Celje weather in September

In September, Celje sees average daytime highs of 20°C and overnight lows near 11°C, with 103 mm of rain across 11.2 wet days and about 12.3 hours of daylight. It is the 4th-warmest and 3rd-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 30% of the time in September, and the air most often feels dry.

Daylight stretches from about 13 h 12 min at the start of September to 11 h 30 min by month's end. Set against the rest of the year, September is Celje's 4th-clearest and 10th-windiest month. For the whole year in context, see Celje's year-round climate.

Daytime high
20°
4th warmest
Overnight low
11°
9th coldest
Rainfall
103 mm
11.2 wet days
Daylight
12 h 18 min
5:44 AM – 6:03 PM
Cloud cover
59%
4th clearest
Wind
6 km/h
10th windiest
Solar energy
3.51 kWh/m²
Travel score
6.1
out of 10

Celje is city in Slovenia.

Air quality
Good
PM10 27.4 µg/m³ · 2019
Density
1,676/km²
people per km²
Founded
1451

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 Celje 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°20°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
251910
261810
27189
28189
29189
30189

How September really feels in Celje

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.

Celje weather by month

How September compares with the rest of the year at a glance. September is the 4th-warmest and 3rd-wettest month here — the current month is highlighted below.

MonthHigh / Low (°C)Rainfall (mm)Wet daysSnow daysDaylight (hours)Travel score
Jan / -3°417.24.38.80.0
Feb / -2°537.44.3100.4
Mar11° / 639.93.211.62.6
Apr15° / 7611.40.813.34.4
May20° / 10°9513014.75.8
Jun23° / 14°10414015.56.3
Jul25° / 15°10513.3015.26.4
Aug25° / 15°10112.10146.6
Sep20° / 11°10311.2012.36.1
Oct15° / 889.10.310.74.5
Nov / 869.82.39.21.6
Dec / -2°668.94.58.50.0

Cloud cover in September

ClearMostly clearPartly cloudyMostly cloudyOvercast

The sky is clear or mostly clear about 30% of the time in September.

Beyond those clear spells, partly cloudy skies cover about 19% of September, with mostly cloudy or overcast conditions the remaining 51%.

0%25%50%75%100%151015202530
Clearer (%)Cloudier (%)
15347
25347
35347
45347
55248
65248
75248
85248
95050
105050
115050
125050
134951
144951
154852
164852
174852
184753
194753
204654
214753
224753
234753
244753
254654
264654
274654
284753
294555
304555

Chance of precipitation in September

Any precipitation

Celje gets around 103 mm of rain over 11.2 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 37% and peaks near 41% on the wettest days. The odds ease toward the end of the month.

0%10%20%30%40%50%151015202530
Rain chance (%)
141
241
341
441
541
641
740
840
940
1040
1140
1239
1339
1439
1538
1638
1737
1837
1937
2036
2136
2235
2334
2434
2533
2633
2732
2832
2932
3032

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 64% of days. It rarely turns muggy — the humid and sticky bands barely register.

0%25%50%75%100%151015202530
Dry (%)Comfortable (%)Humid (%)Muggy (%)
14437181
24637170
34837150
44937140
55037130
65237110
75237110
85337100
9543790
10563680
11573670
12573670
13593560
14613450
15623350
16643240
17653140
18672940
19692830
20712630
21722530
22752320
23762220
24772120
25792010
26801910
27811810
28821710
29821710
30841600

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
226calm
236calm
246calm
256calm
266calm
276calm
286calm
297calm
307calm

Sunrise & sunset in September

DaylightNight

Daylight runs from about 13 h 12 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 102 minutes over September. Sunrise moves from 5:24 AM to 6:02 AM, and sunset from 6:33 PM to 5:34 PM.

