Piran weather in December

In December, Piran sees average daytime highs of 10°C and overnight lows near 8°C, with 116 mm of precipitation across 11.3 wet days and about 8.6 hours of daylight. It is the 10th-warmest and 4th-wettest month of the year here.

Highs ease over the month, from about 11°C in the first days to 9°C by the end. The sky is clear or mostly clear about 31% of the time in December, and the air most often feels dry.

Daylight stretches from about 8 h 48 min at the start of December to 8 h 36 min by month's end. Set against the rest of the year, December is Piran's 11th-clearest and 2nd-windiest month. For the whole year in context, see Piran's year-round climate.

Daytime high
10°
10th warmest
Overnight low
3rd coldest
Precipitation
116 mm
11.3 wet days
Daylight
8 h 30 min
7:46 AM – 4:18 PM
Cloud cover
60%
11th clearest
Wind
15 km/h
2nd windiest
Solar energy
1.2 kWh/m²
Travel score
2.3
out of 10

Piran is coastal town of Slovenia.

Density
94/km²
people per km²

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

Temperature in December

Average highAverage lowShaded bands: 10–90% of days

Highs ease over the month, from about 11°C in the first days to 9°C by the end.

A typical December day in Piran reaches about 10°C in the afternoon and slips back to 8°C overnight — a 2°C spread between the day's warmth and the night's chill. On most days the high lands between 7°C and 13°C. Set against its neighbours, December runs about 4°C cooler than November and about 1°C warmer than January.

10°15°151015202531
Avg high (°C)Avg low (°C)
1129
2119
3119
4119
5119
6119
7119
8119
9119
10118
11108
12108
13108
14108
15108
16108
17108
18108
19108
20108
21108
22107
23107
2497
2597
2697
2797
2897
2997
3097
3197

Piran weather by month

How December compares with the rest of the year at a glance. December is the 10th-warmest and 4th-wettest month here — the current month is highlighted below.

MonthHigh / Low (°C)Rainfall (mm)Wet daysSnow daysDaylight (hours)Travel score
Jan / 839.90.18.91.7
Feb / 858.90.610.11.7
Mar11° / 758.40.311.62.8
Apr14° / 12°759.3013.24.3
May19° / 16°829.3014.76.3
Jun23° / 21°647.3015.47.6
Jul26° / 23°475.6015.17.9
Aug26° / 23°787013.97.7
Sep22° / 19°1429.6012.36.9
Oct18° / 16°14112.3010.75.7
Nov14° / 12°17013.90.19.33.6
Dec10° / 11611.30.48.62.3

Cloud cover in December

ClearMostly clearPartly cloudyMostly cloudyOvercast

The sky is clear or mostly clear about 31% of the time in December.

Beyond those clear spells, partly cloudy skies cover about 12% of December, with mostly cloudy or overcast conditions the remaining 57%.

0%25%50%75%100%151015202531
Clearer (%)Cloudier (%)
14159
24159
34258
44258
54258
64258
74357
84357
94456
104456
114357
124456
134456
144456
154456
164456
174456
184258
194258
204258
214258
224258
234357
244357
254357
264357
274456
284456
294555
304456
314456

Chance of precipitation in December

Any precipitationSnow

Piran gets around 116 mm of rain and snow over 11.3 wet days in December. The line is the day-by-day chance of measurable precipitation.

Day to day, the chance of measurable precipitation averages around 37% and peaks near 40% on the wettest days, and about 0 day brings snow.

0%10%20%30%40%50%151015202531
Rain chance (%)Snow chance (%)
1400
2390
3390
4380
5380
6381
7371
8371
9371
10371
11371
12371
13362
14362
15372
16372
17372
18372
19372
20372
21372
22372
23372
24372
25372
26372
27372
28361
29361
30361
31361

Humidity in December

DryComfortableHumidMuggyOppressiveMiserable

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

By dew point, December lands in the dry band about 100% of days. It rarely turns muggy — the humid and sticky bands barely register.

0%25%50%75%100%151015202531
Dry (%)Comfortable (%)
1982
2982
3982
4991
5991
6991
7991
8991
91000
101000
111000
121000
131000
141000
151000
161000
171000
181000
191000
201000
211000
221000
231000
241000
251000
261000
271000
281000
291000
301000
311000

Wind in December

Winds average 15 km/h in December.

Across December, daily wind ranges from about 14 km/h on the calmest days to 16 km/h at its breeziest. It stays fairly steady from day to day.

