Hainan weather in September

In September, Hainan sees average daytime highs of 20°C and overnight lows near 8°C, with 73 mm of rain across 9.1 wet days and about 12.4 hours of daylight. It is the 5th-warmest and 4th-wettest month of the year here.

Highs ease over the month, from about 22°C in the first days to 17°C by the end. The sky is clear or mostly clear about 40% of the time in September, and the air most often feels dry.

Daylight stretches from about 13 h 12 min at the start of September to 11 h 30 min by month's end. Set against the rest of the year, September is Hainan's 6th-clearest and 6th-windiest month. For the whole year in context, see Hainan's year-round climate.

Daytime high
20°
5th warmest
Overnight low
9th coldest
Rainfall
73 mm
9.1 wet days
Daylight
12 h 18 min
5:16 AM – 5:36 PM
Cloud cover
51%
6th clearest
Wind
11 km/h
6th windiest
Solar energy
4.05 kWh/m²
Travel score
6.4
out of 10
Air quality
Elevated
PM2.5 25 µg/m³ · 2018

Air quality: WHO Ambient Air Quality Database. Density & description: Wikidata (CC0), GeoNames.

Temperature in September

Average highAverage lowShaded bands: 10–90% of days

Highs ease over the month, from about 22°C in the first days to 17°C by the end.

A typical September day in Hainan reaches about 20°C in the afternoon and slips back to 8°C overnight — a 11°C spread between the day's warmth and the night's chill. On most days the high lands between 15°C and 25°C. Set against its neighbours, September runs about 5°C cooler than August and about 9°C warmer than October.

10°20°30°151015202530
Avg high (°C)Avg low (°C)
12312
22212
32212
42212
52211
62211
72111
82110
92110
102110
112110
12209
13209
14209
15208
16208
17198
18198
19197
20197
21197
22187
23186
24186
25186
26176
27175
28175
29165
30164

How September really feels in Hainan

Once humidity and wind are folded in, September 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.

Days feeling ≥ 32°C
0
heat index over the day's high
Days feeling ≤ C
0
wind chill below the day's low

September sits comfortably in between — no days that feel dangerously hot or drop to a hard freeze once humidity and wind are folded in.

Hainan weather by month

How September compares with the rest of the year at a glance. September is the 5th-warmest and 4th-wettest month here — the current month is highlighted below.

MonthHigh / Low (°C)Rainfall (mm)Wet daysSnow daysDaylight (hours)Travel score
Jan-15° / -26°41.11.68.70.0
Feb-9° / -22°61.61.9100.0
Mar / -11°163.63.311.60.1
Apr12° / 335.61.213.33.2
May20° / 629.90.114.86.2
Jun25° / 15°10113.3015.66.1
Jul27° / 18°16214.7015.35.8
Aug25° / 16°14313.60146.2
Sep20° / 739.1012.46.4
Oct10° / -0°376.90.910.62.7
Nov-3° / -12°143.22.99.10.0
Dec-13° / -23°82.63.48.30.0

Cloud cover in September

ClearMostly clearPartly cloudyMostly cloudyOvercast

The sky is clear or mostly clear about 40% of the time in September.

Beyond those clear spells, partly cloudy skies cover about 17% of September, with mostly cloudy or overcast conditions the remaining 43%. Skies tend to open up as the month goes on.

0%25%50%75%100%151015202530
Clearer (%)Cloudier (%)
15149
25248
35248
45347
55446
65446
75545
85644
95644
105743
115743
125842
135842
145941
155941
165941
175941
185941
195941
206040
216040
226040
235941
245941
255941
265842
275842
285743
295743
305743

Chance of precipitation in September

Any precipitation

Hainan gets around 73 mm of rain over 9.1 wet days in September. The line is the day-by-day chance of measurable precipitation.

Day to day, the chance of measurable rain averages around 31% and peaks near 40% on the wettest days. The odds ease toward the end of the month.

