Siena weather in May

In May, Siena sees average daytime highs of 22°C and overnight lows near 11°C, with 71 mm of rain across 10.1 wet days and about 14.5 hours of daylight. It is the 5th-warmest and 6th-wettest month of the year here.

Highs climb over the month, from about 20°C in the first days to 23°C by the end. The sky is clear or mostly clear about 37% of the time in May, and the air most often feels dry.

Daylight stretches from about 13 h 54 min at the start of May to 14 h 54 min by month's end. Set against the rest of the year, May is Siena's 5th-clearest and 8th-windiest month. For the whole year in context, see Siena's year-round climate.

Daytime high
22°
5th warmest
Overnight low
11°
8th coldest
Rainfall
71 mm
10.1 wet days
Daylight
14 h 30 min
4:56 AM – 7:25 PM
Cloud cover
52%
5th clearest
Wind
8 km/h
8th windiest
Solar energy
6.1 kWh/m²
Travel score
6.7
out of 10
Air quality
Good
PM10 18.4 µg/m³ · 2019

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 20°C in the first days to 23°C by the end.

A typical May day in Siena reaches about 22°C in the afternoon and slips back to 11°C overnight — a 10°C spread between the day's warmth and the night's chill. On most days the high lands between 17°C and 25°C. Set against its neighbours, May runs about 4°C warmer than April and about 4°C cooler than June.

10°15°20°25°30°151015202531
Avg high (°C)Avg low (°C)
11910
22010
32010
42010
52010
62010
72010
82010
92110
102111
112111
122111
132111
142111
152111
162111
172211
182211
192211
202212
212212
222212
232312
242312
252312
262312
272312
282313
292313
302413
312413

How May really feels in Siena

Once humidity and wind are folded in, May averages 0 days that feel above 32°C and 0 that feel at or below 0°C — the comfort signal a plain temperature reading hides.

Days feeling ≥ 32°C
0
heat index over the day's high
Days feeling ≤ C
0
wind chill below the day's low

May sits comfortably in between — no days that feel dangerously hot or drop to a hard freeze once humidity and wind are folded in.

Siena weather by month

How May compares with the rest of the year at a glance. May is the 5th-warmest and 6th-wettest month here — the current month is highlighted below.

MonthHigh / Low (°C)Rainfall (mm)Wet daysSnow daysDaylight (hours)Travel score
Jan / 558.10.89.21.9
Feb10° / 658.41.210.22.5
Mar14° / 6690.511.64.2
Apr17° / 7911.3013.25.4
May22° / 11°7110.1014.56.7
Jun26° / 15°507.5015.17.4
Jul29° / 17°315014.96.5
Aug29° / 18°406.2013.86.3
Sep25° / 14°929012.37.1
Oct19° / 10°10910.4010.86.2
Nov14° / 12011.60.19.53.8
Dec10° / 79100.58.82.1

Cloud cover in May

ClearMostly clearPartly cloudyMostly cloudyOvercast

The sky is clear or mostly clear about 37% of the time in May.

Beyond those clear spells, partly cloudy skies cover about 19% of May, with mostly cloudy or overcast conditions the remaining 44%. Skies tend to open up as the month goes on.

0%25%50%75%100%151015202531
Clearer (%)Cloudier (%)
14852
24852
34951
44951
54951
65050
75050
85149
95149
105248
115248
125347
135347
145446
155446
165545
175545
185743
195842
205842
216040
226139
236139
246337
256337
266436
276436
286535
296535
306535
316436

Chance of precipitation in May

Any precipitation

Siena gets around 71 mm of rain over 10.1 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 33% and peaks near 41% on the wettest days. The odds ease toward the end of the month.

0%10%20%30%40%50%151015202531
Rain chance (%)
141
241
341
441
540
640
739
838
937
1037
1136
1235
1335
1434
1533
1632
1732
1831
1930
2030
2129
2229
2328
2428
2528
2628
2727
2827
2928
3028
3128

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 76% of days. It rarely turns muggy — the humid and sticky bands barely register.

0%25%50%75%100%151015202531
Dry (%)Comfortable (%)Humid (%)
19280
29190
390100
489110
588120
687130
786140
885150
984160
1083170
1182180
1282180
1381190
1480200
1580200
1679210
1778220
1877230
1975241
2074251
2173261
2272271
2369292
2468302
2565323
2663343
2760364
2857385
2954406
3052417
3149438

Wind in May

Winds average 8 km/h in May.

Across May, daily wind ranges from about 7 km/h on the calmest days to 8 km/h at its breeziest. It stays fairly steady from day to day.

0246810151015202531
Wind speed (km/h)Feels
18calm
28calm
38calm
48calm
58calm
68calm
78calm
88calm
98calm
108calm
118calm
128calm
138calm
148calm
158calm
168calm
178calm
188calm
198calm
208calm
218calm
228calm
238calm
248calm
257calm
267calm
277calm
287calm
297calm
307calm
317calm

Sunrise & sunset in May

DaylightNight

Daylight runs from about 13 h 54 min at the start of May to 14 h 54 min by month's end. The lit band spans sunrise to sunset each day.

Days grow by about 60 minutes over May. Sunrise moves from 5:15 AM to 4:44 AM, and sunset from 7:08 PM to 7:40 PM.

