Ha Long weather in May
In May, Ha Long sees average daytime highs of 30°C and overnight lows near 25°C, with 219 mm of rain across 19.5 wet days and about 13 hours of daylight. It is the 5th-warmest and 5th-wettest month of the year here.
Highs climb over the month, from about 29°C in the first days to 31°C by the end. The sky is clear or mostly clear about 13% of the time in May, and the air most often feels miserable.
Daylight stretches from about 12 h 48 min at the start of May to 13 h 12 min by month's end. Set against the rest of the year, May is Ha Long's 7th-clearest and 3rd-windiest month. For the whole year in context, see Ha Long's year-round climate.
- Daytime high
- 30°
- 5th warmest
- Overnight low
- 25°
- 8th coldest
- Rainfall
- 219 mm
- 19.5 wet days
- Daylight
- 13 hours
- 5:18 AM – 6:18 PM
- Cloud cover
- 74%
- 7th clearest
- Wind
- 11 km/h
- 3rd windiest
- Solar energy
- 5.07 kWh/m²
- Travel score
- 3.9
- out of 10
Ha Long is provincial city of Vietnam.
- Air quality
- Elevated
- PM10 47 µg/m³ · 2015
- Density
- 993/km²
- people per km²
Air quality: WHO Ambient Air Quality Database. Density & description: Wikidata (CC0), GeoNames.
Temperature in May
Highs climb over the month, from about 29°C in the first days to 31°C by the end.
A typical May day in Ha Long reaches about 30°C in the afternoon and slips back to 25°C overnight — a 5°C spread between the day's warmth and the night's chill. On most days the high lands between 27°C and 33°C. Set against its neighbours, May runs about 4°C warmer than April and about 2°C cooler than June.
| 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 | 31 | |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Avg high (°C) | 28 | 29 | 29 | 29 | 29 | 29 | 29 | 29 | 29 | 29 | 29 | 29 | 30 | 30 | 30 | 30 | 30 | 30 | 30 | 30 | 30 | 30 | 30 | 30 | 30 | 31 | 31 | 31 | 31 | 31 | 31 |
| Avg low (°C) | 24 | 24 | 24 | 24 | 24 | 24 | 24 | 24 | 24 | 24 | 24 | 25 | 25 | 25 | 25 | 25 | 25 | 25 | 25 | 25 | 25 | 25 | 25 | 25 | 25 | 25 | 26 | 26 | 26 | 26 | 26 |
| Avg high (°C) | Avg low (°C) | |
|---|---|---|
| 1 | 28 | 24 |
| 2 | 29 | 24 |
| 3 | 29 | 24 |
| 4 | 29 | 24 |
| 5 | 29 | 24 |
| 6 | 29 | 24 |
| 7 | 29 | 24 |
| 8 | 29 | 24 |
| 9 | 29 | 24 |
| 10 | 29 | 24 |
| 11 | 29 | 24 |
| 12 | 29 | 25 |
| 13 | 30 | 25 |
| 14 | 30 | 25 |
| 15 | 30 | 25 |
| 16 | 30 | 25 |
| 17 | 30 | 25 |
| 18 | 30 | 25 |
| 19 | 30 | 25 |
| 20 | 30 | 25 |
| 21 | 30 | 25 |
| 22 | 30 | 25 |
| 23 | 30 | 25 |
| 24 | 30 | 25 |
| 25 | 30 | 25 |
| 26 | 31 | 25 |
| 27 | 31 | 26 |
| 28 | 31 | 26 |
| 29 | 31 | 26 |
| 30 | 31 | 26 |
| 31 | 31 | 26 |
How May really feels in Ha Long
Once humidity and wind are folded in, May averages 29 days that feel above 32°C and 0 that feel at or below 0°C — the comfort signal a plain temperature reading hides.
The story in May is heat — humidity pushes the afternoon "feels like" well above the raw temperature.
