Rijeka weather in September

In September, Rijeka sees average daytime highs of 20°C and overnight lows near 14°C, with 177 mm of rain across 11.8 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 23°C in the first days to 18°C by the end. The sky is clear or mostly clear about 40% 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 36 min by month's end. Set against the rest of the year, September is Rijeka's 4th-clearest and 7th-windiest month. For the whole year in context, see Rijeka's year-round climate.

Daytime high
20°
4th warmest
Overnight low
14°
9th coldest
Rainfall
177 mm
11.8 wet days
Daylight
12 h 18 min
5:47 AM – 6:06 PM
Cloud cover
50%
4th clearest
Wind
9 km/h
7th windiest
Solar energy
3.9 kWh/m²
Travel score
6.2
out of 10
Air quality
Moderate
PM2.5 10.6 µg/m³ · 2019

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 23°C in the first days to 18°C by the end.

A typical September day in Rijeka reaches about 20°C in the afternoon and slips back to 14°C overnight — a 7°C spread between the day's warmth and the night's chill. On most days the high lands between 16°C and 24°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)
12316
22316
32316
42215
52215
62215
72215
82215
92215
102115
112114
122114
132114
142114
152114
162014
172014
182013
192013
202013
212013
221913
231913
241913
251913
261912
271912
281812
291812
301812

How September really feels in Rijeka

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.

Rijeka 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 / 12311.54.28.90.2
Feb / 12810.74.710.10.7
Mar10° / 12311.63.211.62.3
Apr14° / 114130.913.23.8
May19° / 12°12013.70.114.65.5
Jun23° / 16°9412015.46.7
Jul25° / 18°7710015.17.2
Aug25° / 18°908.8013.97.3
Sep20° / 14°17711.8012.36.2
Oct16° / 10°20813.40.510.74.5
Nov11° / 22314.429.32.2
Dec / 16912.248.60.6

Cloud cover in September

ClearMostly clearPartly cloudyMostly cloudyOvercast

The sky is clear or mostly clear about 40% of the time in September.

Beyond those clear spells, partly cloudy skies cover about 18% of September, with mostly cloudy or overcast conditions the remaining 42%. Skies tend to cloud over as the month goes on.

0%25%50%75%100%151015202530
Clearer (%)Cloudier (%)
16634
26535
36535
46436
56436
66337
76436
86337
96337
106238
116139
126139
136040
146040
155941
165842
175743
185743
195644
205545
215446
225446
235446
245347
255248
265149
275050
285050
294951
304951

Chance of precipitation in September

Any precipitation

Rijeka gets around 177 mm of rain over 11.8 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 40% and peaks near 44% on the wettest days. The odds climb toward the end of the month.

0%10%20%30%40%50%151015202530
Rain chance (%)
134
235
335
436
537
638
738
839
940
1040
1141
1241
1341
1441
1541
1641
1741
1841
1941
2041
2141
2241
2341
2441
2541
2642
2742
2843
2944
3044

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 48% of days. It rarely turns muggy — the humid and sticky bands barely register.

0%25%50%75%100%151015202530
Dry (%)Comfortable (%)Humid (%)Muggy (%)
13235303
23336282
33437272
43637262
53638241
63738231
73839231
83839221
93940211
103940201
114040201
124140191
134239181
144339170
154538170
164637160
174837150
185135140
195334130
205533120
215732110
225732110
235931100
24603190
25623080
26623080
27633070
28633070
29642970
30652960

Wind in September

Winds average 9 km/h in September.

Across September, daily wind ranges from about 9 km/h on the calmest days to 9 km/h at its breeziest. It stays fairly steady from day to day.

051015151015202530
Wind speed (km/h)Feels
19calm
29calm
39calm
49calm
59calm
69calm
79calm
89calm
99calm
109calm
119calm
129calm
139calm
149calm
159calm
169calm
179calm
189calm
199calm
209calm
219calm
229calm
239calm
249calm
259calm
269calm
279calm
289calm
299calm
309calm

Sunrise & sunset in September

DaylightNight

Daylight runs from about 13 h 06 min at the start of September to 11 h 36 min by month's end. The lit band spans sunrise to sunset each day.

Days shrink by about 90 minutes over September. Sunrise moves from 5:28 AM to 6:05 AM, and sunset from 6:35 PM to 5:38 PM.

12 AM4 AM8 AM12 PM4 PM8 PM12 AM151015202530
Daylight (h)Sunrise (AM)Sunset (PM)
113.15:286:35
213.15:306:34
313.05:316:32
413.05:326:30
512.95:336:28
612.95:356:26
712.85:366:24
812.75:376:22
912.75:386:20
1012.65:406:18
1112.65:416:16
1212.55:426:14
1312.55:436:12
1412.45:456:10
1512.45:466:08
1612.35:476:06
1712.35:486:04
1812.25:506:02
1912.15:516:00
2012.15:525:58
2112.05:535:56
2212.05:555:54
2311.95:565:52
2411.95:575:50
2511.85:595:48
2611.86:005:46
2711.76:015:44
2811.76:025:42
2911.66:045:40
3011.66:055:38

Solar energy in September

Daily solar energy (kWh/m²)

Average shortwave solar energy reaching the ground each day in September, about 3.9 kWh/m².

