Caerphilly weather in September

In September, Caerphilly sees average daytime highs of 17°C and overnight lows near 11°C, with 74 mm of rain across 11 wet days and about 12.4 hours of daylight. It is the 4th-warmest and 6th-wettest month of the year here.

Highs ease over the month, from about 18°C in the first days to 16°C by the end. The sky is clear or mostly clear about 15% of the time in September, and the air most often feels dry.

Daylight stretches from about 13 h 24 min at the start of September to 11 h 24 min by month's end. Set against the rest of the year, September is Caerphilly's 6th-clearest and 9th-windiest month. For the whole year in context, see Caerphilly's year-round climate.

Daytime high
17°
4th warmest
Overnight low
11°
9th coldest
Rainfall
74 mm
11 wet days
Daylight
12 h 24 min
5:56 AM – 6:19 PM
Cloud cover
70%
6th clearest
Wind
16 km/h
9th windiest
Solar energy
3.03 kWh/m²
Travel score
5.2
out of 10

Caerphilly is town and community in Wales.

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 18°C in the first days to 16°C by the end.

A typical September day in Caerphilly reaches about 17°C in the afternoon and slips back to 11°C overnight — a 6°C spread between the day's warmth and the night's chill. On most days the high lands between 15°C and 20°C. Set against its neighbours, September runs about 2°C cooler than August and about 3°C warmer than October.

10°15°20°25°151015202530
Avg high (°C)Avg low (°C)
11812
21812
31812
41812
51812
61812
71812
81812
91812
101812
111812
121812
131712
141712
151711
161711
171711
181711
191711
201711
211711
221711
231611
241611
251611
261611
271611
281611
291611
301611

How September really feels in Caerphilly

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.

Caerphilly 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
Jan / 9514.50.98.11.0
Feb / 7411.20.99.61.1
Mar / 6811.70.511.51.9
Apr12° / 7011.60.113.63.0
May15° / 7312.3015.34.2
Jun17° / 12°7111016.35.3
Jul19° / 13°7411.7015.95.8
Aug19° / 13°8712.3014.45.7
Sep17° / 11°7411012.45.2
Oct14° / 10614010.43.5
Nov10° / 10214.50.18.62.1
Dec / 10713.70.67.71.2

Cloud cover in September

ClearMostly clearPartly cloudyMostly cloudyOvercast

The sky is clear or mostly clear about 15% 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 69%.

0%25%50%75%100%151015202530
Clearer (%)Cloudier (%)
13268
23268
33268
43268
53169
63169
73169
83169
93169
103070
113070
123070
133070
143169
153169
163070
173169
183169
193169
203169
213169
223169
233169
243070
253070
263070
273070
283070
293070
302872

Chance of precipitation in September

Any precipitation

Caerphilly gets around 74 mm of rain over 11 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 37% and peaks near 44% on the wettest days. The odds climb toward the end of the month.

0%10%20%30%40%50%151015202530
Rain chance (%)
132
232
332
432
532
632
733
833
933
1034
1134
1235
1335
1436
1536
1636
1737
1837
1938
2038
2139
2240
2341
2441
2542
2643
2743
2843
2944
3044

Humidity in September

DryComfortableHumidMuggyOppressiveMiserable

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

By dew point, September lands in the dry band about 73% of days. It rarely turns muggy — the humid and sticky bands barely register.

0%25%50%75%100%151015202530
Dry (%)Comfortable (%)Humid (%)
163334
264324
364324
465314
566304
666304
767294
868284
969274
1070264
1172253
1272253
1373243
1475232
1575232
1676222
1776222
1877221
1977221
2077221
2177221
2277221
2377221
2479210
2579210
2680200
2780200
2881190
2982180
3083170

Wind in September

Winds average 16 km/h in September.

Across September, daily wind ranges from about 15 km/h on the calmest days to 17 km/h at its breeziest. It stays fairly steady from day to day.

05101520151015202530
Wind speed (km/h)Feels
115light breeze
215light breeze
315light breeze
415light breeze
515light breeze
615light breeze
716light breeze
816light breeze
916light breeze
1016light breeze
1116light breeze
1216light breeze
1316light breeze
1416light breeze
1516light breeze
1616light breeze
1716light breeze
1816light breeze
1916light breeze
2016light breeze
2116light breeze
2216light breeze
2316light breeze
2416light breeze
2516light breeze
2616light breeze
2716light breeze
2817light breeze
2917light breeze
3017light breeze

Sunrise & sunset in September

DaylightNight

Daylight runs from about 13 h 24 min at the start of September to 11 h 24 min by month's end. The lit band spans sunrise to sunset each day.

