Kertosono weather in September

In September, Kertosono sees average daytime highs of 33°C and overnight lows near 22°C, with 14 mm of rain across 2.1 wet days and about 12 hours of daylight. It is the 3rd-warmest and 11th-wettest month of the year here.

Day-to-day highs hold fairly steady near 33°C through the month. The sky is clear or mostly clear about 39% 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 Kertosono's 3rd-clearest and 1st-windiest month. For the whole year in context, see Kertosono's year-round climate.

Daytime high
33°
3rd warmest
Overnight low
22°
3rd coldest
Rainfall
14 mm
2.1 wet days
Daylight
12 hours
5:27 AM – 5:25 PM
Cloud cover
51%
3rd clearest
Wind
7 km/h
1st windiest
Solar energy
6.29 kWh/m²
Travel score
4.3
out of 10

Temperature in September

Average highAverage lowShaded bands: 10–90% of days

Day-to-day highs hold fairly steady near 33°C through the month.

A typical September day in Kertosono reaches about 33°C in the afternoon and slips back to 22°C overnight — a 11°C spread between the day's warmth and the night's chill. On most days the high lands between 31°C and 34°C. Set against its neighbours, September runs about 1°C warmer than August and on par with October.

20°25°30°35°151015202530
Avg high (°C)Avg low (°C)
13222
23222
33222
43222
53222
63222
73222
83322
93322
103322
113322
123322
133322
143322
153322
163322
173322
183322
193322
203322
213322
223322
233323
243323
253323
263323
273323
283323
293323
303323

How September really feels in Kertosono

Once humidity and wind are folded in, September averages 30 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
30
heat index over the day's high
Days feeling ≤ C
0
wind chill below the day's low

The story in September is heat — humidity pushes the afternoon "feels like" well above the raw temperature.

Kertosono weather by month

How September compares with the rest of the year at a glance. September is the 3rd-warmest and 11th-wettest month here — the current month is highlighted below.

MonthHigh / Low (°C)Rainfall (mm)Wet daysDaylight (hours)Travel score
Jan31° / 24°3792912.42.4
Feb31° / 24°36827.312.22.3
Mar31° / 24°31828.212.12.4
Apr31° / 24°18122.711.82.9
May31° / 23°7812.511.74.1
Jun31° / 23°356.811.64.7
Jul31° / 22°153.311.65.1
Aug32° / 22°51.211.85.0
Sep33° / 22°142.1124.3
Oct33° / 23°618.712.23.4
Nov33° / 24°1681912.32.6
Dec32° / 24°32126.212.42.5

Cloud cover in September

ClearMostly clearPartly cloudyMostly cloudyOvercast

The sky is clear or mostly clear about 39% of the time in September.

Beyond those clear spells, partly cloudy skies cover about 23% of September, with mostly cloudy or overcast conditions the remaining 38%. Skies tend to cloud over as the month goes on.

0%25%50%75%100%151015202530
Clearer (%)Cloudier (%)
16733
26733
36634
46634
56634
66634
76634
86634
96535
106535
116535
126436
136436
146337
156337
166238
176238
186139
196139
206040
216040
225941
235941
245842
255743
265743
275743
285644
295545
305545

Chance of precipitation in September

Any precipitation

Kertosono gets around 14 mm of rain over 2.1 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 7% and peaks near 13% on the wettest days. The odds climb toward the end of the month.

0%10%20%30%151015202530
Rain chance (%)
15
25
35
45
55
65
75
85
95
105
115
125
135
146
156
166
177
187
198
208
219
229
2310
2410
2511
2611
2712
2812
2913
3013

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 68% of days. Sticky, muggy-or-worse air turns up on roughly 93% of them.

0%25%50%75%100%151015202530
Humid (%)Muggy (%)Oppressive (%)Miserable (%)
1970210
21069210
31069210
41069210
51070200
61070200
71070200
81070200
9971200
10971200
11971200
12971200
13872200
14871210
15771220
16771220
17670231
18669241
19569251
20568261
21469261
22468271
23467281
24366292
25365302
26363322
27362332
28361342
29360352
30359362

Wind in September

Winds average 7 km/h in September, the windiest month of the year.

Across September, daily wind ranges from about 7 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
17calm
27calm
37calm
47calm
57calm
67calm
77calm
87calm
97calm
107calm
117calm
127calm
137calm
147calm
157calm
167calm
177calm
187calm
197calm
207calm
217calm
227calm
237calm
247calm
257calm
267calm
277calm
287calm
297calm
307calm

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 5:36 AM to 5:19 AM, and sunset from 5:27 PM to 5:23 PM.

