Boyolali weather in September

In September, Boyolali sees average daytime highs of 28°C and overnight lows near 20°C, with 71 mm of rain across 9.6 wet days and about 12 hours of daylight. It is the 6th-warmest and 10th-wettest month of the year here.

Day-to-day highs hold fairly steady near 28°C through the month. The sky is clear or mostly clear about 13% of the time in September, and the air most often feels muggy.

Daylight stretches from about 11 h 54 min at the start of September to 12 h 06 min by month's end. Set against the rest of the year, September is Boyolali's 4th-clearest and 1st-windiest month. For the whole year in context, see Boyolali's year-round climate.

Daytime high
28°
6th warmest
Overnight low
20°
3rd coldest
Rainfall
71 mm
9.6 wet days
Daylight
12 hours
5:33 AM – 5:31 PM
Cloud cover
66%
4th clearest
Wind
6 km/h
1st windiest
Solar energy
5.86 kWh/m²
Travel score
5.7
out of 10

Temperature in September

Average highAverage lowShaded bands: 10–90% of days

Day-to-day highs hold fairly steady near 28°C through the month.

A typical September day in Boyolali reaches about 28°C in the afternoon and slips back to 20°C overnight — a 9°C spread between the day's warmth and the night's chill. On most days the high lands between 27°C and 30°C. Set against its neighbours, September runs on par with August and on par with October.

15°20°25°30°35°151015202530
Avg high (°C)Avg low (°C)
12819
22819
32819
42819
52819
62819
72819
82819
92819
102819
112819
122820
132820
142820
152820
162820
172820
182820
192820
202820
212820
222820
232820
242820
252820
262820
272820
282820
292820
302820

Boyolali weather by month

How September compares with the rest of the year at a glance. September is the 6th-warmest and 10th-wettest month here — the current month is highlighted below.

MonthHigh / Low (°C)Rainfall (mm)Wet daysDaylight (hours)Travel score
Jan28° / 21°44729.212.43.2
Feb28° / 21°45127.412.23.0
Mar29° / 21°40729.312.13.0
Apr29° / 21°28226.711.83.3
May29° / 21°14820.411.74.3
Jun28° / 20°9614.711.65.3
Jul28° / 19°6210.411.66.3
Aug28° / 19°426.811.86.8
Sep28° / 20°719.6125.7
Oct29° / 21°17919.712.24.3
Nov29° / 21°34026.912.33.3
Dec28° / 21°38727.912.43.3

Cloud cover in September

ClearMostly clearPartly cloudyMostly cloudyOvercast

The sky is clear or mostly clear about 13% of the time in September.

Beyond those clear spells, partly cloudy skies cover about 27% of September, with mostly cloudy or overcast conditions the remaining 60%. Skies tend to cloud over as the month goes on.

0%25%50%75%100%151015202530
Clearer (%)Cloudier (%)
14654
24654
34654
44654
54654
64654
74555
84555
94456
104456
114456
124357
134357
144357
154258
164159
174060
184060
193961
203862
213862
223664
233664
243664
253565
263367
273367
283367
293268
303169

Chance of precipitation in September

Any precipitation

Boyolali gets around 71 mm of rain over 9.6 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 33% and peaks near 46% on the wettest days. The odds climb toward the end of the month.

0%20%40%60%151015202530
Rain chance (%)
126
227
327
427
527
627
727
827
927
1027
1128
1228
1329
1429
1530
1631
1732
1833
1934
2035
2136
2237
2338
2439
2540
2641
2743
2844
2945
3046

Humidity in September

DryComfortableHumidMuggyOppressiveMiserable

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

By dew point, September lands in the muggy band about 70% of days. Sticky, muggy-or-worse air turns up on roughly 81% of them.