05101520151015202531
Wind speed (km/h)Feels
116light breeze
216light breeze
316light breeze
416light breeze
516light breeze
616light breeze
716light breeze
816light breeze
915light breeze
1015light breeze
1115light breeze
1215light breeze
1315light breeze
1415light breeze
1515light breeze
1615light breeze
1715light breeze
1815light breeze
1915light breeze
2015light breeze
2115light breeze
2215light breeze
2315light breeze
2415light breeze
2515light breeze
2615light breeze
2715light breeze
2815light breeze
2915light breeze
3014light breeze
3114light breeze

Sunrise & sunset in December

DaylightNight

Daylight runs from about 8 h 48 min at the start of December to 8 h 36 min by month's end. The lit band spans sunrise to sunset each day.

Days shrink by about 12 minutes over December. Sunrise moves from 7:32 AM to 7:52 AM, and sunset from 4:19 PM to 4:26 PM.

12 AM4 AM8 AM12 PM4 PM8 PM12 AM151015202531
Daylight (h)Sunrise (AM)Sunset (PM)
18.87:324:19
28.77:334:18
38.77:344:18
48.77:364:18
58.77:374:18
68.77:384:17
78.67:394:17
88.67:404:17
98.67:404:17
108.67:414:17
118.67:424:17
128.67:434:17
138.67:444:17
148.57:454:17
158.57:454:18
168.57:464:18
178.57:474:18
188.57:474:18
198.57:484:19
208.57:494:19
218.57:494:19
228.57:504:20
238.57:504:20
248.57:504:21
258.57:514:21
268.57:514:22
278.57:514:23
288.57:524:23
298.57:524:24
308.57:524:25
318.67:524:26

Solar energy in December

Daily solar energy (kWh/m²)

Average shortwave solar energy reaching the ground each day in December, about 1.2 kWh/m² — the year's lowest.

For context, solar energy here swings from a low near 1.2 kWh/m² to a high of 6.52 kWh/m² in July across the year — December's 1.2 kWh/m² sits near the bottom.

00.511.52151015202531
Solar energy (kWh/m²)Level
11.3Dim
21.3Dim
31.3Dim
41.3Dim
51.3Dim
61.3Dim
71.3Dim
81.2Dim
91.2Dim
101.2Dim
111.2Dim
121.2Dim
131.2Dim
141.2Dim
151.2Dim
161.2Dim
171.2Dim
181.2Dim
191.2Dim
201.2Dim
211.2Dim
221.2Dim
231.2Dim
241.2Dim
251.2Dim
261.2Dim
271.2Dim
281.2Dim
291.2Dim
301.2Dim
311.2Dim
Planning a trip in December

Is December a good time to visit Piran?

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

2.3
Sightseeing
10th-best month of the year
0.0
Beach & pool
9th-best month of the year

December is a weaker month for outdoor sightseeing in Piran.

What to pack for Piran in December

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

In December, Piran sees daytime highs around 10°C and nights near 8°C. Pack a warm layer. Worth having: rain gear. About 11 days see rain.

a warm layerrain gear

Sea temperature near Piran in December

The nearest coast averages about 13°C in December — 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 Piran in December

LowModerateHighVery highExtreme

Clear-sky midday UV in December peaks around 1. The full-year curve, shaded by WHO exposure level, is below.

Under clear skies, the midday UV index in Piran 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 Piran in December

GoodModeratePoorUnhealthyVery unhealthy

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

Air quality in Piran 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 Piran?

Piran sits at 45.5°N, 13.6°E, 0 m above sea level, in Slovenia. The nearest listed city is Koper, 13 km away.

TriesteMonfalconeDivačaGoriziaNova GoricaPostojna

Topography around Piran

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

Within 3 km, the terrain around Piran has only modest variations in elevation — a maximum elevation change of 172 m around an average of 10 m above sea level; within 16 km, significant variations in elevation — a maximum elevation change of 412 m; within 80 km, very significant variations in elevation — a maximum elevation change of 1,859 m.

The land around Piran is covered by water (82%) within 3 km, water (65%) and trees (20%) within 16 km, and trees (43%) and water (31%) within 80 km.

3 km
172 m
16 km
412 m
80 km
1,859 m
treesshrubsgrasslandcroplandartificial surfaceswater
December weather nearby: Koper 13 km · Trieste 21 km · Monfalcone 31 km · Divača 36 km · Gorizia 46 km · Nova Gorica 48 km · Rovinj 50 km · Postojna 57 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 Piran (45.5278°, 13.5706°, 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. 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).