Koper weather in August

In August, Koper sees average daytime highs of 27°C and overnight lows near 20°C, with 89 mm of rain across 8.5 wet days and about 13.9 hours of daylight. It is the 1st-warmest and 7th-wettest month of the year here.

Highs ease over the month, from about 28°C in the first days to 25°C by the end. The sky is clear or mostly clear about 58% of the time in August, and the air most often feels humid.

Daylight stretches from about 14 h 36 min at the start of August to 13 h 12 min by month's end. Set against the rest of the year, August is Koper's 1st-clearest and 11th-windiest month. For the whole year in context, see Koper's year-round climate.

Daytime high
27°
1st warmest
Overnight low
20°
11th coldest
Rainfall
89 mm
8.5 wet days
Daylight
13 h 54 min
5:11 AM – 7:07 PM
Cloud cover
38%
1st clearest
Wind
8 km/h
11th windiest
Solar energy
5.62 kWh/m²
Travel score
7.1
out of 10

Koper is city in southwest Slovenia.

Air quality
Good
PM10 16.8 µg/m³ · 2019
Density
1,981/km²
people per km²

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

Temperature in August

Average highAverage lowShaded bands: 10–90% of days

Highs ease over the month, from about 28°C in the first days to 25°C by the end.

A typical August day in Koper reaches about 27°C in the afternoon and slips back to 20°C overnight — a 7°C spread between the day's warmth and the night's chill. On most days the high lands between 23°C and 31°C. Set against its neighbours, August runs on par with July and about 5°C warmer than September.

10°15°20°25°30°35°151015202531
Avg high (°C)Avg low (°C)
12821
22821
32821
42821
52821
62821
72821
82821
92821
102821
112820
122820
132820
142720
152720
162720
172720
182720
192720
202720
212720
222720
232719
242619
252619
262619
272619
282619
292519
302518
312518

How August really feels in Koper

Once humidity and wind are folded in, August 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

August sits comfortably in between — no days that feel dangerously hot or drop to a hard freeze once humidity and wind are folded in.

Koper weather by month

How August compares with the rest of the year at a glance. August is the 1st-warmest and 7th-wettest month here — the current month is highlighted below.

MonthHigh / Low (°C)Rainfall (mm)Wet daysSnow daysDaylight (hours)Travel score
Jan / 779.10.98.91.1
Feb / 858.51.510.11.6
Mar12° / 869.30.711.63.3
Apr16° / 9511.20.213.24.8
May20° / 14°10311.7014.76.2
Jun24° / 18°8510.1015.47.0
Jul27° / 20°628.2015.17.2
Aug27° / 20°898.5013.97.1
Sep22° / 16°14710.3012.36.8
Oct18° / 12°15712.2010.75.5
Nov12° / 16712.70.39.33.1
Dec / 1129.90.98.61.5

Cloud cover in August

ClearMostly clearPartly cloudyMostly cloudyOvercast

The sky is clear or mostly clear about 58% of the time in August, the clearest month of the year.

Beyond those clear spells, partly cloudy skies cover about 18% of August, with mostly cloudy or overcast conditions the remaining 25%. Skies tend to cloud over as the month goes on.

0%25%50%75%100%151015202531
Clearer (%)Cloudier (%)
17525
27525
37525
47525
57723
67723
77723
87723
97723
107723
117723
127723
137723
147822
157822
167822
177723
187723
197723
207624
217624
227426
237426
247327
257327
267228
277129
287030
297030
306931
316931

Chance of precipitation in August

Any precipitation

Koper gets around 89 mm of rain over 8.5 wet days in August. 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 30% on the wettest days.

0%10%20%30%40%151015202531
Rain chance (%)
125
225
326
426
526
626
726
827
927
1027
1127
1227
1327
1427
1527
1627
1727
1827
1927
2028
2128
2228
2328
2428
2529
2629
2729
2830
2930
3030
3130

Humidity in August

DryComfortableHumidMuggyOppressiveMiserable

Most of August feels humid — the stacked bands show each day's mix of comfort levels, read off the dew point.

By dew point, August lands in the humid band about 42% of days. Sticky, muggy-or-worse air turns up on roughly 29% of them.

0%25%50%75%100%151015202531
Dry (%)Comfortable (%)Humid (%)Muggy (%)Oppressive (%)
161638392
261637392
351737392
451737382
551738382
661838372
761838362
861839352
961940342
1061941331
1161941321
1261943311
1361944301
1461945291
1561946281
1671946271
1771947261
1871948251
1971948251
2081948241
2181948241
2291947231
23101947231
24122046221
25132045211
26152144201
27162142191
28182241181
29202340171
30212438160
31232537150

Wind in August

Winds average 8 km/h in August.

Across August, daily wind ranges from about 8 km/h on the calmest days to 9 km/h at its breeziest. It stays fairly steady from day to day.

051015151015202531
Wind speed (km/h)Feels
18calm
28calm
38calm
48calm
58calm
68calm
78calm
88calm
98calm
108calm
118calm
128calm
138calm
148calm
158calm
168calm
178calm
188calm
198calm
208calm
219calm
229calm
239calm
249calm
259calm
269calm
279calm
289calm
299calm
309calm
319calm

Sunrise & sunset in August

DaylightNight

Daylight runs from about 14 h 36 min at the start of August to 13 h 12 min by month's end. The lit band spans sunrise to sunset each day.

Days shrink by about 84 minutes over August. Sunrise moves from 4:53 AM to 5:30 AM, and sunset from 7:30 PM to 6:40 PM.

