Mount Isa weather in September

In September, Mount Isa sees average daytime highs of 31°C and overnight lows near 16°C, with 6 mm of rain across 0.9 wet days and about 11.9 hours of daylight. It is the 8th-warmest and 9th-wettest month of the year here.

Highs climb over the month, from about 29°C in the first days to 33°C by the end. The sky is clear or mostly clear about 83% of the time in September, and the air most often feels dry.

Daylight stretches from about 11 h 36 min at the start of September to 12 h 12 min by month's end. Set against the rest of the year, September is Mount Isa's 3rd-clearest and 7th-windiest month. For the whole year in context, see Mount Isa's year-round climate.

Daytime high
31°
8th warmest
Overnight low
16°
5th coldest
Rainfall
6 mm
0.9 wet days
Daylight
11 h 54 min
6:40 AM – 6:33 PM
Cloud cover
17%
3rd clearest
Wind
17 km/h
7th windiest
Solar energy
6.53 kWh/m²
Travel score
5.9
out of 10

Mount Isa is city in Queensland, Australia.

Air quality
Good
PM10 29.5 µg/m³ · 2019
Founded
1923

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

Temperature in September

Average highAverage lowShaded bands: 10–90% of days

Highs climb over the month, from about 29°C in the first days to 33°C by the end.

A typical September day in Mount Isa reaches about 31°C in the afternoon and slips back to 16°C overnight — a 15°C spread between the day's warmth and the night's chill. On most days the high lands between 27°C and 35°C. Set against its neighbours, September runs about 4°C warmer than August and about 3°C cooler than October.

10°20°30°40°151015202530
Avg high (°C)Avg low (°C)
12914
22914
32915
42915
53015
63015
73015
83015
93015
103015
113115
123116
133116
143116
153116
163116
173116
183216
193217
203217
213217
223217
233217
243217
253318
263318
273318
283318
293318
303318

How September really feels in Mount Isa

Once humidity and wind are folded in, September averages 10 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
10
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.

Mount Isa weather by month

How September compares with the rest of the year at a glance. September is the 8th-warmest and 9th-wettest month here — the current month is highlighted below.

MonthHigh / Low (°C)Rainfall (mm)Wet daysDaylight (hours)Travel score
Jan35° / 24°10410.113.12.4
Feb35° / 24°878.912.72.8
Mar34° / 22°614.512.13.5
Apr32° / 19°141.311.55.3
May27° / 15°71118.2
Jun25° / 11°60.810.89.2
Jul25° / 10°20.510.99.4
Aug27° / 12°20.411.38.8
Sep31° / 16°60.911.95.9
Oct34° / 20°121.812.53.8
Nov36° / 22°275132.5
Dec36° / 24°627.513.22.1

Cloud cover in September

ClearMostly clearPartly cloudyMostly cloudyOvercast

The sky is clear or mostly clear about 83% of the time in September.

Beyond those clear spells, partly cloudy skies cover about 9% of September, with mostly cloudy or overcast conditions the remaining 9%.

0%25%50%75%100%151015202530
Clearer (%)Cloudier (%)
1919
2919
3928
4928
5928
6928
7928
8928
9928
10928
11928
12928
13919
14919
15919
16919
17919
189010
199010
20919
21919
22919
23919
24919
25919
26919
27919
28919
29919
30919

Chance of precipitation in September

Any precipitation

Mount Isa gets around 6 mm of rain over 0.9 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 3% and peaks near 4% on the wettest days.

0%10%20%30%151015202530
Rain chance (%)
13
23
33
43
52
62
72
82
92
102
112
122
132
143
153
163
173
183
194
204
214
224
234
244
254
264
274
284
294
304

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 95% of days. It rarely turns muggy — the humid and sticky bands barely register.

0%25%50%75%100%151015202530
Dry (%)Comfortable (%)Humid (%)
19730
29631
39631
49631
59631
69631
79631
89631
99631
109631
119631
129532
139532
149532
159532
169532
179532
189532
199532
209532
219532
229532
239442
249442
259442
269442
279442
289442
299442
309352

Wind in September

Winds average 17 km/h in September.

Across September, daily wind ranges from about 17 km/h on the calmest days to 18 km/h at its breeziest. It stays fairly steady from day to day.

05101520151015202530
Wind speed (km/h)Feels
118light breeze
218light breeze
318light breeze
418light breeze
518light breeze
618light breeze
718light breeze
818light breeze
918light breeze
1018light breeze
1118light breeze
1218light breeze
1318light breeze
1417light breeze
1517light breeze
1617light breeze
1717light breeze
1817light breeze
1917light breeze
2017light breeze
2117light breeze
2217light breeze
2317light breeze
2417light breeze
2517light breeze
2617light breeze
2717light breeze
2817light breeze
2917light breeze
3017light breeze

Sunrise & sunset in September

DaylightNight

Daylight runs from about 11 h 36 min at the start of September to 12 h 12 min by month's end. The lit band spans sunrise to sunset each day.

Days grow by about 36 minutes over September. Sunrise moves from 6:54 AM to 6:26 AM, and sunset from 6:29 PM to 6:36 PM.

