Blue Mountains weather in September

In September, Blue Mountains sees average daytime highs of 17°C and overnight lows near 5°C, with 53 mm of rain across 8.2 wet days and about 11.8 hours of daylight. It is the 8th-warmest and 9th-wettest month of the year here.

Highs climb over the month, from about 15°C in the first days to 18°C by the end. The sky is clear or mostly clear about 46% of the time in September, and the air most often feels dry.

Daylight stretches from about 11 h 18 min at the start of September to 12 h 18 min by month's end. Set against the rest of the year, September is Blue Mountains's 2nd-clearest and 2nd-windiest month. For the whole year in context, see Blue Mountains's year-round climate.

Daytime high: 17°; 8th warmest
Overnight low: 5°; 4th coldest
Rainfall: 53 mm; 8.2 wet days
Daylight: 11 h 48 min; 6:59 AM – 6:47 PM
Cloud cover: 43%; 2nd clearest
Wind: 11 km/h; 2nd windiest
Solar energy: 4.93 kWh/m²
Travel score: 5.8; out of 10

← August Blue Mountains year-round climate October →Best places to visit in September

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

Temperature in September

Average highAverage lowShaded bands: 10–90% of days

Highs climb over the month, from about 15°C in the first days to 18°C by the end.

A typical September day in Blue Mountains reaches about 17°C in the afternoon and slips back to 5°C overnight — a 12°C spread between the day's warmth and the night's chill. On most days the high lands between 12°C and 22°C. Set against its neighbours, September runs about 3°C warmer than August and about 3°C cooler than October.

	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
Avg high (°C)	15	15	15	15	15	16	16	16	16	16	16	16	17	17	17	17	17	17	17	18	18	18	18	18	18	18	18	18	19	19
Avg low (°C)	4	4	4	4	5	5	5	5	5	5	5	5	5	5	5	5	5	5	6	6	6	6	6	6	6	6	6	6	6	6

	Avg high (°C)	Avg low (°C)
1	15	4
2	15	4
3	15	4
4	15	4
5	15	5
6	16	5
7	16	5
8	16	5
9	16	5
10	16	5
11	16	5
12	16	5
13	17	5
14	17	5
15	17	5
16	17	5
17	17	5
18	17	5
19	17	6
20	18	6
21	18	6
22	18	6
23	18	6
24	18	6
25	18	6
26	18	6
27	18	6
28	18	6
29	19	6
30	19	6

How September really feels in Blue Mountains

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

heat index over the day's high

Days feeling ≤ 0°C

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.

Blue Mountains 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.

Month	High / Low (°C)	Rainfall (mm)	Wet days	Daylight (hours)	Travel score
Jan	25° / 14°	126	15.6	14	6.0
Feb	24° / 14°	146	15.4	13.3	5.9
Mar	22° / 12°	115	15.2	12.3	6.0
Apr	19° / 8°	56	9.1	11.2	6.3
May	15° / 6°	48	6.6	10.3	5.3
Jun	13° / 4°	62	7.5	9.8	3.7
Jul	12° / 3°	37	6.3	10	3.6
Aug	14° / 3°	46	6.7	10.7	4.4
Sep	17° / 5°	53	8.2	11.8	5.8
Oct	20° / 8°	75	10.5	12.8	6.3
Nov	22° / 10°	109	13.7	13.7	6.1
Dec	24° / 12°	121	13.4	14.2	6.4

Cloud cover in September

ClearMostly clearPartly cloudyMostly cloudyOvercast

The sky is clear or mostly clear about 46% of the time in September.

Beyond those clear spells, partly cloudy skies cover about 21% of September, with mostly cloudy or overcast conditions the remaining 33%.

	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
Clearer (%)	63	63	64	64	64	64	66	66	67	67	68	68	69	69	70	70	70	69	70	70	70	70	69	69	69	69	68	67	66	66
Cloudier (%)	37	37	36	36	36	36	34	34	33	33	32	32	31	31	30	30	30	31	30	30	30	30	31	31	31	31	32	33	34	34

	Clearer (%)	Cloudier (%)
1	63	37
2	63	37
3	64	36
4	64	36
5	64	36
6	64	36
7	66	34
8	66	34
9	67	33
10	67	33
11	68	32
12	68	32
13	69	31
14	69	31
15	70	30
16	70	30
17	70	30
18	69	31
19	70	30
20	70	30
21	70	30
22	70	30
23	69	31
24	69	31
25	69	31
26	69	31
27	68	32
28	67	33
29	66	34
30	66	34

Chance of precipitation in September

Any precipitation

Blue Mountains gets around 53 mm of rain over 8.2 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 27% and peaks near 29% on the wettest days.

