Formia weather in September

In September, Formia sees average daytime highs of 24°C and overnight lows near 19°C, with 96 mm of rain across 8.3 wet days and about 12.3 hours of daylight. It is the 3rd-warmest and 6th-wettest month of the year here.

Highs ease over the month, from about 25°C in the first days to 22°C by the end. The sky is clear or mostly clear about 58% of the time in September, and the air most often feels humid.

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 Formia's 4th-clearest and 9th-windiest month. For the whole year in context, see Formia's year-round climate.

Daytime high
24°
3rd warmest
Overnight low
19°
10th coldest
Rainfall
96 mm
8.3 wet days
Daylight
12 h 18 min
5:52 AM – 6:08 PM
Cloud cover
40%
4th clearest
Wind
9 km/h
9th windiest
Solar energy
4.66 kWh/m²
Travel score
7.5
out of 10

Formia is chief town of the homonym municipality.

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 25°C in the first days to 22°C by the end.

A typical September day in Formia reaches about 24°C in the afternoon and slips back to 19°C overnight — a 5°C spread between the day's warmth and the night's chill. On most days the high lands between 21°C and 26°C. Set against its neighbours, September runs about 3°C cooler than August and about 4°C warmer than October.

15°20°25°30°151015202530
Avg high (°C)Avg low (°C)
12621
22621
32521
42520
52520
62520
72520
82520
92520
102420
112420
122420
132419
142419
152419
162419
172419
182319
192319
202319
212318
222318
232318
242318
252318
262218
272218
282218
292218
302217

Formia weather by month

How September compares with the rest of the year at a glance. September is the 3rd-warmest and 6th-wettest month here — the current month is highlighted below.

MonthHigh / Low (°C)Rainfall (mm)Wet daysDaylight (hours)Travel score
Jan12° / 10210.29.43.1
Feb12° / 999.810.33.2
Mar14° / 939.511.74.1
Apr16° / 11°8210.413.15.1
May20° / 15°537.214.37.0
Jun24° / 19°264.214.98.3
Jul26° / 22°142.814.78.5
Aug27° / 22°192.613.78.3
Sep24° / 19°968.312.37.5
Oct20° / 16°14610.410.96.5
Nov16° / 12°20213.89.74.7
Dec13° / 14612.29.13.5

Cloud cover in September

ClearMostly clearPartly cloudyMostly cloudyOvercast

The sky is clear or mostly clear about 58% of the time in September.

Beyond those clear spells, partly cloudy skies cover about 16% of September, with mostly cloudy or overcast conditions the remaining 27%. Skies tend to cloud over as the month goes on.

0%25%50%75%100%151015202530
Clearer (%)Cloudier (%)
18416
28317
38119
48119
58020
67822
77822
87723
97525
107525
117525
127327
137327
147327
157129
167129
177129
187030
197030
207030
217030
227030
237030
246931
256931
266931
276931
286832
296832
306832

Chance of precipitation in September

Any precipitation

Formia gets around 96 mm of rain over 8.3 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 28% and peaks near 31% on the wettest days. The odds climb toward the end of the month.

0%10%20%30%40%151015202530
Rain chance (%)
118
219
320
421
522
623
724
825
926
1027
1127
1228
1329
1429
1530
1630
1731
1831
1931
2031
2131
2231
2331
2430
2530
2630
2730
2830
2930
3031

Humidity in September

DryComfortableHumidMuggyOppressiveMiserable

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

By dew point, September lands in the humid band about 34% of days. Sticky, muggy-or-worse air turns up on roughly 33% of them.

0%25%50%75%100%151015202530
Dry (%)Comfortable (%)Humid (%)Muggy (%)Oppressive (%)
1411284314
2512294312
3513304210
451431419
561532417
661633406
761633395
861734394
961834383
1071835383
1171935372
1271935372
1382035361
1482135351
1582235341
1692335321
1792435311
18102535291
19112635271
20122735261
21122835241
22132935221
23142935211
24143036190
25153136170
26153237160
27153337140
28163437130
29163537120
30163638100

Wind in September

Winds average 9 km/h in September.

Across September, daily wind ranges from about 9 km/h on the calmest days to 9 km/h at its breeziest. It stays fairly steady from day to day.

051015151015202530
Wind speed (km/h)Feels
19calm
29calm
39calm
49calm
59calm
69calm
79calm
89calm
99calm
109calm
119calm
129calm
139calm
149calm
159calm
169calm
179calm
189calm
199calm
209calm
219calm
229calm
239calm
249calm
259calm
269calm
279calm
289calm
299calm
309calm

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 5:36 AM to 6:07 AM, and sunset from 6:34 PM to 5:43 PM.