12 AM4 AM8 AM12 PM4 PM8 PM12 AM151015202531
Daylight (h)Sunrise (AM)Sunset (PM)
114.64:537:30
214.64:547:28
314.54:557:27
414.54:567:26
514.44:577:24
614.44:597:23
714.45:007:21
814.35:017:20
914.35:027:19
1014.25:037:17
1114.25:057:15
1214.15:067:14
1314.15:077:12
1414.05:087:11
1514.05:107:09
1613.95:117:07
1713.95:127:06
1813.85:137:04
1913.85:157:02
2013.75:167:01
2113.75:176:59
2213.65:186:57
2313.65:206:55
2413.55:216:54
2513.55:226:52
2613.45:236:50
2713.45:256:48
2813.35:266:46
2913.35:276:44
3013.25:296:42
3113.25:306:40

Solar energy in August

Daily solar energy (kWh/m²)

Average shortwave solar energy reaching the ground each day in August, about 5.62 kWh/m².

For context, solar energy here swings from a low near 1.2 kWh/m² to a high of 6.47 kWh/m² in July across the year — August's 5.62 kWh/m² falls in the middle.

0246151015202531
Solar energy (kWh/m²)Level
16.2Intense
26.1Intense
36.1Intense
46.1Intense
56.0Intense
66.0Intense
76.0Bright
86.0Bright
95.9Bright
105.9Bright
115.8Bright
125.8Bright
135.8Bright
145.7Bright
155.7Bright
165.7Bright
175.6Bright
185.6Bright
195.5Bright
205.5Bright
215.4Bright
225.4Bright
235.3Bright
245.3Bright
255.2Bright
265.2Bright
275.1Bright
285.0Bright
295.0Bright
304.9Bright
314.9Bright
Planning a trip in August

Is August a good time to visit Koper?

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

7.1
Sightseeing
2nd-best month of the year
7.2
Beach & pool
2nd-best month of the year

August is one of the better times to visit Koper for general sightseeing. The water and warmth also suit a beach or pool day.

What to pack for Koper in August

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

In August, Koper sees daytime highs around 27°C and nights near 20°C. Pack light clothes. Worth having: rain gear and sun protection. About 9 days see rain.

light clothesrain gearsun protection

Sea temperature near Koper in August

The nearest coast averages about 25°C in August — 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 25°C and coldest in February near 10°C.

It's comfortable for a long swim from May 31 to Oct 9 — about 4.3 months when the water holds above 20°C.

10°20°30°JanFebMarAprMayJunJulAugSepOctNovDecbracingcoolrefreshingwarmtropicalcomfortable to swim
Sea temperature (°C)Comfort
Jan11Bracing
Feb10Bracing
Mar10Bracing
Apr13Bracing
May18Cool
Jun23Refreshing
Jul25Warm
Aug25Warm
Sep23Refreshing
Oct19Cool
Nov16Cool
Dec13Bracing

UV index in Koper in August

LowModerateHighVery highExtreme

Clear-sky midday UV in August peaks around 7 — enough to warrant sun protection. The full-year curve, shaded by WHO exposure level, is below.

Under clear skies, the midday UV index in Koper 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 7 months of the year.

025710JanFebMarAprMayJunJulAugSepOctNovDecLowModerateHighVery highHighModerateLowJul 15UV 8Jan 1UV 1
UV index (midday)Level
Jan1Low
Feb2Moderate
Mar4Moderate
Apr7High
May7High
Jun8Very high
Jul8Very high
Aug7Very high
Sep5Moderate
Oct3Moderate
Nov2Low
Dec1Low

Air quality in Koper in August

GoodModeratePoorUnhealthyVery unhealthy

Average fine-particle pollution (PM2.5) through the year — so you can see where August falls, not just the annual average.

Air quality in Koper is worst in January — around 22 µg/m³ PM2.5 (moderate), about 1.8× the cleanest month (September, 12 µg/m³).

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

0102030JanFebMarAprMayJunJulAugSepOctNovDecModerateJan 1822 µg/m³Sep 1412 µg/m³
PM2.5 (µg/m³)Level
Jan22Moderate
Feb20Moderate
Mar20Moderate
Apr19Moderate
May16Moderate
Jun16Moderate
Jul16Moderate
Aug13Moderate
Sep12Moderate
Oct14Moderate
Nov14Moderate
Dec18Moderate
Location & terrain

Where is Koper?

Koper sits at 45.5°N, 13.7°E, 12 m above sea level, in Slovenia. The nearest listed city is Trieste, 12 km away.

DivačaMonfalconeGoriziaPostojnaNova Gorica

Topography around Koper

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

Within 3 km, the terrain around Koper has only modest variations in elevation — a maximum elevation change of 238 m around an average of 24 m above sea level; within 16 km, significant variations in elevation — a maximum elevation change of 575 m; within 80 km, very significant variations in elevation — a maximum elevation change of 2,150 m.

The land around Koper is covered by water (34%) and artificial surfaces (23%) within 3 km, trees (46%) and water (34%) within 16 km, and trees (48%) and water (29%) within 80 km.

3 km
238 m
16 km
575 m
80 km
2,150 m
treesshrubsgrasslandcroplandartificial surfaceswaterwetland
August weather nearby: Trieste 12 km · Piran 13 km · Divača 24 km · Monfalcone 32 km · Gorizia 44 km · Postojna 45 km · Nova Gorica 46 km · Rovinj 52 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 Koper (45.5482°, 13.7296°, 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. 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).