12 AM4 AM8 AM12 PM4 PM8 PM12 AM151015202530
Daylight (h)Sunrise (AM)Sunset (PM)
113.25:246:33
213.15:256:31
313.05:276:29
413.05:286:27
512.95:296:25
612.95:316:23
712.85:326:21
812.85:336:19
912.75:346:17
1012.75:366:15
1112.65:376:13
1212.55:386:11
1312.55:406:09
1412.45:416:07
1512.45:426:05
1612.35:446:03
1712.35:456:01
1812.25:465:59
1912.25:485:57
2012.15:495:55
2112.05:505:53
2212.05:515:51
2311.95:535:49
2411.95:545:47
2511.85:555:45
2611.85:575:42
2711.75:585:40
2811.65:595:38
2911.66:015:36
3011.56:025:34

Solar energy in September

Daily solar energy (kWh/m²)

Average shortwave solar energy reaching the ground each day in September, about 3.51 kWh/m².

For context, solar energy here swings from a low near 1.08 kWh/m² to a high of 5.72 kWh/m² in June across the year — September's 3.51 kWh/m² falls in the middle.

012345151015202530
Solar energy (kWh/m²)Level
14.2Bright
24.1Bright
34.1Bright
44.0Bright
54.0Moderate
63.9Moderate
73.9Moderate
83.9Moderate
93.8Moderate
103.8Moderate
113.7Moderate
123.7Moderate
133.6Moderate
143.6Moderate
153.5Moderate
163.5Moderate
173.4Moderate
183.4Moderate
193.4Moderate
203.3Moderate
213.3Moderate
223.2Moderate
233.2Moderate
243.1Moderate
253.1Moderate
263.1Moderate
273.0Moderate
283.0Moderate
292.9Moderate
302.9Moderate
Planning a trip in September

Is September a good time to visit Celje?

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 Celje for sightseeing.

What to pack for Celje in September

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

In September, Celje 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 Celje 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 Celje peaks around July 15 at about 8 (very high) — sunscreen, a hat and midday shade are essential. It bottoms out near January 1 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 15UV 8Jan 1UV 1
UV index (midday)Level
Jan1Low
Feb2Low
Mar4Moderate
Apr7High
May7High
Jun8Very high
Jul8Very high
Aug7Very high
Sep5High
Oct3Moderate
Nov2Low
Dec1Low

Air quality in Celje 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 Celje is worst in April — around 17 µg/m³ PM2.5 (moderate), and holds fairly steady the rest of the year.

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

01020JanFebMarAprMayJunJulAugSepOctNovDecModerateGoodModerateApr 917 µg/m³Sep 2012 µg/m³
PM2.5 (µg/m³)Level
Jan16Moderate
Feb15Moderate
Mar17Moderate
Apr17Moderate
May15Moderate
Jun15Moderate
Jul14Moderate
Aug13Moderate
Sep12Good
Oct12Good
Nov12Good
Dec14Moderate
Location & terrain

Where is Celje?

Celje sits at 46.2°N, 15.3°E, 240 m above sea level, in Slovenia. The nearest listed city is Velenje, 18 km away.

VelenjeTrbovljeMariborNovo MestoPtujŽumberakSamoborZaprešić

Topography around Celje

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

Within 3 km, the terrain around Celje has significant variations in elevation — a maximum elevation change of 368 m around an average of 283 m above sea level; within 16 km, large variations in elevation — a maximum elevation change of 915 m; within 80 km, very significant variations in elevation — a maximum elevation change of 2,391 m.

The land around Celje is covered by trees (42%), artificial surfaces (25%) and grassland (24%) within 3 km, trees (62%) and grassland (27%) within 16 km, and trees (70%) within 80 km.

3 km
368 m
16 km
915 m
80 km
2,391 m
treesgrasslandcroplandartificial surfaceswater
September weather nearby: Velenje 18 km · Trbovlje 18 km · Maribor 47 km · Novo Mesto 48 km · Ptuj 51 km · Žumberak 53 km · Samobor 59 km · Zaprešić 59 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 Celje (46.2309°, 15.2604°, elevation 240 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).