0%10%20%30%40%50%151015202530
Rain chance (%)
140
240
339
438
537
637
736
835
934
1033
1132
1231
1330
1429
1528
1628
1727
1827
1927
2027
2127
2227
2327
2427
2527
2628
2728
2828
2928
3028

Humidity in September

DryComfortableHumidMuggyOppressiveMiserable

Most of September feels dry — the stacked bands show each day's mix of comfort levels, read off the dew point.

By dew point, September lands in the dry band about 80% of days. It rarely turns muggy — the humid and sticky bands barely register.

0%25%50%75%100%151015202530
Dry (%)Comfortable (%)Humid (%)Muggy (%)
14425265
24725235
35124214
45523184
55822164
66122143
76421123
86820102
9711982
10741871
11771751
12791641
13811531
14841420
15851320
16871210
17881110
18891010
1990910
2091810
2193700
2294600
2395500
2495500
2596400
2696400
2797300
2897300
2998200
3098200

Wind in September

Winds average 11 km/h in September.

Across September, daily wind ranges from about 11 km/h on the calmest days to 12 km/h at its breeziest. It stays fairly steady from day to day.

051015151015202530
Wind speed (km/h)Feels
111calm
211calm
311calm
411calm
511calm
611calm
711calm
811calm
911calm
1011calm
1111calm
1211calm
1311calm
1412calm
1512calm
1612calm
1712calm
1812calm
1912calm
2012calm
2112calm
2212calm
2312calm
2412calm
2512calm
2612calm
2712calm
2812calm
2912calm
3012light breeze

Sunrise & sunset in September

DaylightNight

Daylight runs from about 13 h 12 min at the start of September to 11 h 30 min by month's end. The lit band spans sunrise to sunset each day.

Days shrink by about 102 minutes over September. Sunrise moves from 4:56 AM to 5:36 AM, and sunset from 6:08 PM to 5:07 PM.

12 AM4 AM8 AM12 PM4 PM8 PM12 AM151015202530
Daylight (h)Sunrise (AM)Sunset (PM)
113.24:566:08
213.14:576:06
313.14:596:04
413.05:006:02
513.05:015:59
612.95:035:57
712.95:045:55
812.85:055:53
912.75:075:51
1012.75:085:49
1112.65:105:47
1212.65:115:45
1312.55:125:43
1412.55:145:41
1512.45:155:39
1612.35:165:36
1712.35:185:34
1812.25:195:32
1912.25:205:30
2012.15:225:28
2112.05:235:26
2212.05:255:24
2311.95:265:22
2411.95:275:20
2511.85:295:17
2611.85:305:15
2711.75:325:13
2811.65:335:11
2911.65:345:09
3011.55:365:07

Solar energy in September

Daily solar energy (kWh/m²)

Average shortwave solar energy reaching the ground each day in September, about 4.05 kWh/m².

For context, solar energy here swings from a low near 1.53 kWh/m² to a high of 5.78 kWh/m² in May across the year — September's 4.05 kWh/m² falls in the middle.

012345151015202530
Solar energy (kWh/m²)Level
14.4Bright
24.4Bright
34.3Bright
44.3Bright
54.3Bright
64.3Bright
74.3Bright
84.3Bright
94.2Bright
104.2Bright
114.2Bright
124.2Bright
134.2Bright
144.1Bright
154.1Bright
164.1Bright
174.0Bright
184.0Bright
194.0Moderate
203.9Moderate
213.9Moderate
223.8Moderate
233.8Moderate
243.8Moderate
253.7Moderate
263.7Moderate
273.6Moderate
283.6Moderate
293.5Moderate
303.5Moderate
Planning a trip in September

Hazard calendar for Hainan

In seasonPeak

In September, Hainan sits inside its rainy season season. The full year is below, with each hazard's peak months called out.

Hainan's rainy season runs June–September, when most of the year's rain falls.

Rainy season
Jan
Feb
Mar
Apr
May
Jun
Jul
Aug
Sep
Oct
Nov
Dec

Is September a good time to visit Hainan?

Our two travel scores rate September for general sightseeing and for beach or pool weather — 0 (poor) to 10 (ideal).

