Colleferro weather in September

In September, Colleferro sees average daytime highs of 24°C and overnight lows near 14°C, with 103 mm of rain across 11.3 wet days and about 12.3 hours of daylight. It is the 4th-warmest and 6th-wettest month of the year here.

Highs ease over the month, from about 26°C in the first days to 22°C by the end. The sky is clear or mostly clear about 47% of the time in September, and the air most often feels comfortable.

Daylight stretches from about 13 hours at the start of September to 11 h 36 min by month's end. Set against the rest of the year, September is Colleferro's 4th-clearest and 12th-windiest month. For the whole year in context, see Colleferro's year-round climate.

Daytime high
24°
4th warmest
Overnight low
14°
9th coldest
Rainfall
103 mm
11.3 wet days
Daylight
12 h 18 min
5:54 AM – 6:11 PM
Cloud cover
46%
4th clearest
Wind
6 km/h
12th windiest
Solar energy
4.49 kWh/m²
Travel score
6.8
out of 10

Colleferro is chief town of the homonym municipality.

Air quality
Elevated
PM2.5 20.2 µg/m³ · 2019

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

Temperature in September

Average highAverage lowShaded bands: 10–90% of days

Highs ease over the month, from about 26°C in the first days to 22°C by the end.

A typical September day in Colleferro reaches about 24°C in the afternoon and slips back to 14°C overnight — a 10°C spread between the day's warmth and the night's chill. On most days the high lands between 20°C and 28°C. Set against its neighbours, September runs about 5°C cooler than August and about 5°C warmer than October.

10°20°30°151015202530
Avg high (°C)Avg low (°C)
12716
22616
32616
42615
52615
62615
72515
82515
92515
102515
112515
122514
132414
142414
152414
162414
172414
182414
192314
202313
212313
222313
232313
242313
252213
262213
272213
282212
292212
302212

How September really feels in Colleferro

Once humidity and wind are folded in, September 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

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

Colleferro weather by month

How September compares with the rest of the year at a glance. September is the 4th-warmest and 6th-wettest month here — the current month is highlighted below.

MonthHigh / Low (°C)Rainfall (mm)Wet daysSnow daysDaylight (hours)Travel score
Jan10° / 869.519.32.1
Feb11° / 9210.11.310.32.5
Mar14° / 10511.20.911.73.9
Apr17° / 11914.10.313.14.8
May21° / 11°10012.1014.36.3
Jun25° / 15°689.30157.2
Jul29° / 17°436.5014.76.8
Aug29° / 17°427.5013.76.4
Sep24° / 14°10311.3012.36.8
Oct20° / 10°13111.3010.96.2
Nov14° / 15713.20.19.64.0
Dec10° / 12610.70.592.5

Cloud cover in September

ClearMostly clearPartly cloudyMostly cloudyOvercast

The sky is clear or mostly clear about 47% of the time in September.

Beyond those clear spells, partly cloudy skies cover about 21% of September, with mostly cloudy or overcast conditions the remaining 32%. Skies tend to cloud over as the month goes on.

0%25%50%75%100%151015202530
Clearer (%)Cloudier (%)
17921
27822
37624
47624
57426
67426
77327
87129
97129
107030
116931
126931
136733
146733
156634
166634
176634
186535
196436
206436
216436
226337
236337
246337
256337
266238
276238
286238
296238
306040

Chance of precipitation in September

Any precipitation

Colleferro gets around 103 mm of rain over 11.3 wet days in September. The line is the day-by-day chance of measurable precipitation.

Day to day, the chance of measurable rain averages around 38% and peaks near 40% on the wettest days.

0%10%20%30%40%50%151015202530
Rain chance (%)
134
235
335
436
537
637
737
838
938
1038
1138
1238
1339
1439
1539
1639
1740
1840
1940
2040
2139
2239
2339
2438
2538
2638
2737
2837
2937
3037

Humidity in September

DryComfortableHumidMuggyOppressiveMiserable

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

By dew point, September lands in the comfortable band about 42% of days. It rarely turns muggy — the humid and sticky bands barely register.

0%25%50%75%100%151015202530
Dry (%)Comfortable (%)Humid (%)Muggy (%)
11836407
21937386
32038366
42140355
52141335
62242324
72343314
82443303
92444293
102544283
112645272
122645272
132745262
142845262
152945252
163045242
173145232
183344222
193444211
203643201
213842191
224041181
234241171
244340161
254540151
264639141
274739130
284939120
295138110
305138110

Wind in September

Winds average 6 km/h in September, the calmest month.

Across September, daily wind ranges from about 6 km/h on the calmest days to 6 km/h at its breeziest. It stays fairly steady from day to day.

0246810151015202530
Wind speed (km/h)Feels
16calm
26calm
36calm
46calm
56calm
66calm
76calm
86calm
96calm
106calm
116calm
126calm
136calm
146calm
156calm
166calm
176calm
186calm
196calm
206calm
216calm
226calm
236calm
246calm
256calm
266calm
276calm
286calm
296calm
306calm

Sunrise & sunset in September

DaylightNight

Daylight runs from about 13 hours at the start of September to 11 h 36 min by month's end. The lit band spans sunrise to sunset each day.

Days shrink by about 84 minutes over September. Sunrise moves from 5:38 AM to 6:09 AM, and sunset from 6:37 PM to 5:45 PM.