12 AM4 AM8 AM12 PM4 PM8 PM12 AM151015202530
Daylight (h)Sunrise (AM)Sunset (PM)
111.95:365:27
211.95:355:27
311.95:355:27
411.95:345:27
511.95:345:26
611.95:335:26
711.95:325:26
811.95:325:26
911.95:315:26
1011.95:315:26
1111.95:305:25
1211.95:295:25
1311.95:295:25
1411.95:285:25
1512.05:285:25
1612.05:275:25
1712.05:275:25
1812.05:265:24
1912.05:255:24
2012.05:255:24
2112.05:245:24
2212.05:245:24
2312.05:235:24
2412.05:225:23
2512.05:225:23
2612.05:215:23
2712.05:215:23
2812.05:205:23
2912.15:205:23
3012.15:195:23

Solar energy in September

Daily solar energy (kWh/m²)

Average shortwave solar energy reaching the ground each day in September, about 6.29 kWh/m² — the sunniest month for solar.

For context, solar energy here swings from a low near 4.63 kWh/m² to a high of 6.29 kWh/m² in September across the year — September's 6.29 kWh/m² sits near the top of that range.

0246151015202530
Solar energy (kWh/m²)Level
16.1Intense
26.1Intense
36.1Intense
46.1Intense
56.1Intense
66.2Intense
76.2Intense
86.2Intense
96.2Intense
106.2Intense
116.3Intense
126.3Intense
136.3Intense
146.3Intense
156.3Intense
166.3Intense
176.3Intense
186.3Intense
196.3Intense
206.3Intense
216.3Intense
226.3Intense
236.3Intense
246.3Intense
256.3Intense
266.3Intense
276.3Intense
286.3Intense
296.3Intense
306.3Intense
Planning a trip in September

Hazard calendar for Kertosono

In seasonPeak

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

Kertosono's monsoon runs December–April, when most of the year's rain falls.

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

Is September a good time to visit Kertosono?

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

4.3
Sightseeing
4th-best month of the year
7.4
Beach & pool
3rd-best month of the year

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

What to pack for Kertosono in September

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

In September, Kertosono sees daytime highs around 33°C and nights near 22°C. Pack light clothes and sun protection.

light clothessun protection

UV index in Kertosono 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 Kertosono peaks around March 18 at about 13 (extreme) — sunscreen, a hat and midday shade are essential. It bottoms out near June 14 at about 7 (very high).

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

025710JanFebMarAprMayJunJulAugSepOctNovDecExtremeVery highExtremeExtremeMar 18UV 13Jun 14UV 7
UV index (midday)Level
Jan13Extreme
Feb11Extreme
Mar13Extreme
Apr11Extreme
May9Very high
Jun7High
Jul9Very high
Aug11Extreme
Sep13Extreme
Oct12Extreme
Nov10Very high
Dec12Extreme

Air quality in Kertosono 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 Kertosono is worst in May — around 64 µg/m³ PM2.5 (unhealthy), and holds fairly steady the rest of the year.

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

020406080JanFebMarAprMayJunJulAugSepOctNovDecPoorUnhealthyPoorMay 1764 µg/m³Dec 2343 µg/m³
PM2.5 (µg/m³)Level
Jan44Poor
Feb45Poor
Mar53Poor
Apr59Unhealthy
May64Unhealthy
Jun60Unhealthy
Jul54Poor
Aug48Poor
Sep47Poor
Oct49Poor
Nov48Poor
Dec43Poor
Location & terrain

Where is Kertosono?

Kertosono sits at 7.6°S, 112.1°E, 43 m above sea level, in Indonesia. The nearest listed city is Diwek, 14 km away.

Topography around Kertosono

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

Within 3 km, the terrain around Kertosono has only modest variations in elevation — a maximum elevation change of 13 m around an average of 42 m above sea level; within 16 km, only modest variations in elevation — a maximum elevation change of 248 m; within 80 km, extreme variations in elevation — a maximum elevation change of 3,305 m.

The land around Kertosono is covered by cropland (52%), trees (23%) and artificial surfaces (22%) within 3 km, cropland (55%) and trees (28%) within 16 km, and trees (49%) and cropland (37%) within 80 km.

3 km
13 m
16 km
248 m
80 km
3,305 m
treesgrasslandcroplandartificial surfaceswater
September weather nearby: Diwek 14 km · Jombang 15 km · Ngoro 21 km · Gampengrejo 21 km · Nganjuk 22 km · Pare 23 km · Kediri 28 km · Mojoagung 28 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 Kertosono (-7.5833°, 112.1°, elevation 43 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).