	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
Rain chance (%)	29	29	29	29	29	29	28	28	28	27	27	27	26	26	26	26	26	26	26	26	26	27	27	27	27	27	27	28	28	28

	Rain chance (%)
1	29
2	29
3	29
4	29
5	29
6	29
7	28
8	28
9	28
10	27
11	27
12	27
13	26
14	26
15	26
16	26
17	26
18	26
19	26
20	26
21	26
22	27
23	27
24	27
25	27
26	27
27	27
28	28
29	28
30	28

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 100% of days. It rarely turns muggy — the humid and sticky bands barely register.

	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
Dry (%)	100	100	100	100	100	100	100	100	100	100	100	100	100	100	100	100	100	100	100	100	100	100	100	99	99	99	99	99	99	99
Comfortable (%)	0	0	0	0	0	0	0	0	0	0	0	0	0	0	0	0	0	0	0	0	0	0	0	1	1	1	1	1	1	1

	Dry (%)	Comfortable (%)
1	100	0
2	100	0
3	100	0
4	100	0
5	100	0
6	100	0
7	100	0
8	100	0
9	100	0
10	100	0
11	100	0
12	100	0
13	100	0
14	100	0
15	100	0
16	100	0
17	100	0
18	100	0
19	100	0
20	100	0
21	100	0
22	100	0
23	100	0
24	99	1
25	99	1
26	99	1
27	99	1
28	99	1
29	99	1
30	99	1

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 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
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	11
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

	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	11	calm

Sunrise & sunset in September

DaylightNight

Daylight runs from about 11 h 18 min at the start of September to 12 h 18 min by month's end. The lit band spans sunrise to sunset each day.

Days grow by about 60 minutes over September. Sunrise moves from 7:20 AM to 6:39 AM, and sunset from 6:36 PM to 6:57 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
Daylight (h)	11.3	11.3	11.3	11.4	11.4	11.4	11.5	11.5	11.5	11.6	11.6	11.7	11.7	11.7	11.8	11.8	11.8	11.9	11.9	11.9	12.0	12.0	12.0	12.1	12.1	12.2	12.2	12.2	12.3	12.3
Sunrise (AM)	7:20	7:19	7:18	7:16	7:15	7:14	7:12	7:11	7:09	7:08	7:06	7:05	7:04	7:02	7:01	6:59	6:58	6:56	6:55	6:53	6:52	6:51	6:49	6:48	6:46	6:45	6:43	6:42	6:41	6:39
Sunset (PM)	6:36	6:37	6:38	6:38	6:39	6:40	6:41	6:41	6:42	6:43	6:43	6:44	6:45	6:45	6:46	6:47	6:48	6:48	6:49	6:50	6:50	6:51	6:52	6:52	6:53	6:54	6:55	6:55	6:56	6:57

	Daylight (h)	Sunrise (AM)	Sunset (PM)
1	11.3	7:20	6:36
2	11.3	7:19	6:37
3	11.3	7:18	6:38
4	11.4	7:16	6:38
5	11.4	7:15	6:39
6	11.4	7:14	6:40
7	11.5	7:12	6:41
8	11.5	7:11	6:41
9	11.5	7:09	6:42
10	11.6	7:08	6:43
11	11.6	7:06	6:43
12	11.7	7:05	6:44
13	11.7	7:04	6:45
14	11.7	7:02	6:45
15	11.8	7:01	6:46
16	11.8	6:59	6:47
17	11.8	6:58	6:48
18	11.9	6:56	6:48
19	11.9	6:55	6:49
20	11.9	6:53	6:50
21	12.0	6:52	6:50
22	12.0	6:51	6:51
23	12.0	6:49	6:52
24	12.1	6:48	6:52
25	12.1	6:46	6:53
26	12.2	6:45	6:54
27	12.2	6:43	6:55
28	12.2	6:42	6:55
29	12.3	6:41	6:56
30	12.3	6:39	6:57

Solar energy in September

Daily solar energy (kWh/m²)

Average shortwave solar energy reaching the ground each day in September, about 4.93 kWh/m².

For context, solar energy here swings from a low near 2.4 kWh/m² to a high of 6.58 kWh/m² in December across the year — September's 4.93 kWh/m² falls in the middle.

	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
Solar energy (kWh/m²)	4.2	4.2	4.3	4.3	4.4	4.4	4.5	4.5	4.6	4.7	4.7	4.8	4.8	4.9	4.9	5.0	5.0	5.1	5.1	5.2	5.2	5.2	5.3	5.3	5.3	5.4	5.4	5.4	5.5	5.5
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

	Solar energy (kWh/m²)	Level
1	4.2	Bright
2	4.2	Bright
3	4.3	Bright
4	4.3	Bright
5	4.4	Bright
6	4.4	Bright
7	4.5	Bright
8	4.5	Bright
9	4.6	Bright
10	4.7	Bright
11	4.7	Bright
12	4.8	Bright
13	4.8	Bright
14	4.9	Bright
15	4.9	Bright
16	5.0	Bright
17	5.0	Bright
18	5.1	Bright
19	5.1	Bright
20	5.2	Bright
21	5.2	Bright
22	5.2	Bright
23	5.3	Bright
24	5.3	Bright
25	5.3	Bright
26	5.4	Bright
27	5.4	Bright
28	5.4	Bright
29	5.5	Bright
30	5.5	Bright

Planning a trip in September

Hazard calendar for Blue Mountains

In seasonPeak

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

Blue Mountains's rainy season runs October–March, 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 Blue Mountains?