Ha Long weather by month
How May compares with the rest of the year at a glance. May is the 5th-warmest and 5th-wettest month here — the current month is highlighted below.
| Month | High / Low (°C) | Rainfall (mm) | Wet days | Daylight (hours) | Travel score |
|---|---|---|---|---|---|
| Jan | 19° / 15° | 34 | 6.5 | 10.9 | 6.3 |
| Feb | 20° / 16° | 21 | 5.6 | 11.3 | 6.4 |
| Mar | 22° / 18° | 44 | 8.8 | 11.9 | 6.5 |
| Apr | 26° / 22° | 69 | 11.6 | 12.5 | 6.0 |
| May | 30° / 25° | 219 | 19.5 | 13 | 3.9 |
| Jun | 31° / 27° | 266 | 22.4 | 13.2 | 2.9 |
| Jul | 31° / 27° | 305 | 24.3 | 13.1 | 2.8 |
| Aug | 31° / 26° | 381 | 26.2 | 12.7 | 2.7 |
| Sep | 30° / 25° | 243 | 20 | 12.1 | 3.6 |
| Oct | 28° / 23° | 104 | 11.9 | 11.5 | 5.7 |
| Nov | 25° / 19° | 51 | 8.2 | 11 | 7.1 |
| Dec | 21° / 16° | 31 | 5.9 | 10.8 | 7.0 |
Cloud cover in May
The sky is clear or mostly clear about 13% of the time in May.
Beyond those clear spells, partly cloudy skies cover about 14% of May, with mostly cloudy or overcast conditions the remaining 72%.
| 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 | 31 | |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Clearer (%) | 32 | 33 | 33 | 33 | 34 | 35 | 34 | 34 | 34 | 34 | 34 | 33 | 33 | 30 | 30 | 29 | 29 | 27 | 26 | 25 | 24 | 23 | 22 | 21 | 21 | 19 | 19 | 19 | 18 | 18 | 17 |
| Cloudier (%) | 68 | 67 | 67 | 67 | 66 | 65 | 66 | 66 | 66 | 66 | 66 | 67 | 67 | 70 | 70 | 71 | 71 | 73 | 74 | 75 | 76 | 77 | 78 | 79 | 79 | 81 | 81 | 81 | 82 | 82 | 83 |
| Clearer (%) | Cloudier (%) | |
|---|---|---|
| 1 | 32 | 68 |
| 2 | 33 | 67 |
| 3 | 33 | 67 |
| 4 | 33 | 67 |
| 5 | 34 | 66 |
| 6 | 35 | 65 |
| 7 | 34 | 66 |
| 8 | 34 | 66 |
| 9 | 34 | 66 |
| 10 | 34 | 66 |
| 11 | 34 | 66 |
| 12 | 33 | 67 |
| 13 | 33 | 67 |
| 14 | 30 | 70 |
| 15 | 30 | 70 |
| 16 | 29 | 71 |
| 17 | 29 | 71 |
| 18 | 27 | 73 |
| 19 | 26 | 74 |
| 20 | 25 | 75 |
| 21 | 24 | 76 |
| 22 | 23 | 77 |
| 23 | 22 | 78 |
| 24 | 21 | 79 |
| 25 | 21 | 79 |
| 26 | 19 | 81 |
| 27 | 19 | 81 |
| 28 | 19 | 81 |
| 29 | 18 | 82 |
| 30 | 18 | 82 |
| 31 | 17 | 83 |
Chance of precipitation in May
Ha Long gets around 219 mm of rain over 19.5 wet days in May. The line is the day-by-day chance of measurable precipitation.
