Koper in Fall
In fall (September, October and November), Koper sees average daytime highs around 17°C and overnight lows near 12°C, with 471 mm of precipitation over about 35 wet days across the season. It is the 2nd-warmest season and the wettest season of the year.
Over the season highs ease from about 25°C in early September to 10°C by late November. The sky is clear or mostly clear about 37% of the time across fall, and the air most often feels dry.
Fall is Koper's 2nd-best season to visit on our travel score. For the whole year in context, see Koper's year-round climate.
- Avg daytime high
- 17°C
- 2nd-warmest season
- Avg overnight low
- 12°C
- Precipitation
- 471 mm
- 35 wet days
- Avg wind
- 10 km/h
- Travel score
- 5.1
- 2nd-best season
- Months
- Sep · Oct · Nov
Temperature in Koper in Fall
Over the season highs ease from about 25°C in early September to 10°C by late November.
A typical fall day in Koper reaches about 17°C and drops to 12°C overnight. The warmest of the three months is September, the coolest November.
How fall really feels in Koper
Once humidity and wind are folded in, fall brings about 0 days that feel above 32°C and 0 that feel at or below 0°C.
fall 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 the three fall months (September, October and November) compare with the rest of the year — the season's months are highlighted.
| Month | High / Low (°C) | Rainfall (mm) | Wet days | Snow days | Daylight (hours) | Travel score |
|---|---|---|---|---|---|---|
| Jan | 7° / 3° | 77 | 9.1 | 0.9 | 8.9 | 1.1 |
| Feb | 9° / 3° | 85 | 8.5 | 1.5 | 10.1 | 1.6 |
| Mar | 12° / 6° | 86 | 9.3 | 0.7 | 11.6 | 3.3 |
| Apr | 16° / 9° | 95 | 11.2 | 0.2 | 13.2 | 4.8 |
| May | 20° / 14° | 103 | 11.7 | 0 | 14.7 | 6.2 |
| Jun | 24° / 18° | 85 | 10.1 | 0 | 15.4 | 7.0 |
| Jul | 27° / 20° | 62 | 8.2 | 0 | 15.1 | 7.2 |
| Aug | 27° / 20° | 89 | 8.5 | 0 | 13.9 | 7.1 |
| Sep | 22° / 16° | 147 | 10.3 | 0 | 12.3 | 6.8 |
| Oct | 18° / 12° | 157 | 12.2 | 0 | 10.7 | 5.5 |
| Nov | 12° / 8° | 167 | 12.7 | 0.3 | 9.3 | 3.1 |
| Dec | 8° / 4° | 112 | 9.9 | 0.9 | 8.6 | 1.5 |
Cloud cover in Fall
The sky is clear or mostly clear about 37% of the time across fall.
Chance of precipitation in Fall
Koper gets around 471 mm of rain and snow over 35 wet days across fall. The line is the day-by-day chance of measurable precipitation.
Humidity in Fall
Most of fall feels dry — the stacked bands show each day's mix of comfort levels, read off the dew point.
Wind in Fall
Winds average 10 km/h across fall.
Sunrise & sunset in Fall
Daylight runs from about 13 h 06 min in early September to 8 h 48 min by late November. The lit band spans sunrise to sunset each day.
Solar energy in Fall
Average shortwave solar energy reaching the ground each day across fall, about 2.7 kWh/m².
Is fall a good time to visit Koper?
Our two travel scores rate fall for general sightseeing and for beach or pool weather — 0 (poor) to 10 (ideal), averaged across the three months.
fall is a reasonable time to visit Koper for sightseeing.
What to pack for Koper in Fall
From fall's temperature range, rain chance, sun and wind — what's worth putting in the bag.
In fall, Koper sees daytime highs around 17°C and nights near 12°C. Worth packing: light clothes, a warm layer and rain gear. About 35 days see rain.
Sea temperature near Koper in Fall
The nearest coast averages about 19°C across fall — 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.
| Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Sea temperature (°C) | 11 | 10 | 10 | 13 | 18 | 23 | 25 | 25 | 23 | 19 | 16 | 13 |
| Comfort | Bracing | Bracing | Bracing | Bracing | Cool | Refreshing | Warm | Warm | Refreshing | Cool | Cool | Bracing |
| Sea temperature (°C) | Comfort | |
|---|---|---|
| Jan | 11 | Bracing |
| Feb | 10 | Bracing |
| Mar | 10 | Bracing |
| Apr | 13 | Bracing |
| May | 18 | Cool |
| Jun | 23 | Refreshing |
| Jul | 25 | Warm |
| Aug | 25 | Warm |
| Sep | 23 | Refreshing |
| Oct | 19 | Cool |
| Nov | 16 | Cool |
| Dec | 13 | Bracing |
UV index in Koper in Fall
Clear-sky midday UV across fall averages around 3 — 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.
| Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| UV index (midday) | 1 | 2 | 4 | 7 | 7 | 8 | 8 | 7 | 5 | 3 | 2 | 1 |
| Level | Low | Moderate | Moderate | High | High | Very high | Very high | Very high | Moderate | Moderate | Low | Low |
| UV index (midday) | Level | |
|---|---|---|
| Jan | 1 | Low |
| Feb | 2 | Moderate |
| Mar | 4 | Moderate |
| Apr | 7 | High |
| May | 7 | High |
| Jun | 8 | Very high |
| Jul | 8 | Very high |
| Aug | 7 | Very high |
| Sep | 5 | Moderate |
| Oct | 3 | Moderate |
| Nov | 2 | Low |
| Dec | 1 | Low |
Air quality in Koper in Fall
Average fine-particle pollution (PM2.5) through the year — so you can see where fall 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).
| Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| PM2.5 (µg/m³) | 22 | 20 | 20 | 19 | 16 | 16 | 16 | 13 | 12 | 14 | 14 | 18 |
| Level | Moderate | Moderate | Moderate | Moderate | Moderate | Moderate | Moderate | Moderate | Moderate | Moderate | Moderate | Moderate |
| PM2.5 (µg/m³) | Level | |
|---|---|---|
| Jan | 22 | Moderate |
| Feb | 20 | Moderate |
| Mar | 20 | Moderate |
| Apr | 19 | Moderate |
| May | 16 | Moderate |
| Jun | 16 | Moderate |
| Jul | 16 | Moderate |
| Aug | 13 | Moderate |
| Sep | 12 | Moderate |
| Oct | 14 | Moderate |
| Nov | 14 | Moderate |
| Dec | 18 | Moderate |
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.
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.
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
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.