Postojna in Summer
In summer (June, July and August), Postojna sees average daytime highs around 24°C and overnight lows near 14°C, with 403 mm of rain over about 40 wet days across the season. It is the warmest season of the year and the 2nd-wettest season.
Across summer, daytime highs hold fairly steady around 24°C. The sky is clear or mostly clear about 42% of the time across summer, and the air most often feels comfortable.
Summer is Postojna's best season of the year to visit on our travel score. For the whole year in context, see Postojna's year-round climate.
- Avg daytime high
- 24°C
- warmest season of the year
- Avg overnight low
- 14°C
- Rainfall
- 403 mm
- 40 wet days
- Avg wind
- 7 km/h
- Travel score
- 6.5
- best season of the year
- Months
- Jun · Jul · Aug
Temperature in Postojna in Summer
Across summer, daytime highs hold fairly steady around 24°C.
A typical summer day in Postojna reaches about 24°C and drops to 14°C overnight. The warmest of the three months is July, the coolest June.
How summer really feels in Postojna
Once humidity and wind are folded in, summer brings about 0 days that feel above 32°C and 0 that feel at or below 0°C.
summer sits comfortably in between — no days that feel dangerously hot or drop to a hard freeze once humidity and wind are folded in.
Postojna weather by month
How the three summer months (June, July and August) 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 | 3° / -3° | 90 | 9.9 | 5.3 | 8.9 | 0.0 |
| Feb | 5° / -2° | 106 | 10 | 5.3 | 10.1 | 0.2 |
| Mar | 9° / 1° | 106 | 11.1 | 3.7 | 11.6 | 2.0 |
| Apr | 14° / 5° | 122 | 13.7 | 1.2 | 13.3 | 3.7 |
| May | 18° / 10° | 142 | 14.8 | 0 | 14.7 | 5.3 |
| Jun | 22° / 13° | 137 | 14.4 | 0 | 15.5 | 6.1 |
| Jul | 25° / 15° | 122 | 12.7 | 0 | 15.2 | 6.8 |
| Aug | 24° / 15° | 145 | 12.4 | 0 | 13.9 | 6.7 |
| Sep | 19° / 11° | 176 | 12.1 | 0 | 12.3 | 5.8 |
| Oct | 14° / 7° | 148 | 12.1 | 0.4 | 10.7 | 4.0 |
| Nov | 9° / 3° | 172 | 12.6 | 2.3 | 9.3 | 1.5 |
| Dec | 4° / -2° | 122 | 10.3 | 4.4 | 8.5 | 0.0 |
Cloud cover in Summer
The sky is clear or mostly clear about 42% of the time across summer.
Chance of precipitation in Summer
Postojna gets around 403 mm of rain over 40 wet days across summer. The line is the day-by-day chance of measurable precipitation.
Humidity in Summer
Most of summer feels comfortable — the stacked bands show each day's mix of comfort levels, read off the dew point.
Wind in Summer
Winds average 7 km/h across summer.
Sunrise & sunset in Summer
Daylight runs from about 15 h 12 min in early June to 13 h 12 min by late August. The lit band spans sunrise to sunset each day.
Solar energy in Summer
Average shortwave solar energy reaching the ground each day across summer, about 5.8 kWh/m².
Is summer a good time to visit Postojna?
Our two travel scores rate summer for general sightseeing and for beach or pool weather — 0 (poor) to 10 (ideal), averaged across the three months.
summer is a reasonable time to visit Postojna for sightseeing.
What to pack for Postojna in Summer
From summer's temperature range, rain chance, sun and wind — what's worth putting in the bag.
In summer, Postojna sees daytime highs around 24°C and nights near 14°C. Pack rain gear and sun protection. Worth having: light clothes. About 40 days see rain.
Sea temperature near Postojna in Summer
The nearest coast averages about 23°C across summer — the other half of the beach question. The full-year curve and swim-comfort zones are below.