12 AM4 AM8 AM12 PM4 PM8 PM12 AM151015202530
Daylight (h)Sunrise (AM)Sunset (PM)
111.66:546:29
211.66:536:29
311.66:526:30
411.66:516:30
511.76:506:30
611.76:506:30
711.76:496:31
811.76:486:31
911.76:476:31
1011.86:466:31
1111.86:456:32
1211.86:446:32
1311.86:436:32
1411.86:426:32
1511.96:416:33
1611.96:406:33
1711.96:396:33
1811.96:386:33
1911.96:376:34
2012.06:366:34
2112.06:356:34
2212.06:346:34
2312.06:336:35
2412.06:326:35
2512.16:316:35
2612.16:306:35
2712.16:296:36
2812.16:286:36
2912.16:276:36
3012.26:266:36

Solar energy in September

Daily solar energy (kWh/m²)

Average shortwave solar energy reaching the ground each day in September, about 6.53 kWh/m².

For context, solar energy here swings from a low near 4.45 kWh/m² to a high of 7.41 kWh/m² in November across the year — September's 6.53 kWh/m² falls in the middle.

0246151015202530
Solar energy (kWh/m²)Level
16.0Intense
26.1Intense
36.1Intense
46.1Intense
56.2Intense
66.2Intense
76.2Intense
86.3Intense
96.3Intense
106.4Intense
116.4Intense
126.5Intense
136.5Intense
146.5Intense
156.6Intense
166.6Intense
176.6Intense
186.7Intense
196.7Intense
206.7Intense
216.7Intense
226.8Intense
236.8Intense
246.8Intense
256.8Intense
266.8Intense
276.9Intense
286.9Intense
296.9Intense
306.9Intense
Planning a trip in September

Is September a good time to visit Mount Isa?

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

5.9
Sightseeing
5th-best month of the year
8.7
Beach & pool
2nd-best month of the year

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

What to pack for Mount Isa in September

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

In September, Mount Isa sees daytime highs around 31°C and nights near 16°C. Pack light clothes and sun protection.

light clothessun protection

UV index in Mount Isa in September

LowModerateHighVery highExtreme

Clear-sky midday UV in September 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 Mount Isa peaks around February 8 at about 16 (extreme) — sunscreen, a hat and midday shade are essential. It bottoms out near June 21 at about 7 (high).

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

025710JanFebMarAprMayJunJulAugSepOctNovDecExtremeVery highHighVery highExtremeFeb 8UV 16Jun 21UV 7
UV index (midday)Level
Jan16Extreme
Feb16Extreme
Mar14Extreme
Apr11Extreme
May8Very high
Jun7High
Jul7High
Aug9Very high
Sep10Extreme
Oct13Extreme
Nov14Extreme
Dec14Extreme

Air quality in Mount Isa 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 Mount Isa is worst in October — around 26 µg/m³ PM2.5 (moderate), about 2.4× the cleanest month (March, 11 µg/m³).

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

0102030JanFebMarAprMayJunJulAugSepOctNovDecModerateGoodModerateOct 1525 µg/m³Mar 1011 µg/m³
PM2.5 (µg/m³)Level
Jan14Moderate
Feb11Good
Mar11Good
Apr17Moderate
May19Moderate
Jun18Moderate
Jul17Moderate
Aug19Moderate
Sep22Moderate
Oct26Moderate
Nov20Moderate
Dec24Moderate
Location & terrain

Where is Mount Isa?

Mount Isa sits at 20.7°S, 139.5°E, 363 m above sea level, in Australia. The nearest listed city is Alice Springs, 666 km away.

Alice SpringsKirwanTownsvilleCairnsPort DouglasAirlie BeachUluruMackay

Topography around Mount Isa

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

Within 3 km, the terrain around Mount Isa has only modest variations in elevation — a maximum elevation change of 243 m around an average of 364 m above sea level; within 16 km, significant variations in elevation — a maximum elevation change of 341 m; within 80 km, significant variations in elevation — a maximum elevation change of 433 m.

The land around Mount Isa is covered by grassland (33%), artificial surfaces (29%) and bare terrain (20%) within 3 km, grassland (80%) within 16 km, and grassland (84%) within 80 km.

3 km
243 m
16 km
341 m
80 km
433 m
treesshrubsgrasslandartificial surfacesbare terrainwater
September weather nearby: Alice Springs 666 km · Kirwan 771 km · Townsville 781 km · Cairns 783 km · Port Douglas 786 km · Airlie Beach 961 km · Uluru 1,005 km · Mackay 1,005 km

Australia travel facts

Travel advisory
Level 1
Exercise Normal Precautions
Power plugs
Type I
230 V · 50 Hz
Prices
≈ 90% of US
price level, 2025
GDP per capita
$65,130
2025
Happiness
6.9 / 10
World Happiness, 2025
Homicide rate
0.9
per 100k, 2023
Road deaths
4.9
per 100k/yr, 2019
Income group
High
World Bank
Religion
none 38%Roman Catholic 20%Protestant 18%other Christian 4%

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 Mount Isa (-20.7252°, 139.4973°, elevation 363 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).