0%25%50%75%100%151015202530
Comfortable (%)Humid (%)Muggy (%)Oppressive (%)
1224677
2223678
3223678
4223687
5222697
6222697
7222697
8222697
9222697
10122707
11122707
12121708
13121708
14120718
15120709
16119719
171187110
181187011
190177112
200167212
210157213
220147214
230137215
240137116
250127216
260127117
270117118
280117118
290107119
300107119

Wind in September

Winds average 6 km/h in September, the windiest month of the year.

Across September, daily wind ranges from about 6 km/h on the calmest days to 7 km/h at its breeziest. It stays fairly steady from day to day.

0246810151015202530
Wind speed (km/h)Feels
16calm
26calm
36calm
46calm
56calm
66calm
76calm
86calm
96calm
106calm
116calm
126calm
136calm
146calm
156calm
166calm
176calm
186calm
196calm
206calm
216calm
226calm
236calm
247calm
257calm
267calm
277calm
286calm
296calm
306calm

Sunrise & sunset in September

DaylightNight

Daylight runs from about 11 h 54 min at the start of September to 12 h 06 min by month's end. The lit band spans sunrise to sunset each day.

Days grow by about 12 minutes over September. Sunrise moves from 5:42 AM to 5:25 AM, and sunset from 5:33 PM to 5:29 PM.

12 AM4 AM8 AM12 PM4 PM8 PM12 AM151015202530
Daylight (h)Sunrise (AM)Sunset (PM)
111.95:425:33
211.95:415:33
311.95:415:33
411.95:405:33
511.95:405:32
611.95:395:32
711.95:385:32
811.95:385:32
911.95:375:32
1011.95:375:32
1111.95:365:32
1211.95:365:31
1311.95:355:31
1411.95:345:31
1512.05:345:31
1612.05:335:31
1712.05:335:31
1812.05:325:30
1912.05:315:30
2012.05:315:30
2112.05:305:30
2212.05:305:30
2312.05:295:30
2412.05:295:29
2512.05:285:29
2612.05:275:29
2712.05:275:29
2812.05:265:29
2912.15:265:29
3012.15:255:29

Solar energy in September

Daily solar energy (kWh/m²)

Average shortwave solar energy reaching the ground each day in September, about 5.86 kWh/m² — the sunniest month for solar.

For context, solar energy here swings from a low near 4.49 kWh/m² to a high of 5.86 kWh/m² in September across the year — September's 5.86 kWh/m² sits near the top of that range.

0246151015202530
Solar energy (kWh/m²)Level
15.7Bright
25.7Bright
35.7Bright
45.8Bright
55.8Bright
65.8Bright
75.8Bright
85.8Bright
95.8Bright
105.8Bright
115.9Bright
125.9Bright
135.9Bright
145.9Bright
155.9Bright
165.9Bright
175.9Bright
185.9Bright
195.9Bright
205.9Bright
215.9Bright
225.9Bright
235.9Bright
245.9Bright
255.9Bright
265.9Bright
275.9Bright
285.9Bright
295.9Bright
305.9Bright
Planning a trip in September

Hazard calendar for Boyolali

In seasonPeak

None of Boyolali's seasonal hazards are active in September. The full-year calendar below shows when the rainy season, cyclone risk and dust haze do peak.

Boyolali sits in the South Indian Ocean cyclone belt; the season peaks January–March.

Boyolali's rainy season runs November–April, when most of the year's rain falls.

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

Is September a good time to visit Boyolali?

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

5.7
Sightseeing
3rd-best month of the year
6.7
Beach & pool
2nd-best month of the year

September is a reasonable time to visit Boyolali for sightseeing. The water and warmth also suit a beach or pool day.

What to pack for Boyolali in September

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

In September, Boyolali sees daytime highs around 28°C and nights near 20°C. Pack light clothes. Worth having: rain gear and sun protection. About 10 days see rain.

light clothesrain gearsun protection

Sea temperature near Boyolali in September

The nearest coast averages about 25°C in September — the other half of the beach question. The full-year curve and swim-comfort zones are below.