Day to day, the chance of measurable rain averages around 62% and peaks near 71% 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 | 31 | |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Rain chance (%) | 51 | 52 | 53 | 54 | 55 | 56 | 57 | 58 | 59 | 59 | 60 | 60 | 61 | 61 | 62 | 62 | 63 | 64 | 64 | 65 | 66 | 66 | 67 | 67 | 68 | 68 | 69 | 69 | 70 | 70 | 71 |
| Rain chance (%) | |
|---|---|
| 1 | 51 |
| 2 | 52 |
| 3 | 53 |
| 4 | 54 |
| 5 | 55 |
| 6 | 56 |
| 7 | 57 |
| 8 | 58 |
| 9 | 59 |
| 10 | 59 |
| 11 | 60 |
| 12 | 60 |
| 13 | 61 |
| 14 | 61 |
| 15 | 62 |
| 16 | 62 |
| 17 | 63 |
| 18 | 64 |
| 19 | 64 |
| 20 | 65 |
| 21 | 66 |
| 22 | 66 |
| 23 | 67 |
| 24 | 67 |
| 25 | 68 |
| 26 | 68 |
| 27 | 69 |
| 28 | 69 |
| 29 | 70 |
| 30 | 70 |
| 31 | 71 |
Humidity in May
Most of May feels miserable — the stacked bands show each day's mix of comfort levels, read off the dew point.
By dew point, May lands in the miserable band about 58% of days. Sticky, muggy-or-worse air turns up on roughly 97% 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 | 31 | |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Comfortable (%) | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 |
| Humid (%) | 6 | 5 | 5 | 4 | 4 | 4 | 3 | 3 | 3 | 3 | 3 | 3 | 2 | 2 | 2 | 2 | 2 | 2 | 2 | 2 | 2 | 2 | 2 | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 1 |
| Muggy (%) | 15 | 15 | 14 | 14 | 13 | 13 | 13 | 12 | 12 | 12 | 12 | 12 | 12 | 12 | 12 | 12 | 12 | 11 | 11 | 11 | 11 | 10 | 10 | 9 | 8 | 8 | 7 | 6 | 5 | 5 | 4 |
| Oppressive (%) | 45 | 44 | 42 | 41 | 39 | 38 | 36 | 35 | 33 | 32 | 31 | 29 | 28 | 28 | 27 | 26 | 26 | 25 | 25 | 24 | 23 | 23 | 22 | 21 | 21 | 20 | 19 | 18 | 17 | 16 | 15 |
| Miserable (%) | 32 | 35 | 37 | 40 | 42 | 44 | 47 | 49 | 51 | 52 | 53 | 55 | 57 | 57 | 58 | 59 | 59 | 61 | 61 | 62 | 63 | 65 | 66 | 69 | 70 | 71 | 73 | 75 | 77 | 78 | 80 |
| Comfortable (%) | Humid (%) | Muggy (%) | Oppressive (%) | Miserable (%) | |
|---|---|---|---|---|---|
| 1 | 1 | 6 | 15 | 45 | 32 |
| 2 | 1 | 5 | 15 | 44 | 35 |
| 3 | 1 | 5 | 14 | 42 | 37 |
| 4 | 1 | 4 | 14 | 41 | 40 |
| 5 | 1 | 4 | 13 | 39 | 42 |
| 6 | 1 | 4 | 13 | 38 | 44 |
| 7 | 1 | 3 | 13 | 36 | 47 |
| 8 | 1 | 3 | 12 | 35 | 49 |
| 9 | 1 | 3 | 12 | 33 | 51 |
| 10 | 1 | 3 | 12 | 32 | 52 |
| 11 | 1 | 3 | 12 | 31 | 53 |
| 12 | 1 | 3 | 12 | 29 | 55 |
| 13 | 1 | 2 | 12 | 28 | 57 |
| 14 | 1 | 2 | 12 | 28 | 57 |
| 15 | 1 | 2 | 12 | 27 | 58 |
| 16 | 1 | 2 | 12 | 26 | 59 |
| 17 | 1 | 2 | 12 | 26 | 59 |
| 18 | 1 | 2 | 11 | 25 | 61 |
| 19 | 1 | 2 | 11 | 25 | 61 |
| 20 | 1 | 2 | 11 | 24 | 62 |
| 21 | 1 | 2 | 11 | 23 | 63 |
| 22 | 0 | 2 | 10 | 23 | 65 |
| 23 | 0 | 2 | 10 | 22 | 66 |
| 24 | 0 | 1 | 9 | 21 | 69 |
| 25 | 0 | 1 | 8 | 21 | 70 |
| 26 | 0 | 1 | 8 | 20 | 71 |
| 27 | 0 | 1 | 7 | 19 | 73 |
| 28 | 0 | 1 | 6 | 18 | 75 |
| 29 | 0 | 1 | 5 | 17 | 77 |
| 30 | 0 | 1 | 5 | 16 | 78 |
| 31 | 0 | 1 | 4 | 15 | 80 |
Wind in May
Winds average 11 km/h in May.