12 AM4 AM8 AM12 PM4 PM8 PM12 AM151015202530
Daylight (h)Sunrise (AM)Sunset (PM)
113.05:366:34
212.95:376:33
312.95:386:31
412.85:396:29
512.85:406:27
612.75:416:26
712.75:426:24
812.65:436:22
912.65:456:20
1012.65:466:19
1112.55:476:17
1212.55:486:15
1312.45:496:13
1412.45:506:12
1512.35:516:10
1612.35:526:08
1712.25:536:06
1812.25:546:04
1912.15:556:03
2012.15:566:01
2112.05:575:59
2212.05:585:57
2311.95:595:56
2411.96:005:54
2511.86:015:52
2611.86:025:50
2711.86:035:48
2811.76:045:47
2911.76:055:45
3011.66:075:43

Solar energy in September

Daily solar energy (kWh/m²)

Average shortwave solar energy reaching the ground each day in September, about 4.66 kWh/m².

For context, solar energy here swings from a low near 1.71 kWh/m² to a high of 7.08 kWh/m² in July across the year — September's 4.66 kWh/m² falls in the middle.

0246151015202530
Solar energy (kWh/m²)Level
15.5Bright
25.4Bright
35.3Bright
45.3Bright
55.2Bright
65.2Bright
75.1Bright
85.0Bright
95.0Bright
104.9Bright
114.9Bright
124.8Bright
134.8Bright
144.7Bright
154.7Bright
164.6Bright
174.6Bright
184.5Bright
194.5Bright
204.4Bright
214.4Bright
224.3Bright
234.3Bright
244.2Bright
254.2Bright
264.1Bright
274.1Bright
284.0Bright
294.0Moderate
303.9Moderate
Planning a trip in September

Hazard calendar for Formia

In seasonPeak

In September, Formia sits inside its rainy season season. The full year is below, with each hazard's peak months called out.

Formia's rainy season runs September–March, when most of the year's rain falls.

Rainy season
Jan
Feb
Mar
Apr
May
Jun
Jul
Aug
Sep
Oct
Nov
Dec

Is September a good time to visit Formia?

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

7.5
Sightseeing
4th-best month of the year
6.1
Beach & pool
4th-best month of the year

September is one of the better times to visit Formia for general sightseeing. The water and warmth also suit a beach or pool day.

What to pack for Formia in September

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

In September, Formia sees daytime highs around 24°C and nights near 19°C. Worth packing: light clothes, rain gear and sun protection. About 8 days see rain.

light clothesrain gearsun protection

Sea temperature near Formia 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 15 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 28 to Nov 5 — 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
Sep24Warm
Oct22Refreshing
Nov19Cool
Dec17Cool

UV index in Formia 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 Formia peaks around July 16 at about 10 (very high) — sunscreen, a hat and midday shade are essential. It bottoms out near December 21 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 highHighModerateLowJul 16UV 10Dec 21UV 1
UV index (midday)Level
Jan2Low
Feb3Moderate
Mar5Moderate
Apr4Moderate
May7High
Jun9Very high
Jul10Very high
Aug8Very high
Sep6High
Oct4Moderate
Nov2Moderate
Dec1Low
Location & terrain

Where is Formia?

Formia sits at 41.3°N, 13.6°E, 19 m above sea level, in Italy. The nearest listed city is Gaeta, 6.0 km away.

Topography around Formia

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

Within 3 km, the terrain around Formia has large variations in elevation — a maximum elevation change of 826 m around an average of 111 m above sea level; within 16 km, very significant variations in elevation — a maximum elevation change of 1,526 m; within 80 km, very significant variations in elevation — a maximum elevation change of 2,266 m.

The land around Formia is covered by water (45%) within 3 km, water (42%) and trees (32%) within 16 km, and water (41%) and trees (36%) within 80 km.

3 km
826 m
16 km
1,526 m
80 km
2,266 m
treesshrubsgrasslandcroplandartificial surfaceswater
September weather nearby: Gaeta 6.0 km · Minturno 11 km · Fondi 19 km · Mondragone 28 km · Terracina 31 km · Cassino 31 km · Castel Volturno 37 km · Frosinone 48 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 Formia (41.2563°, 13.6089°, elevation 19 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. Topography is sampled from the Copernicus DEM GLO-90 elevation model (© ESA/Airbus) and ESA WorldCover 2021 land cover (CC BY 4.0).