 | 6:11 |
Solar energy in April
Average shortwave solar energy reaching the ground each day in April, about 4.96 kWh/m².
For context, solar energy here swings from a low near 2.74 kWh/m² to a high of 5.4 kWh/m² in May across the year — April's 4.96 kWh/m² falls in the middle.
| 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 | 10 | 11 | 12 | 13 | 14 | 15 | 16 | 17 | 18 | 19 | 20 | 21 | 22 | 23 | 24 | 25 | 26 | 27 | 28 | 29 | 30 | |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Solar energy (kWh/m²) | 4.3 | 4.3 | 4.3 | 4.4 | 4.4 | 4.5 | 4.5 | 4.6 | 4.6 | 4.7 | 4.8 | 4.8 | 4.9 | 4.9 | 5.0 | 5.0 | 5.1 | 5.1 | 5.2 | 5.2 | 5.3 | 5.3 | 5.3 | 5.3 | 5.4 | 5.4 | 5.4 | 5.4 | 5.4 | 5.4 |
| Level | Bright | Bright | Bright | Bright | Bright | Bright | Bright | Bright | Bright | Bright | Bright | Bright | Bright | Bright | Bright | Bright | Bright | Bright | Bright | Bright | Bright | Bright | Bright | Bright | Bright | Bright | Bright | Bright | Bright | Bright |
| Solar energy (kWh/m²) | Level | |
|---|---|---|
| 1 | 4.3 | Bright |
| 2 | 4.3 | Bright |
| 3 | 4.3 | Bright |
| 4 | 4.4 | Bright |
| 5 | 4.4 | Bright |
| 6 | 4.5 | Bright |
| 7 | 4.5 | Bright |
| 8 | 4.6 | Bright |
| 9 | 4.6 | Bright |
| 10 | 4.7 | Bright |
| 11 | 4.8 | Bright |
| 12 | 4.8 | Bright |
| 13 | 4.9 | Bright |
| 14 | 4.9 | Bright |
| 15 | 5.0 | Bright |
| 16 | 5.0 | Bright |
| 17 | 5.1 | Bright |
| 18 | 5.1 | Bright |
| 19 | 5.2 | Bright |
| 20 | 5.2 | Bright |
| 21 | 5.3 | Bright |
| 22 | 5.3 | Bright |
| 23 | 5.3 | Bright |
| 24 | 5.3 | Bright |
| 25 | 5.4 | Bright |
| 26 | 5.4 | Bright |
| 27 | 5.4 | Bright |
| 28 | 5.4 | Bright |
| 29 | 5.4 | Bright |
| 30 | 5.4 | Bright |
Hazard calendar for Cát Bà
In April, Cát Bà sits inside 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 April a good time to visit Cát Bà?
Our two travel scores rate April for general sightseeing and for beach or pool weather — 0 (poor) to 10 (ideal).
April is one of the better times to visit Cát Bà for general sightseeing. The water and warmth also suit a beach or pool day.
What to pack for Cát Bà in April
From April's temperature range, rain chance, sun and wind — what's worth putting in the bag.
In April, Cát Bà sees daytime highs around 25°C and nights near 23°C. Worth packing: light clothes and sun protection. About 8 days see rain.
Sea temperature near Cát Bà in April
The nearest coast averages about 23°C in April — 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 April
Clear-sky midday UV in April peaks around 8 (very high — sun protection essential). 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 April
Average fine-particle pollution (PM2.5) through the year — so you can see where April 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. Tropical-cyclone seasons are the published climatological basin seasons (NOAA National Hurricane Center / regional warning centres). Sea temperatures are the NOAA OISST v2.1 1991–2020 monthly climatology (public domain), sampled at the nearest ocean point. UV index is derived from CAMS (Copernicus Atmosphere Monitoring Service) clear-sky UV data — contains modified Copernicus Atmosphere Monitoring Service information. Monthly air-quality (PM2.5) seasonality is from the CAMS EAC4 reanalysis (Copernicus Atmosphere Monitoring Service), scaled to the WHO annual mean where available. Topography is sampled from the Copernicus DEM GLO-90 elevation model (© ESA/Airbus) and ESA WorldCover 2021 land cover (CC BY 4.0).