Across May, daily wind ranges from about 10 km/h on the calmest days to 11 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 | 31 | |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Wind speed (km/h) | 11 | 11 | 11 | 11 | 11 | 11 | 11 | 11 | 11 | 11 | 11 | 11 | 11 | 11 | 11 | 11 | 11 | 11 | 11 | 11 | 11 | 11 | 11 | 11 | 11 | 11 | 11 | 11 | 11 | 10 | 10 |
| Feels | calm | calm | calm | calm | calm | calm | calm | calm | calm | calm | calm | calm | calm | calm | calm | calm | calm | calm | calm | calm | calm | calm | calm | calm | calm | calm | calm | calm | calm | calm | calm |
| Wind speed (km/h) | Feels | |
|---|---|---|
| 1 | 11 | calm |
| 2 | 11 | calm |
| 3 | 11 | calm |
| 4 | 11 | calm |
| 5 | 11 | calm |
| 6 | 11 | calm |
| 7 | 11 | calm |
| 8 | 11 | calm |
| 9 | 11 | calm |
| 10 | 11 | calm |
| 11 | 11 | calm |
| 12 | 11 | calm |
| 13 | 11 | calm |
| 14 | 11 | calm |
| 15 | 11 | calm |
| 16 | 11 | calm |
| 17 | 11 | calm |
| 18 | 11 | calm |
| 19 | 11 | calm |
| 20 | 11 | calm |
| 21 | 11 | calm |
| 22 | 11 | calm |
| 23 | 11 | calm |
| 24 | 11 | calm |
| 25 | 11 | calm |
| 26 | 11 | calm |
| 27 | 11 | calm |
| 28 | 11 | calm |
| 29 | 11 | calm |
| 30 | 10 | calm |
| 31 | 10 | calm |
Sunrise & sunset in May
Daylight runs from about 12 h 48 min at the start of May to 13 h 12 min by month's end. The lit band spans sunrise to sunset each day.
Days grow by about 24 minutes over May. Sunrise moves from 5:26 AM to 5:14 AM, and sunset from 6:12 PM to 6:24 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 | 31 | |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Daylight (h) | 12.8 | 12.8 | 12.8 | 12.8 | 12.8 | 12.8 | 12.9 | 12.9 | 12.9 | 12.9 | 12.9 | 12.9 | 13.0 | 13.0 | 13.0 | 13.0 | 13.0 | 13.0 | 13.0 | 13.0 | 13.1 | 13.1 | 13.1 | 13.1 | 13.1 | 13.1 | 13.1 | 13.1 | 13.1 | 13.2 | 13.2 |
| Sunrise (AM) | 5:26 | 5:26 | 5:25 | 5:24 | 5:24 | 5:23 | 5:23 | 5:22 | 5:21 | 5:21 | 5:20 | 5:20 | 5:19 | 5:19 | 5:19 | 5:18 | 5:18 | 5:17 | 5:17 | 5:17 | 5:16 | 5:16 | 5:16 | 5:15 | 5:15 | 5:15 | 5:15 | 5:15 | 5:14 | 5:14 | 5:14 |
| Sunset (PM) | 6:12 | 6:12 | 6:12 | 6:13 | 6:13 | 6:14 | 6:14 | 6:14 | 6:15 | 6:15 | 6:16 | 6:16 | 6:17 | 6:17 | 6:17 | 6:18 | 6:18 | 6:19 | 6:19 | 6:19 | 6:20 | 6:20 | 6:21 | 6:21 | 6:22 | 6:22 | 6:22 | 6:23 | 6:23 | 6:24 | 6:24 |
| Daylight (h) | Sunrise (AM) | Sunset (PM) | |
|---|---|---|---|
| 1 | 12.8 | 5:26 | 6:12 |
