Piran weather in May

In May, Piran sees average daytime highs of 19°C and overnight lows near 16°C, with 82 mm of rain across 9.3 wet days and about 14.7 hours of daylight. It is the 5th-warmest and 7th-wettest month of the year here.

Highs climb over the month, from about 17°C in the first days to 21°C by the end. The sky is clear or mostly clear about 43% of the time in May, and the air most often feels dry.

Daylight stretches from about 14 hours at the start of May to 15 h 12 min by month's end. Set against the rest of the year, May is Piran's 5th-clearest and 9th-windiest month. For the whole year in context, see Piran's year-round climate.

Daytime high
19°
5th warmest
Overnight low
16°
8th coldest
Rainfall
82 mm
9.3 wet days
Daylight
14 h 42 min
4:41 AM – 7:23 PM
Cloud cover
49%
5th clearest
Wind
13 km/h
9th windiest
Solar energy
5.94 kWh/m²
Travel score
6.3
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 May

Average highAverage lowShaded bands: 10–90% of days

Highs climb over the month, from about 17°C in the first days to 21°C by the end.

A typical May day in Piran reaches about 19°C in the afternoon and slips back to 16°C overnight — a 3°C spread between the day's warmth and the night's chill. On most days the high lands between 16°C and 21°C. Set against its neighbours, May runs about 5°C warmer than April and about 4°C cooler than June.

10°15°20°25°151015202531
Avg high (°C)Avg low (°C)
11714
21714
31715
41715
51715
61715
71815
81815
91815
101816
111816
121816
131816
141916
151916
161916
171916
181917
191917
201917
212017
222017
232017
242017
252018
262018
272018
282118
292118
302118
312118

Piran weather by month

How May compares with the rest of the year at a glance. May is the 5th-warmest and 7th-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 May

ClearMostly clearPartly cloudyMostly cloudyOvercast

The sky is clear or mostly clear about 43% of the time in May.

Beyond those clear spells, partly cloudy skies cover about 18% of May, with mostly cloudy or overcast conditions the remaining 40%. Skies tend to open up as the month goes on.

0%25%50%75%100%151015202531
Clearer (%)Cloudier (%)
15743
25743
35842
45743
55842
65842
75842
85842
95842
105842
115941
125941
135941
145941
155941
165941
175941
186040
196040
206139
216238
226337
236337
246337
256337
266436
276436
286535
296535
306535
316535

Chance of precipitation in May

Any precipitation

Piran gets around 82 mm of rain over 9.3 wet days in May. The line is the day-by-day chance of measurable precipitation.

Day to day, the chance of measurable rain averages around 30% and peaks near 33% on the wettest days.

0%10%20%30%40%151015202531
Rain chance (%)
132
232
333
433
533
633
733
833
933
1033
1132
1232
1332
1432
1531
1631
1731
1830
1930
2029
2129
2228
2328
2428
2527
2627
2727
2827
2927
3027
3127

Humidity in May

DryComfortableHumidMuggyOppressiveMiserable

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

By dew point, May lands in the dry band about 41% of days. It rarely turns muggy — the humid and sticky bands barely register.

0%25%50%75%100%151015202531
Dry (%)Comfortable (%)Humid (%)Muggy (%)Oppressive (%)
16532300
26333400
36035500
45836600
55637700
65438800
75239900
850401000
948401100
1047401300
1146411400
1244411500
1343411610
1442411710
1540411810
1639401920
1738402020
1837392130
1936382230
2036372340
2135362450
2234352560
2333342670
2432332780
2531322890
26303129100
27293030120
28282931130
29262832140
30252733151
31242633171

Wind in May

Winds average 13 km/h in May.

Across May, daily wind ranges from about 12 km/h on the calmest days to 13 km/h at its breeziest. It stays fairly steady from day to day.

051015151015202531
Wind speed (km/h)Feels
113light breeze
213light breeze
313light breeze
413light breeze
513light breeze
613light breeze
713light breeze
813light breeze
913light breeze
1013light breeze
1113light breeze
1213light breeze
1313light breeze
1413light breeze
1513light breeze
1613light breeze
1713light breeze
1813light breeze
1913light breeze
2013light breeze
2113light breeze
2213light breeze
2313light breeze
2412light breeze
2512light breeze
2612light breeze
2712light breeze
2812light breeze
2912light breeze
3012light breeze
3112light breeze

Sunrise & sunset in May

DaylightNight

Daylight runs from about 14 hours at the start of May to 15 h 12 min by month's end. The lit band spans sunrise to sunset each day.

Days grow by about 72 minutes over May. Sunrise moves from 5:02 AM to 4:27 AM, and sunset from 7:04 PM to 7:39 PM.

12 AM4 AM8 AM12 PM4 PM8 PM12 AM151015202531
Daylight (h)Sunrise (AM)Sunset (PM)
114.05:027:04
214.15:007:05
314.14:597:07
414.24:577:08
514.24:567:09
614.34:547:10
714.34:537:12
814.44:517:13
914.44:507:14
1014.44:497:15
1114.54:477:17
1214.54:467:18
1314.64:457:19
1414.64:447:20
1514.74:427:22
1614.74:417:23
1714.74:407:24
1814.84:397:25
1914.84:387:26
2014.84:377:27
2114.94:367:29
2214.94:357:30
2314.94:347:31
2415.04:337:32
2515.04:327:33
2615.04:317:34
2715.14:307:35
2815.14:307:36
2915.14:297:37
3015.24:287:38
3115.24:277:39

Solar energy in May

Daily solar energy (kWh/m²)

Average shortwave solar energy reaching the ground each day in May, about 5.94 kWh/m².

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 — May's 5.94 kWh/m² sits near the top of that range.

0246151015202531
Solar energy (kWh/m²)Level
15.5Bright
25.5Bright
35.5Bright
45.6Bright
55.6Bright
65.6Bright
75.7Bright
85.7Bright
95.7Bright
105.7Bright
115.8Bright
125.8Bright
135.8Bright
145.8Bright
155.9Bright
165.9Bright
175.9Bright
185.9Bright
196.0Bright
206.0Intense
216.0Intense
226.1Intense
236.1Intense
246.1Intense
256.2Intense
266.2Intense
276.2Intense
286.2Intense
296.3Intense
306.3Intense
316.3Intense
Planning a trip in May

Is May a good time to visit Piran?

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

6.3
Sightseeing
5th-best month of the year
2.7
Beach & pool
5th-best month of the year

May is a reasonable time to visit Piran for sightseeing.

What to pack for Piran in May

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

In May, Piran sees daytime highs around 19°C and nights near 16°C. Worth packing: rain gear and sun protection. About 9 days see rain.

rain gearsun protection

Sea temperature near Piran in May

The nearest coast averages about 18°C in May — 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 May

LowModerateHighVery highExtreme

Clear-sky midday UV in May 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 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 May

GoodModeratePoorUnhealthyVery unhealthy

Average fine-particle pollution (PM2.5) through the year — so you can see where May 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
May 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).