For context, solar energy here swings from a low near 1.16 kWh/m² to a high of 6.3 kWh/m² in July across the year — September's 3.9 kWh/m² falls in the middle.

024151015202530
Solar energy (kWh/m²)Level
14.7Bright
24.6Bright
34.5Bright
44.5Bright
54.4Bright
64.4Bright
74.3Bright
84.3Bright
94.2Bright
104.2Bright
114.1Bright
124.1Bright
134.0Bright
144.0Moderate
153.9Moderate
163.8Moderate
173.8Moderate
183.7Moderate
193.7Moderate
203.6Moderate
213.6Moderate
223.5Moderate
233.5Moderate
243.5Moderate
253.4Moderate
263.4Moderate
273.3Moderate
283.3Moderate
293.2Moderate
303.2Moderate
Planning a trip in September

Is September a good time to visit Rijeka?

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

6.2
Sightseeing
4th-best month of the year
3.5
Beach & pool
4th-best month of the year

September is a reasonable time to visit Rijeka for sightseeing.

What to pack for Rijeka in September

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

In September, Rijeka sees daytime highs around 20°C and nights near 14°C. Worth packing: rain gear. About 12 days see rain.

rain gear

Sea temperature near Rijeka in September

The nearest coast averages about 21°C in September — the other half of the beach question. The full-year curve and swim-comfort zones are below.

The sea offshore is warmest in August at about 23°C and coldest in February near 10°C.

It's comfortable for a long swim from Jun 10 to Sep 22 — about 3.5 months when the water holds above 20°C.

10°15°20°25°JanFebMarAprMayJunJulAugSepOctNovDecbracingcoolrefreshingwarmcomfortable to swim
Sea temperature (°C)Comfort
Jan10Bracing
Feb10Bracing
Mar10Bracing
Apr12Bracing
May17Cool
Jun21Refreshing
Jul23Refreshing
Aug23Refreshing
Sep21Refreshing
Oct18Cool
Nov15Cool
Dec12Bracing

UV index in Rijeka 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 Rijeka peaks around July 17 at about 9 (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 highModerateLowJul 17UV 9Jan 1UV 1
UV index (midday)Level
Jan1Low
Feb2Moderate
Mar5Moderate
Apr7High
May7High
Jun8Very high
Jul9Very high
Aug8Very high
Sep5High
Oct3Moderate
Nov2Low
Dec1Low
Location & terrain

Where is Rijeka?

Rijeka sits at 45.3°N, 14.4°E, 12 m above sea level, in Croatia. The nearest listed city is Cres, 41 km away.

CresPostojnaDivačaKoperTriesteRovinjPulaPiran

Topography around Rijeka

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

Within 3 km, the terrain around Rijeka has significant variations in elevation — a maximum elevation change of 379 m around an average of 77 m above sea level; within 16 km, very significant variations in elevation — a maximum elevation change of 1,375 m; within 80 km, very significant variations in elevation — a maximum elevation change of 1,767 m.

The land around Rijeka is covered by water (44%), trees (29%) and artificial surfaces (25%) within 3 km, trees (51%) and water (38%) within 16 km, and trees (62%) and water (24%) within 80 km.

3 km
379 m
16 km
1,375 m
80 km
1,767 m
treesshrubsgrasslandcroplandartificial surfaceswater
September weather nearby: Cres 41 km · Postojna 53 km · Divača 54 km · Koper 61 km · Trieste 63 km · Rovinj 69 km · Pula 69 km · Piran 72 km

Croatia travel facts

Travel advisory
Level 1
Exercise Normal Precautions
Power plugs
Type C / F
230 V · 50 Hz
Prices
≈ 53% of US
price level, 2025
GDP per capita
$27,104
2025
Happiness
6.0 / 10
World Happiness, 2025
Safe drinking water
87%
of population, 2024
Homicide rate
0.7
per 100k, 2023
Road deaths
7.9
per 100k/yr, 2019
Income group
High
World Bank
English
Very high
EF EPI 617
Religion
Roman Catholic 79%other Christian 5%none or atheist 5%Orthodox 3%

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 Rijeka (45.3267°, 14.4424°, elevation 12 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. Sea temperatures are the NOAA OISST v2.1 1991–2020 monthly climatology (public domain), sampled at the nearest ocean point. UV index is derived from CAMS (Copernicus Atmosphere Monitoring Service) clear-sky UV data — contains modified Copernicus Atmosphere Monitoring Service information. Topography is sampled from the Copernicus DEM GLO-90 elevation model (© ESA/Airbus) and ESA WorldCover 2021 land cover (CC BY 4.0).