| 2 | 12.8 | 5:26 | 6:12 |
| 3 | 12.8 | 5:25 | 6:12 |
| 4 | 12.8 | 5:24 | 6:13 |
| 5 | 12.8 | 5:24 | 6:13 |
| 6 | 12.8 | 5:23 | 6:14 |
| 7 | 12.9 | 5:23 | 6:14 |
| 8 | 12.9 | 5:22 | 6:14 |
| 9 | 12.9 | 5:21 | 6:15 |
| 10 | 12.9 | 5:21 | 6:15 |
| 11 | 12.9 | 5:20 | 6:16 |
| 12 | 12.9 | 5:20 | 6:16 |
| 13 | 13.0 | 5:19 | 6:17 |
| 14 | 13.0 | 5:19 | 6:17 |
| 15 | 13.0 | 5:19 | 6:17 |
| 16 | 13.0 | 5:18 | 6:18 |
| 17 | 13.0 | 5:18 | 6:18 |
| 18 | 13.0 | 5:17 | 6:19 |
| 19 | 13.0 | 5:17 | 6:19 |
| 20 | 13.0 | 5:17 | 6:19 |
| 21 | 13.1 | 5:16 | 6:20 |
| 22 | 13.1 | 5:16 | 6:20 |
| 23 | 13.1 | 5:16 | 6:21 |
| 24 | 13.1 | 5:15 | 6:21 |
| 25 | 13.1 | 5:15 | 6:22 |
| 26 | 13.1 | 5:15 | 6:22 |
| 27 | 13.1 | 5:15 | 6:22 |
| 28 | 13.1 | 5:15 | 6:23 |
| 29 | 13.1 | 5:14 | 6:23 |
| 30 | 13.2 | 5:14 | 6:24 |
| 31 | 13.2 | 5:14 | 6:24 |
Solar energy in May
Average shortwave solar energy reaching the ground each day in May, about 5.07 kWh/m² — the sunniest month for solar.
For context, solar energy here swings from a low near 2.58 kWh/m² to a high of 5.07 kWh/m² in May across the year — May's 5.07 kWh/m² sits near the top of that range.
| 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 | 31 | |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Solar energy (kWh/m²) | 5.1 | 5.1 | 5.1 | 5.1 | 5.1 | 5.1 | 5.1 | 5.1 | 5.1 | 5.1 | 5.1 | 5.1 | 5.1 | 5.1 | 5.1 | 5.1 | 5.1 | 5.1 | 5.1 | 5.0 | 5.0 | 5.0 | 5.0 | 5.0 | 5.0 | 5.0 | 5.0 | 5.0 | 5.0 | 5.0 | 5.0 |
| 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 | Bright |
| Solar energy (kWh/m²) | Level | |
|---|---|---|
| 1 | 5.1 | Bright |
| 2 | 5.1 | Bright |
| 3 | 5.1 | Bright |
| 4 | 5.1 | Bright |
| 5 | 5.1 | Bright |
| 6 | 5.1 | Bright |
| 7 | 5.1 | Bright |
| 8 | 5.1 | Bright |
| 9 | 5.1 | Bright |
| 10 | 5.1 | Bright |
| 11 | 5.1 | Bright |
| 12 | 5.1 | Bright |
| 13 | 5.1 | Bright |
| 14 | 5.1 | Bright |
| 15 | 5.1 | Bright |
| 16 | 5.1 | Bright |
| 17 | 5.1 | Bright |
| 18 | 5.1 | Bright |
| 19 | 5.1 | Bright |
| 20 | 5.0 | Bright |
| 21 | 5.0 | Bright |
| 22 | 5.0 | Bright |
| 23 | 5.0 | Bright |
| 24 | 5.0 | Bright |
| 25 | 5.0 | Bright |
| 26 | 5.0 | Bright |
| 27 | 5.0 | Bright |
| 28 | 5.0 | Bright |
| 29 | 5.0 | Bright |
| 30 | 5.0 | Bright |
| 31 | 5.0 | Bright |
Hazard calendar for Ha Long
In May, Ha Long sits inside its pacific typhoon and monsoon season. The full year is below, with each hazard's peak months called out.