The sea at the nearest coast (about 46 km away) 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.
| Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Sea temperature (°C) | 10 | 10 | 10 | 12 | 17 | 21 | 23 | 23 | 21 | 18 | 15 | 12 |
| Comfort | Bracing | Bracing | Bracing | Bracing | Cool | Refreshing | Refreshing | Refreshing | Refreshing | Cool | Cool | Bracing |
| Sea temperature (°C) | Comfort | |
|---|---|---|
| Jan | 10 | Bracing |
| Feb | 10 | Bracing |
| Mar | 10 | Bracing |
| Apr | 12 | Bracing |
| May | 17 | Cool |
| Jun | 21 | Refreshing |
| Jul | 23 | Refreshing |
| Aug | 23 | Refreshing |
| Sep | 21 | Refreshing |
| Oct | 18 | Cool |
| Nov | 15 | Cool |
| Dec | 12 | Bracing |
UV index in Postojna in Summer
Clear-sky midday UV across summer averages around 8 (very high — sun protection essential). The full-year curve, shaded by WHO exposure level, is below.
Under clear skies, the midday UV index in Postojna peaks around July 16 at about 9 (very high) — sunscreen, a hat and midday shade are essential. It bottoms out near January 10 at about 1 (low).
The index reaches 3 or more — the level where the WHO recommends sun protection — in 8 months of the year.
| Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| UV index (midday) | 1 | 2 | 5 | 7 | 7 | 8 | 9 | 8 | 5 | 3 | 2 | 1 |
| Level | Low | Moderate | Moderate | Very high | High | Very high | Very high | Very high | High | Moderate | Low | Low |
| UV index (midday) | Level | |
|---|---|---|
| Jan | 1 | Low |
| Feb | 2 | Moderate |
| Mar | 5 | Moderate |
| Apr | 7 | Very high |
| May | 7 | High |
| Jun | 8 | Very high |
| Jul | 9 | Very high |
| Aug | 8 | Very high |
| Sep | 5 | High |
| Oct | 3 | Moderate |
| Nov | 2 | Low |
| Dec | 1 | Low |
Air quality in Postojna in Summer
Average fine-particle pollution (PM2.5) through the year — so you can see where summer falls, not just the annual average.
Air quality in Postojna is worst in January — around 19 µg/m³ PM2.5 (moderate), and holds fairly steady the rest of the year.
Modeled monthly averages (CAMS reanalysis, 2015–2024).
| Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| PM2.5 (µg/m³) | 19 | 17 | 18 | 18 | 15 | 16 | 14 | 13 | 12 | 13 | 13 | 15 |
| Level | Moderate | Moderate | Moderate | Moderate | Moderate | Moderate | Moderate | Moderate | Good | Moderate | Moderate | Moderate |
| PM2.5 (µg/m³) | Level | |
|---|---|---|
| Jan | 19 | Moderate |
| Feb | 17 | Moderate |
| Mar | 18 | Moderate |
| Apr | 18 | Moderate |
| May | 15 | Moderate |
| Jun | 16 | Moderate |
| Jul | 14 | Moderate |
| Aug | 13 | Moderate |
| Sep | 12 | Good |
| Oct | 13 | Moderate |
| Nov | 13 | Moderate |
| Dec | 15 | Moderate |
Where is Postojna?
Postojna sits at 45.8°N, 14.2°E, 0 m above sea level, in Slovenia. The nearest listed city is Divača, 21 km away.
Topography around Postojna
How much the land rises and falls, and what covers it, within 3, 16 and 80 km of Postojna.
Within 3 km, the terrain around Postojna has significant variations in elevation — a maximum elevation change of 409 m around an average of 606 m above sea level; within 16 km, large variations in elevation — a maximum elevation change of 1,054 m; within 80 km, extreme variations in elevation — a maximum elevation change of 2,695 m.
The land around Postojna is covered by trees (69%) and grassland (20%) within 3 km, trees (77%) within 16 km, and trees (70%) 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 Postojna (45.7743°, 14.2153°, elevation 0 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.