Ljubljana weather in September

In September, Ljubljana sees average daytime highs of 20°C and overnight lows near 11°C, with 125 mm of rain across 11.1 wet days and about 12.3 hours of daylight. It is the 4th-warmest and 1st-wettest month of the year here.

Highs ease over the month, from about 22°C in the first days to 18°C by the end. The sky is clear or mostly clear about 31% of the time in September, and the air most often feels dry.

Daylight stretches from about 13 h 06 min at the start of September to 11 h 30 min by month's end. Set against the rest of the year, September is Ljubljana's 4th-clearest and 9th-windiest month. For the whole year in context, see Ljubljana's year-round climate.

Daytime high
20°
4th warmest
Overnight low
11°
9th coldest
Rainfall
125 mm
11.1 wet days
Daylight
12 h 18 min
5:47 AM – 6:06 PM
Cloud cover
57%
4th clearest
Wind
6 km/h
9th windiest
Solar energy
3.56 kWh/m²
Travel score
6.1
out of 10

Ljubljana is capital city of Slovenia.

Air quality
Elevated
PM2.5 16.2 µg/m³ · 2019
Density
1,662/km²
people per km²
Founded
1144

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 18°C by the end.

A typical September day in Ljubljana reaches about 20°C in the afternoon and slips back to 11°C overnight — a 9°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 5°C warmer than October.

10°15°20°25°30°151015202530
Avg high (°C)Avg low (°C)
12213
22213
32213
42213
52212
62212
72112
82112
92112
102112
112112
122111
132011
142011
152011
162011
172011
182011
191911
201910
211910
221910
231910
241910
251810
261810
271810
28189
29189
30189

How September really feels in Ljubljana

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.

Ljubljana weather by month

How September compares with the rest of the year at a glance. September is the 4th-warmest and 1st-wettest month here — the current month is highlighted below.

MonthHigh / Low (°C)Rainfall (mm)Wet daysSnow daysDaylight (hours)Travel score
Jan / -2°5984.98.90.0
Feb / -2°748.45.1100.4
Mar10° / 7610.13.311.62.5
Apr15° / 9012113.34.2
May19° / 10°10313.5014.75.7
Jun23° / 13°10513.4015.56.4
Jul25° / 15°9511.4015.26.8
Aug25° / 15°11211.10146.8
Sep20° / 11°12511.1012.36.1
Oct15° / 11710.20.510.74.4
Nov / 12111.22.39.21.7
Dec / -1°909.258.50.0

Cloud cover in September

ClearMostly clearPartly cloudyMostly cloudyOvercast

The sky is clear or mostly clear about 31% of the time in September.

Beyond those clear spells, partly cloudy skies cover about 20% of September, with mostly cloudy or overcast conditions the remaining 49%. Skies tend to cloud over as the month goes on.

0%25%50%75%100%151015202530
Clearer (%)Cloudier (%)
15743
25743
35743
45743
55743
65644
75545
85545
95446
105446
115446
125248
135248
145149
155149
164951
174951
184852
194852
204753
214852
224852
234753
244753
254753
264654
274555
284456
294456
304357

Chance of precipitation in September

Any precipitation

Ljubljana gets around 125 mm of rain over 11.1 wet days in September, the wettest month. The line is the day-by-day chance of measurable precipitation.

Day to day, the chance of measurable rain averages around 38% and peaks near 41% on the wettest days.

0%10%20%30%40%50%151015202530
Rain chance (%)
141
241
341
440
540
640
740
840
939
1039
1139
1238
1338
1438
1537
1637
1737
1836
1936
2036
2135
2235
2335
2435
2535
2635
2735
2836
2936
3037

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 63% of days. It rarely turns muggy — the humid and sticky bands barely register.

0%25%50%75%100%151015202530
Dry (%)Comfortable (%)Humid (%)
1423919
2443917
3463816
4473815
5493813
6503812
7513811
8533710
954379
1055378
1156377
1257367
1359356
1461345
1562335
1664324
1766304
1867294
1970273
2071263
2173243
2274233
2376222
2477212
2578202
2678202
2780191
2880191
2981181
3081181

Wind in September

Winds average 6 km/h in September.

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
227calm
237calm
247calm
257calm
267calm
277calm
287calm
297calm
307calm

Sunrise & sunset in September

DaylightNight

Daylight runs from about 13 h 06 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 96 minutes over September. Sunrise moves from 5:27 AM to 6:05 AM, and sunset from 6:36 PM to 5:38 PM.