12 AM4 AM8 AM12 PM4 PM8 PM12 AM151015202531
Daylight (h)Sunrise (AM)Sunset (PM)
113.95:157:08
213.95:147:10
314.05:137:11
414.05:117:12
514.15:107:13
614.15:087:14
714.15:077:15
814.25:067:17
914.25:057:18
1014.35:037:19
1114.35:027:20
1214.35:017:21
1314.45:007:22
1414.44:597:23
1514.44:577:24
1614.54:567:25
1714.54:557:27
1814.64:547:28
1914.64:537:29
2014.64:527:30
2114.74:517:31
2214.74:517:32
2314.74:507:33
2414.74:497:34
2514.84:487:35
2614.84:477:36
2714.84:467:37
2814.94:467:38
2914.94:457:38
3014.94:447:39
3114.94:447:40

Solar energy in May

Daily solar energy (kWh/m²)

Average shortwave solar energy reaching the ground each day in May, about 6.1 kWh/m².

For context, solar energy here swings from a low near 1.43 kWh/m² to a high of 6.97 kWh/m² in July across the year — May's 6.1 kWh/m² sits near the top of that range.

0246151015202531
Solar energy (kWh/m²)Level
15.5Bright
25.5Bright
35.6Bright
45.6Bright
55.7Bright
65.7Bright
75.7Bright
85.8Bright
95.8Bright
105.9Bright
115.9Bright
125.9Bright
136.0Bright
146.0Intense
156.0Intense
166.1Intense
176.1Intense
186.2Intense
196.2Intense
206.2Intense
216.3Intense
226.3Intense
236.3Intense
246.3Intense
256.4Intense
266.4Intense
276.4Intense
286.4Intense
296.5Intense
306.5Intense
316.5Intense
Planning a trip in May

Is May a good time to visit Siena?

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

6.7
Sightseeing
3rd-best month of the year
4.4
Beach & pool
5th-best month of the year

May is a reasonable time to visit Siena for sightseeing.

What to pack for Siena in May

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

In May, Siena sees daytime highs around 22°C and nights near 11°C. Pack sun protection. Worth having: rain gear. About 10 days see rain.

sun protectionrain gear

UV index in Siena in May

LowModerateHighVery highExtreme

Clear-sky midday UV in May peaks 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 Siena peaks around July 14 at about 9 (very high) — sunscreen, a hat and midday shade are essential. It bottoms out near December 23 at about 1 (low).

The index reaches 3 or more — the level where the WHO recommends sun protection — in 8 months of the year.

025710JanFebMarAprMayJunJulAugSepOctNovDecLowModerateHighVery highHighModerateLowJul 14UV 9Dec 23UV 1
UV index (midday)Level
Jan1Low
Feb3Moderate
Mar5Moderate
Apr6High
May6High
Jun8Very high
Jul9Very high
Aug7Very high
Sep5High
Oct3Moderate
Nov2Moderate
Dec1Low

Air quality in Siena 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 Siena is worst in March — around 17 µg/m³ PM2.5 (moderate), and holds fairly steady the rest of the year.

Modeled monthly averages (CAMS reanalysis, 2015–2024).

01020JanFebMarAprMayJunJulAugSepOctNovDecModerateGoodModerateMar 2016 µg/m³Nov 1712 µg/m³
PM2.5 (µg/m³)Level
Jan14Moderate
Feb14Moderate
Mar17Moderate
Apr16Moderate
May15Moderate
Jun14Moderate
Jul12Good
Aug13Moderate
Sep12Moderate
Oct13Moderate
Nov12Good
Dec12Moderate
Location & terrain

Where is Siena?

Siena sits at 43.3°N, 11.3°E, 322 m above sea level, in Italy. The nearest listed city is Colle di Val d'Elsa, 20 km away.

Topography around Siena

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

Within 3 km, the terrain around Siena has only modest variations in elevation — a maximum elevation change of 199 m around an average of 283 m above sea level; within 16 km, significant variations in elevation — a maximum elevation change of 520 m; within 80 km, very significant variations in elevation — a maximum elevation change of 1,724 m.

The land around Siena is covered by trees (57%) and grassland (22%) within 3 km, trees (55%) and cropland (24%) within 16 km, and trees (62%) within 80 km.

3 km
199 m
16 km
520 m
80 km
1,724 m
treesshrubsgrasslandcroplandartificial surfaceswater
May weather nearby: Colle di Val d'Elsa 20 km · Poggibonsi 22 km · Montevarchi 30 km · San Giovanni Valdarno 32 km · Arezzo 47 km · Scandicci 50 km · Campo di Marte 51 km · Florence 52 km

Italy travel facts

Travel advisory
Level 2
Exercise Increased Caution
Power plugs
Type C / F / L
230 V · 50 Hz
Prices
≈ 69% of US
price level, 2025
GDP per capita
$43,309
2025
Happiness
6.6 / 10
World Happiness, 2025
Safe drinking water
97%
of population, 2024
Homicide rate
0.6
per 100k, 2023
Road deaths
5.3
per 100k/yr, 2019
Income group
High
World Bank
English
Moderate
EF EPI 513
Religion
Christian 81%unaffiliated 13%Muslim 5%other 1%

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 Siena (43.3182°, 11.3306°, elevation 322 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. 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).