Koper in Spring
In spring (March, April and May), Koper sees average daytime highs around 16°C and overnight lows near 10°C, with 284 mm of precipitation over about 32 wet days across the season. It is the 3rd-warmest season and the 2nd-wettest season.
Over the season highs climb from about 10°C in early March to 22°C by late May. The sky is clear or mostly clear about 38% of the time across spring, and the air most often feels dry.
Spring is Koper's 3rd-best season to visit on our travel score. For the whole year in context, see Koper's year-round climate.
- Avg daytime high
- 16°C
- 3rd-warmest season
- Avg overnight low
- 10°C
- Precipitation
- 284 mm
- 32 wet days
- Avg wind
- 10 km/h
- Travel score
- 4.8
- 3rd-best season
- Months
- Mar · Apr · May
Temperature in Koper in Spring
Over the season highs climb from about 10°C in early March to 22°C by late May.
A typical spring day in Koper reaches about 16°C and drops to 10°C overnight. The warmest of the three months is May, the coolest March.
How spring really feels in Koper
Once humidity and wind are folded in, spring brings about 0 days that feel above 32°C and 0 that feel at or below 0°C.
spring 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 spring months (March, April and May) 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 Spring
The sky is clear or mostly clear about 38% of the time across spring.
Chance of precipitation in Spring
Koper gets around 284 mm of rain and snow over 32 wet days across spring. The line is the day-by-day chance of measurable precipitation.
Humidity in Spring
Most of spring feels dry — the stacked bands show each day's mix of comfort levels, read off the dew point.
Wind in Spring
Winds average 10 km/h across spring.
Sunrise & sunset in Spring
Daylight runs from about 10 h 48 min in early March to 15 h 12 min by late May. The lit band spans sunrise to sunset each day.
Solar energy in Spring
Average shortwave solar energy reaching the ground each day across spring, about 4.8 kWh/m².
Is spring a good time to visit Koper?
Our two travel scores rate spring for general sightseeing and for beach or pool weather — 0 (poor) to 10 (ideal), averaged across the three months.
spring is a reasonable time to visit Koper for sightseeing.
What to pack for Koper in Spring
From spring's temperature range, rain chance, sun and wind — what's worth putting in the bag.
In spring, Koper sees daytime highs around 16°C and nights near 10°C. Pack a warm layer. Worth having: rain gear and sun protection. About 32 days see rain.
Sea temperature near Koper in Spring
The nearest coast averages about 14°C across spring — 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 Spring
Clear-sky midday UV across spring averages around 6 — 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 Spring
Average fine-particle pollution (PM2.5) through the year — so you can see where spring 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.