6.4
Sightseeing
1st-best month of the year
3.1
Beach & pool
5th-best month of the year

September is a reasonable time to visit Hainan for sightseeing.

What to pack for Hainan in September

From September's temperature range, rain chance, sun and wind — what's worth putting in the bag.

In September, Hainan sees daytime highs around 20°C and nights near 8°C. Worth packing: rain gear. About 9 days see rain.

rain gear

UV index in Hainan in September

LowModerateHighVery highExtreme

Clear-sky midday UV in September peaks around 5 — enough to warrant sun protection. The full-year curve, shaded by WHO exposure level, is below.

Under clear skies, the midday UV index in Hainan peaks around August 17 at about 7 (high) — sunscreen and a hat are worth it in the middle of the day. It bottoms out near December 19 at about 1 (low).

The index reaches 3 or more — the level where the WHO recommends sun protection — in 6 months of the year.

025710JanFebMarAprMayJunJulAugSepOctNovDecLowModerateHighHighModerateLowAug 17UV 7Dec 19UV 1
UV index (midday)Level
Jan1Low
Feb1Low
Mar3Moderate
Apr4Moderate
May5High
Jun6High
Jul5Moderate
Aug7Very high
Sep5Moderate
Oct2Moderate
Nov1Low
Dec1Low

Air quality in Hainan in September

GoodModeratePoorUnhealthyVery unhealthy

Average fine-particle pollution (PM2.5) through the year — so you can see where September falls, not just the annual average.

Air quality in Hainan is worst in March — around 37 µg/m³ PM2.5 (poor), about 2.3× the cleanest month (August, 16 µg/m³).

Seasonal pattern from CAMS reanalysis, scaled to Hainan's WHO annual average of 25 µg/m³.

010203040JanFebMarAprMayJunJulAugSepOctNovDecModerateModerateMar 1636 µg/m³Aug 2016 µg/m³
PM2.5 (µg/m³)Level
Jan31Moderate
Feb31Moderate
Mar37Poor
Apr30Moderate
May21Moderate
Jun19Moderate
Jul20Moderate
Aug16Moderate
Sep17Moderate
Oct22Moderate
Nov28Moderate
Dec27Moderate
Location & terrain

Where is Hainan?

Hainan sits at 47.2°N, 127.0°E, 0 m above sea level, in China. The nearest listed city is Harbin, 167 km away.

RaychikhinskBlagoveshchenskChigiriBelogorskSvobodnyyBirobidzhanNamyang-nodongjagu

Topography around Hainan

How much the land rises and falls, and what covers it, within 3, 16 and 80 km of Hainan.

Within 3 km, the terrain around Hainan has only modest variations in elevation — a maximum elevation change of 73 m around an average of 214 m above sea level; within 16 km, only modest variations in elevation — a maximum elevation change of 91 m; within 80 km, significant variations in elevation — a maximum elevation change of 538 m.

The land around Hainan is covered by cropland (87%) within 3 km, cropland (89%) within 16 km, and cropland (82%) within 80 km.

3 km
73 m
16 km
91 m
80 km
538 m
treesgrasslandcroplandartificial surfaceswater
September weather nearby: Harbin 167 km · Raychikhinsk 336 km · Blagoveshchensk 341 km · Chigiri 347 km · Belogorsk 424 km · Svobodnyy 468 km · Birobidzhan 475 km · Namyang-nodongjagu 526 km

China travel facts

Travel advisory
Level 2
Exercise Increased Caution
Power plugs
Type A / I
220 V · 50 Hz
Prices
≈ 47% of US
price level, 2025
GDP per capita
$13,862
2025
Happiness
6.1 / 10
World Happiness, 2025
Homicide rate
0.5
per 100k, 2020
Road deaths
17.4
per 100k/yr, 2019
Income group
Upper middle
World Bank
English
Low
EF EPI 464
Religion
unaffiliated 52%folk religion 22%Buddhist 18%Christian 5%

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 Hainan (47.2322°, 126.9809°, elevation 0 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. 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).