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

5.8

Sightseeing

8th-best month of the year

1.3

Beach & pool

8th-best month of the year

September is a reasonable time to visit Blue Mountains for sightseeing.

What to pack for Blue Mountains in September

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

In September, Blue Mountains sees daytime highs around 17°C and nights near 5°C. Worth packing: a warm layer, rain gear and sun protection. About 8 days see rain.

a warm layerrain gearsun protection

UV index in Blue Mountains in September

LowModerateHighVery highExtreme

Clear-sky midday UV in September peaks around 6 — enough to warrant sun protection. The full-year curve, shaded by WHO exposure level, is below.

Under clear skies, the midday UV index in Blue Mountains peaks around January 18 at about 13 (extreme) — sunscreen, a hat and midday shade are essential. It bottoms out near June 18 at about 3 (moderate).

The index reaches 3 or more — the level where the WHO recommends sun protection — in 11 months of the year.

	Jan	Feb	Mar	Apr	May	Jun	Jul	Aug	Sep	Oct	Nov	Dec
UV index (midday)	13	12	9	6	4	2	3	4	6	9	10	12
Level	Extreme	Extreme	Very high	High	Moderate	Moderate	Moderate	Moderate	High	Very high	Extreme	Extreme

	UV index (midday)	Level
Jan	13	Extreme
Feb	12	Extreme
Mar	9	Very high
Apr	6	High
May	4	Moderate
Jun	2	Moderate
Jul	3	Moderate
Aug	4	Moderate
Sep	6	High
Oct	9	Very high
Nov	10	Extreme
Dec	12	Extreme

Air quality in Blue Mountains 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 Blue Mountains is worst in December — around 49 µg/m³ PM2.5 (poor), about 12.5× the cleanest month (July, 4 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)	11	5	6	9	14	8	4	5	6	7	21	49
Level	Good	Good	Good	Good	Moderate	Good	Good	Good	Good	Good	Moderate	Poor

	PM2.5 (µg/m³)	Level
Jan	11	Good
Feb	5	Good
Mar	6	Good
Apr	9	Good
May	14	Moderate
Jun	8	Good
Jul	4	Good
Aug	5	Good
Sep	6	Good
Oct	7	Good
Nov	21	Moderate
Dec	49	Poor

Location & terrain

Where is Blue Mountains?

Blue Mountains sits at 33.7°S, 150.3°E, 978 m above sea level, in Australia. The nearest listed city is Katoomba, 2.0 km away.

Topography around Blue Mountains

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

Within 3 km, the terrain around Blue Mountains has large variations in elevation — a maximum elevation change of 696 m around an average of 890 m above sea level; within 16 km, large variations in elevation — a maximum elevation change of 1,002 m; within 80 km, very significant variations in elevation — a maximum elevation change of 1,382 m.

The land around Blue Mountains is covered by trees (91%) within 3 km, trees (92%) within 16 km, and trees (73%) and grassland (21%) within 80 km.

3 km

696 m

trees 91%

16 km

1,002 m

trees 92%

80 km

1,382 m

trees 73%

treesgrasslandartificial surfaceswater

← August Blue Mountains year-round climate October →Best places to visit in September

September weather nearby: Katoomba 2.0 km · Glenmore Park 32 km · Cranebrook 35 km · St Clair 43 km · Mount Druitt 45 km · Quakers Hill 51 km · Blacktown 55 km · Glenwood 56 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

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 Blue Mountains (-33.7133°, 150.3306°, elevation 978 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).