12 AM4 AM8 AM12 PM4 PM8 PM12 AM151015202530
Daylight (h)Sunrise (AM)Sunset (PM)
113.05:386:37
212.95:396:35
312.95:406:34
412.85:416:32
512.85:426:30
612.85:436:28
712.75:456:27
812.75:466:25
912.65:476:23
1012.65:486:21
1112.55:496:20
1212.55:506:18
1312.45:516:16
1412.45:526:14
1512.35:536:12
1612.35:546:11
1712.25:556:09
1812.25:566:07
1912.15:576:05
2012.15:586:03
2112.05:596:02
2212.06:006:00
2311.96:025:58
2411.96:035:56
2511.86:045:54
2611.86:055:53
2711.76:065:51
2811.76:075:49
2911.76:085:47
3011.66:095:45

Solar energy in September

Daily solar energy (kWh/m²)

Average shortwave solar energy reaching the ground each day in September, about 4.49 kWh/m².

For context, solar energy here swings from a low near 1.65 kWh/m² to a high of 7 kWh/m² in July across the year — September's 4.49 kWh/m² falls in the middle.

0246151015202530
Solar energy (kWh/m²)Level
15.3Bright
25.3Bright
35.2Bright
45.1Bright
55.1Bright
65.0Bright
75.0Bright
84.9Bright
94.8Bright
104.8Bright
114.7Bright
124.7Bright
134.6Bright
144.5Bright
154.5Bright
164.4Bright
174.4Bright
184.3Bright
194.3Bright
204.2Bright
214.2Bright
224.1Bright
234.1Bright
244.0Bright
254.0Moderate
264.0Moderate
273.9Moderate
283.9Moderate
293.8Moderate
303.8Moderate
Planning a trip in September

Is September a good time to visit Colleferro?

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

6.8
Sightseeing
2nd-best month of the year
5.7
Beach & pool
4th-best month of the year

September is a reasonable time to visit Colleferro for sightseeing.

What to pack for Colleferro in September

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

In September, Colleferro sees daytime highs around 24°C and nights near 14°C. Worth packing: light clothes and rain gear. About 11 days see rain.

light clothesrain gear

Sea temperature near Colleferro in September

The nearest coast averages about 24°C in September — the other half of the beach question. The full-year curve and swim-comfort zones are below.

The sea at the nearest coast (about 41 km away) is warmest in August at about 26°C and coldest in February near 14°C.

It's comfortable for a long swim from May 29 to Nov 4 — about 5.3 months when the water holds above 20°C.

15°20°25°JanFebMarAprMayJunJulAugSepOctNovDecbracingcoolrefreshingwarmtropicalcomfortable to swim
Sea temperature (°C)Comfort
Jan15Bracing
Feb14Bracing
Mar14Bracing
Apr16Cool
May19Cool
Jun22Refreshing
Jul25Warm
Aug26Warm
Sep24Refreshing
Oct22Refreshing
Nov19Cool
Dec17Cool

UV index in Colleferro in September

LowModerateHighVery highExtreme

Clear-sky midday UV in September 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 Colleferro peaks around July 15 at about 10 (very high) — sunscreen, a hat and midday shade are essential. It bottoms out near December 22 at about 1 (low).

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

025710JanFebMarAprMayJunJulAugSepOctNovDecLowModerateVery highModerateLowJul 15UV 10Dec 22UV 1
UV index (midday)Level
Jan1Low
Feb3Moderate
Mar5Moderate
Apr4Moderate
May7High
Jun9Very high
Jul10Very high
Aug8Very high
Sep6High
Oct4Moderate
Nov2Moderate
Dec1Low

Air quality in Colleferro in September

GoodModeratePoorUnhealthyVery unhealthy

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

Air quality in Colleferro is worst in April — around 25 µg/m³ PM2.5 (moderate), and holds fairly steady the rest of the year.

Seasonal pattern from CAMS reanalysis, scaled to Colleferro's WHO annual average of 20.2 µg/m³.

0102030JanFebMarAprMayJunJulAugSepOctNovDecModerateApr 1125 µg/m³Sep 1817 µg/m³
PM2.5 (µg/m³)Level
Jan21Moderate
Feb22Moderate
Mar25Moderate
Apr25Moderate
May22Moderate
Jun20Moderate
Jul17Moderate
Aug19Moderate
Sep17Moderate
Oct18Moderate
Nov17Moderate
Dec19Moderate
Location & terrain

Where is Colleferro?

Colleferro sits at 41.7°N, 13.0°E, 218 m above sea level, in Italy. The nearest listed city is Velletri, 19 km away.

Topography around Colleferro

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

Within 3 km, the terrain around Colleferro has significant variations in elevation — a maximum elevation change of 471 m around an average of 280 m above sea level; within 16 km, very significant variations in elevation — a maximum elevation change of 1,328 m; within 80 km, extreme variations in elevation — a maximum elevation change of 2,452 m.

The land around Colleferro is covered by trees (44%) and cropland (26%) within 3 km, trees (68%) within 16 km, and trees (45%) and water (24%) within 80 km.

3 km
471 m
16 km
1,328 m
80 km
2,452 m
treesshrubsgrasslandcroplandartificial surfacesbare terrainwater
September weather nearby: Velletri 19 km · Cisterna di Latina 21 km · Rocca di Papa 25 km · Sezze 26 km · Genzano di Roma 26 km · Ariccia 28 km · Grottaferrata 28 km · Frascati 28 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 Colleferro (41.7272°, 13.0048°, elevation 218 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).