Ha Long sits in the Pacific typhoon belt; the season peaks July–October.
Ha Long's monsoon runs May–September, when most of the year's rain falls.
Is May a good time to visit Ha Long?
Our two travel scores rate May for general sightseeing and for beach or pool weather — 0 (poor) to 10 (ideal).
May is a weaker month for outdoor sightseeing in Ha Long.
What to pack for Ha Long in May
From May's temperature range, rain chance, sun and wind — what's worth putting in the bag.
In May, Ha Long sees daytime highs around 30°C and nights near 25°C. Pack light clothes and rain gear. Worth having: sun protection. About 20 days see rain.
Sea temperature near Ha Long in May
The nearest coast averages about 27°C in May — the other half of the beach question. The full-year curve and swim-comfort zones are below.
The sea at the nearest coast (about 32 km away) is warmest in August at about 30°C and coldest in February near 19°C.
It's comfortable for a long swim from Mar 13 to Jan 10 — about 10 months when the water holds above 20°C.
| Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Sea temperature (°C) | 20 | 19 | 20 | 23 | 27 | 29 | 29 | 30 | 29 | 28 | 25 | 22 |
| Comfort | Cool | Cool | Refreshing | Refreshing | Warm | Tropical | Tropical | Tropical | Tropical | Warm | Warm | Refreshing |
| Sea temperature (°C) | Comfort | |
|---|---|---|
| Jan | 20 | Cool |
| Feb | 19 | Cool |
| Mar | 20 | Refreshing |
| Apr | 23 | Refreshing |
| May | 27 | Warm |
| Jun | 29 | Tropical |
| Jul | 29 | Tropical |
| Aug | 30 | Tropical |
| Sep | 29 | Tropical |
| Oct | 28 | Warm |
| Nov | 25 | Warm |
| Dec | 22 | Refreshing |
UV index in Ha Long in May
Clear-sky midday UV in May peaks around 10 (very high — sun protection essential). The full-year curve, shaded by WHO exposure level, is below.
Under clear skies, the midday UV index in Ha Long 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 Ha Long in May
Average fine-particle pollution (PM2.5) through the year — so you can see where May falls, not just the annual average.
Air quality in Ha Long 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 Ha Long?
Ha Long sits at 21.0°N, 107.1°E, 8 m above sea level, in Vietnam. The nearest listed city is Cẩm Phả, 22 km away.
Topography around Ha Long
How much the land rises and falls, and what covers it, within 3, 16 and 80 km of Ha Long.
Within 3 km, the terrain around Ha Long has only modest variations in elevation — a maximum elevation change of 150 m around an average of 9 m above sea level; within 16 km, large variations in elevation — a maximum elevation change of 679 m; within 80 km, very significant variations in elevation — a maximum elevation change of 1,530 m.
The land around Ha Long is covered by water (57%) and artificial surfaces (21%) within 3 km, water (46%) and trees (37%) within 16 km, and trees (42%) and water (42%) 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 Ha Long (20.9505°, 107.0734°, elevation 8 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).