	Avg high (°C)	Avg low (°C)
1	15	4
2	15	4
3	15	4
4	15	4
5	15	5
6	16	5
7	16	5
8	16	5
9	16	5
10	16	5
11	16	5
12	16	5
13	17	5
14	17	5
15	17	5
16	17	5
17	17	5
18	17	5
19	17	6
20	18	6
21	18	6
22	18	6
23	18	6
24	18	6
25	18	6
26	18	6
27	18	6
28	18	6
29	19	6
30	19	6

	Clearer (%)	Cloudier (%)
1	63	37
2	63	37
3	64	36
4	64	36
5	64	36
6	64	36
7	66	34
8	66	34
9	67	33
10	67	33
11	68	32
12	68	32
13	69	31
14	69	31
15	70	30
16	70	30
17	70	30
18	69	31
19	70	30
20	70	30
21	70	30
22	70	30
23	69	31
24	69	31
25	69	31
26	69	31
27	68	32
28	67	33
29	66	34
30	66	34

	Rain chance (%)
1	29
2	29
3	29
4	29
5	29
6	29
7	28
8	28
9	28
10	27
11	27
12	27
13	26
14	26
15	26
16	26
17	26
18	26
19	26
20	26
21	26
22	27
23	27
24	27
25	27
26	27
27	27
28	28
29	28
30	28

	Dry (%)	Comfortable (%)
1	100	0
2	100	0
3	100	0
4	100	0
5	100	0
6	100	0
7	100	0
8	100	0
9	100	0
10	100	0
11	100	0
12	100	0
13	100	0
14	100	0
15	100	0
16	100	0
17	100	0
18	100	0
19	100	0
20	100	0
21	100	0
22	100	0
23	100	0
24	99	1
25	99	1
26	99	1
27	99	1
28	99	1
29	99	1
30	99	1

	Avg high (°C)	Avg low (°C)
1	15	4
2	15	4
3	15	4
4	15	4
5	15	5
6	16	5
7	16	5
8	16	5
9	16	5
10	16	5
11	16	5
12	16	5
13	17	5
14	17	5
15	17	5
16	17	5
17	17	5
18	17	5
19	17	6
20	18	6
21	18	6
22	18	6
23	18	6
24	18	6
25	18	6
26	18	6
27	18	6
28	18	6
29	19	6
30	19	6

	Clearer (%)	Cloudier (%)
1	63	37
2	63	37
3	64	36
4	64	36
5	64	36
6	64	36
7	66	34
8	66	34
9	67	33
10	67	33
11	68	32
12	68	32
13	69	31
14	69	31
15	70	30
16	70	30
17	70	30
18	69	31
19	70	30
20	70	30
21	70	30
22	70	30
23	69	31
24	69	31
25	69	31
26	69	31
27	68	32
28	67	33
29	66	34
30	66	34

	Rain chance (%)
1	29
2	29
3	29
4	29
5	29
6	29
7	28
8	28
9	28
10	27
11	27
12	27
13	26
14	26
15	26
16	26
17	26
18	26
19	26
20	26
21	26
22	27
23	27
24	27
25	27
26	27
27	27
28	28
29	28
30	28

	Dry (%)	Comfortable (%)
1	100	0
2	100	0
3	100	0
4	100	0
5	100	0
6	100	0
7	100	0
8	100	0
9	100	0
10	100	0
11	100	0
12	100	0
13	100	0
14	100	0
15	100	0
16	100	0
17	100	0
18	100	0
19	100	0
20	100	0
21	100	0
22	100	0
23	100	0
24	99	1
25	99	1
26	99	1
27	99	1
28	99	1
29	99	1
30	99	1

	Avg high (°C)	Avg low (°C)
1	15	4
2	15	4
3	15	4
4	15	4
5	15	5
6	16	5
7	16	5
8	16	5
9	16	5
10	16	5
11	16	5
12	16	5
13	17	5
14	17	5
15	17	5
16	17	5
17	17	5
18	17	5
19	17	6
20	18	6
21	18	6
22	18	6
23	18	6
24	18	6
25	18	6
26	18	6
27	18	6
28	18	6
29	19	6
30	19	6

	Clearer (%)	Cloudier (%)
1	63	37
2	63	37
3	64	36
4	64	36
5	64	36
6	64	36
7	66	34
8	66	34
9	67	33
10	67	33
11	68	32
12	68	32
13	69	31
14	69	31
15	70	30
16	70	30
17	70	30
18	69	31
19	70	30
20	70	30
21	70	30
22	70	30
23	69	31
24	69	31
25	69	31
26	69	31
27	68	32
28	67	33
29	66	34
30	66	34

	Rain chance (%)
1	29
2	29
3	29
4	29
5	29
6	29
7	28
8	28
9	28
10	27
11	27
12	27
13	26
14	26
15	26
16	26
17	26
18	26
19	26
20	26
21	26
22	27
23	27
24	27
25	27
26	27
27	27
28	28
29	28
30	28

	Dry (%)	Comfortable (%)
1	100	0
2	100	0
3	100	0
4	100	0
5	100	0
6	100	0
7	100	0
8	100	0
9	100	0
10	100	0
11	100	0
12	100	0
13	100	0
14	100	0
15	100	0
16	100	0
17	100	0
18	100	0
19	100	0
20	100	0
21	100	0
22	100	0
23	100	0
24	99	1
25	99	1
26	99	1
27	99	1
28	99	1
29	99	1
30	99	1