The sea at the nearest coast (about 64 km away) is warmest in March at about 29°C and coldest in August near 25°C.

The water stays above 20°C all year — warm enough for a swim any month.

24°26°28°30°JanFebMarAprMayJunJulAugSepOctNovDecrefreshingwarmtropicalcomfortable to swim
Sea temperature (°C)Comfort
Jan29Tropical
Feb29Tropical
Mar29Tropical
Apr29Tropical
May29Tropical
Jun28Warm
Jul26Warm
Aug25Warm
Sep25Warm
Oct26Warm
Nov28Warm
Dec29Tropical

UV index in Boyolali in September

LowModerateHighVery highExtreme

Clear-sky midday UV in September peaks around 13 (very high — sun protection essential). The full-year curve, shaded by WHO exposure level, is below.

Under clear skies, the midday UV index in Boyolali peaks around March 14 at about 15 (extreme) — sunscreen, a hat and midday shade are essential. It bottoms out near June 14 at about 6 (high).

The index reaches 3 or more — the level where the WHO recommends sun protection — every month of the year.

025710JanFebMarAprMayJunJulAugSepOctNovDecExtremeVery highVery highExtremeExtremeMar 14UV 15Jun 14UV 6
UV index (midday)Level
Jan14Extreme
Feb14Extreme
Mar15Extreme
Apr12Extreme
May8Very high
Jun6High
Jul10Very high
Aug11Extreme
Sep13Extreme
Oct13Extreme
Nov9Very high
Dec11Extreme

Air quality in Boyolali 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 Boyolali is worst in April — around 58 µg/m³ PM2.5 (unhealthy), about 1.7× the cleanest month (September, 34 µg/m³).

Modeled monthly averages (CAMS reanalysis, 2015–2024).

0204060JanFebMarAprMayJunJulAugSepOctNovDecPoorUnhealthyPoorModeratePoorApr 2158 µg/m³Sep 1134 µg/m³
PM2.5 (µg/m³)Level
Jan48Poor
Feb46Poor
Mar54Poor
Apr58Unhealthy
May57Unhealthy
Jun51Poor
Jul42Poor
Aug35Moderate
Sep34Moderate
Oct37Poor
Nov42Poor
Dec42Poor
Location & terrain

Where is Boyolali?

Boyolali sits at 7.5°S, 110.6°E, 438 m above sea level, in Indonesia. The nearest listed city is Karanganom, 13 km away.

Topography around Boyolali

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

Within 3 km, the terrain around Boyolali has significant variations in elevation — a maximum elevation change of 260 m around an average of 440 m above sea level; within 16 km, extreme variations in elevation — a maximum elevation change of 2,558 m; within 80 km, extreme variations in elevation — a maximum elevation change of 3,291 m.

The land around Boyolali is covered by trees (64%) and artificial surfaces (31%) within 3 km, trees (67%) within 16 km, and trees (61%) and cropland (21%) within 80 km.

3 km
260 m
16 km
2,558 m
80 km
3,291 m
treesgrasslandcroplandartificial surfaceswater
September weather nearby: Karanganom 13 km · Delanggu 13 km · Ngemplak 13 km · Gatak 14 km · Kartasura 16 km · Colomadu 17 km · Ceper 18 km · Kebonarun 19 km

Indonesia travel facts

Travel advisory
Level 2
Exercise Increased Caution
Power plugs
Type C / F
230 V · 50 Hz
Prices
≈ 29% of US
price level, 2025
GDP per capita
$5,060
2025
Happiness
5.6 / 10
World Happiness, 2025
Safe drinking water
30%
of population, 2024
Homicide rate
0.3
per 100k, 2022
Road deaths
11.3
per 100k/yr, 2019
Income group
Upper middle
World Bank
English
Low
EF EPI 471
Religion
Muslim 87%Protestant 8%Roman Catholic 3%Hindu 2%

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 Boyolali (-7.5331°, 110.5958°, elevation 438 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).