12 AM4 AM8 AM12 PM4 PM8 PM12 AM151015202530
Daylight (h)Sunrise (AM)Sunset (PM)
113.15:276:36
213.15:296:34
313.05:306:32
413.05:316:30
512.95:326:28
612.95:346:26
712.85:356:24
812.85:366:22
912.75:386:20
1012.75:396:18
1112.65:406:16
1212.55:426:14
1312.55:436:12
1412.45:446:10
1512.45:456:08
1612.35:476:06
1712.35:486:04
1812.25:496:02
1912.25:516:00
2012.15:525:58
2112.05:535:56
2212.05:555:54
2311.95:565:52
2411.95:575:50
2511.85:585:48
2611.86:005:46
2711.76:015:44
2811.76:025:42
2911.66:045:39
3011.56:055:38

Solar energy in September

Daily solar energy (kWh/m²)

Average shortwave solar energy reaching the ground each day in September, about 3.56 kWh/m².

For context, solar energy here swings from a low near 1.03 kWh/m² to a high of 5.91 kWh/m² in July across the year — September's 3.56 kWh/m² falls in the middle.

012345151015202530
Solar energy (kWh/m²)Level
14.3Bright
24.2Bright
34.2Bright
44.1Bright
54.1Bright
64.0Bright
74.0Moderate
83.9Moderate
93.9Moderate
103.8Moderate
113.8Moderate
123.7Moderate
133.7Moderate
143.6Moderate
153.6Moderate
163.5Moderate
173.5Moderate
183.4Moderate
193.4Moderate
203.3Moderate
213.3Moderate
223.2Moderate
233.2Moderate
243.1Moderate
253.1Moderate
263.0Moderate
273.0Moderate
283.0Moderate
292.9Moderate
302.9Moderate
Planning a trip in September

Is September a good time to visit Ljubljana?

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

6.1
Sightseeing
4th-best month of the year
3.2
Beach & pool
4th-best month of the year

September is a reasonable time to visit Ljubljana for sightseeing.

What to pack for Ljubljana in September

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

In September, Ljubljana sees daytime highs around 20°C and nights near 11°C. Worth packing: rain gear. About 11 days see rain.

rain gear

UV index in Ljubljana 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 Ljubljana peaks around July 16 at about 8 (very high) — sunscreen, a hat and midday shade are essential. It bottoms out near January 10 at about 1 (low).

The index reaches 3 or more — the level where the WHO recommends sun protection — in 8 months of the year.

025710JanFebMarAprMayJunJulAugSepOctNovDecLowModerateHighVery highHighModerateLowJul 16UV 8Jan 10UV 1
UV index (midday)Level
Jan1Low
Feb2Moderate
Mar4Moderate
Apr7High
May6High
Jun8Very high
Jul9Very high
Aug8Very high
Sep5High
Oct3Moderate
Nov2Low
Dec1Low

Air quality in Ljubljana 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 Ljubljana is worst in January — around 20 µg/m³ PM2.5 (moderate), and holds fairly steady the rest of the year.

Seasonal pattern from CAMS reanalysis, scaled to Ljubljana's WHO annual average of 16.2 µg/m³.

0102030JanFebMarAprMayJunJulAugSepOctNovDecModerateJan 1920 µg/m³Sep 1513 µg/m³
PM2.5 (µg/m³)Level
Jan20Moderate
Feb18Moderate
Mar20Moderate
Apr19Moderate
May16Moderate
Jun17Moderate
Jul15Moderate
Aug14Moderate
Sep13Moderate
Oct14Moderate
Nov13Moderate
Dec16Moderate
Location & terrain

Where is Ljubljana?

Ljubljana sits at 46.1°N, 14.5°E, 295 m above sea level, in Slovenia. The nearest listed city is Kranj, 24 km away.

KranjPostojnaTrbovljeBledBohinjVelenjeDivačaNovo Mesto

Topography around Ljubljana

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

Within 3 km, the terrain around Ljubljana has only modest variations in elevation — a maximum elevation change of 165 m around an average of 309 m above sea level; within 16 km, large variations in elevation — a maximum elevation change of 847 m; within 80 km, extreme variations in elevation — a maximum elevation change of 2,759 m.

The land around Ljubljana is covered by artificial surfaces (55%) and trees (36%) within 3 km, trees (56%) and grassland (23%) within 16 km, and trees (77%) within 80 km.

3 km
165 m
16 km
847 m
80 km
2,759 m
treesgrasslandcroplandartificial surfaceswater
September weather nearby: Kranj 24 km · Postojna 38 km · Trbovlje 44 km · Bled 46 km · Bohinj 49 km · Velenje 58 km · Divača 58 km · Novo Mesto 58 km

Slovenia travel facts

Travel advisory
Level 1
Exercise Normal Precautions
Power plugs
Type C / F
230 V · 50 Hz
Prices
≈ 63% of US
price level, 2025
GDP per capita
$37,376
2025
Happiness
6.9 / 10
World Happiness, 2025
Safe drinking water
100%
of population, 2024
Homicide rate
0.6
per 100k, 2023
Road deaths
5.1
per 100k/yr, 2019
Income group
High
World Bank
Religion
Catholic 69%atheist 14%Orthodox 4%non-believer/agnostic 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 Ljubljana (46.0511°, 14.5051°, elevation 295 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).