Days shrink by about 120 minutes over September. Sunrise moves from 5:31 AM to 6:19 AM, and sunset from 6:54 PM to 5:45 PM.

12 AM4 AM8 AM12 PM4 PM8 PM12 AM151015202530
Daylight (h)Sunrise (AM)Sunset (PM)
113.45:316:54
213.35:326:52
313.35:346:50
413.25:366:47
513.15:376:45
613.15:396:43
713.05:416:40
812.95:426:38
912.95:446:36
1012.85:466:33
1112.75:476:31
1212.75:496:28
1312.65:516:26
1412.55:526:24
1512.55:546:21
1612.45:566:19
1712.35:576:16
1812.35:596:14
1912.26:006:12
2012.16:026:09
2112.16:046:07
2212.06:056:04
2311.96:076:02
2411.86:096:00
2511.86:115:57
2611.76:125:55
2711.66:145:53
2811.66:165:50
2911.56:175:48
3011.46:195:45

Solar energy in September

Daily solar energy (kWh/m²)

Average shortwave solar energy reaching the ground each day in September, about 3.03 kWh/m².

For context, solar energy here swings from a low near 0.65 kWh/m² to a high of 5.28 kWh/m² in June across the year — September's 3.03 kWh/m² falls in the middle.

01234151015202530
Solar energy (kWh/m²)Level
13.6Moderate
23.6Moderate
33.6Moderate
43.5Moderate
53.5Moderate
63.5Moderate
73.4Moderate
83.4Moderate
93.3Moderate
103.3Moderate
113.3Moderate
123.2Moderate
133.2Moderate
143.1Moderate
153.1Moderate
163.0Moderate
173.0Moderate
182.9Moderate
192.9Moderate
202.8Moderate
212.8Moderate
222.7Moderate
232.7Moderate
242.6Moderate
252.6Moderate
262.5Moderate
272.5Moderate
282.5Moderate
292.4Moderate
302.4Moderate
Planning a trip in September

Is September a good time to visit Caerphilly?

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

5.2
Sightseeing
4th-best month of the year
1.3
Beach & pool
4th-best month of the year

September is a reasonable time to visit Caerphilly for sightseeing.

What to pack for Caerphilly in September

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

In September, Caerphilly sees daytime highs around 17°C and nights near 11°C. Worth packing: rain gear. About 11 days see rain.

rain gear

Sea temperature near Caerphilly in September

The nearest coast averages about 17°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 23 km away) is warmest in August at about 18°C and coldest in February near 7°C.

The water stays below 20°C all year — cool enough that most swimmers want a wetsuit.

5°10°15°20°JanFebMarAprMayJunJulAugSepOctNovDecbracingcoolrefreshing
Sea temperature (°C)Comfort
Jan8Bracing
Feb7Bracing
Mar8Bracing
Apr9Bracing
May12Bracing
Jun15Cool
Jul17Cool
Aug18Cool
Sep17Cool
Oct15Bracing
Nov12Bracing
Dec9Bracing

UV index in Caerphilly in September

LowModerateHighVery highExtreme

Clear-sky midday UV in September peaks around 4 — enough to warrant sun protection. The full-year curve, shaded by WHO exposure level, is below.

Under clear skies, the midday UV index in Caerphilly peaks around August 13 at about 6 (high) — sunscreen and a hat are worth it in the middle of the day. 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 6 months of the year.

025710JanFebMarAprMayJunJulAugSepOctNovDecLowModerateHighModerateLowAug 13UV 6Jan 1UV 1
UV index (midday)Level
Jan1Low
Feb1Low
Mar3Moderate
Apr4Moderate
May6High
Jun6High
Jul6High
Aug7High
Sep4Moderate
Oct2Moderate
Nov1Low
Dec1Low
Location & terrain

Where is Caerphilly?

Caerphilly sits at 51.6°N, 3.2°W, 94 m above sea level, in United Kingdom. The nearest listed city is Risca, 9.0 km away.

Topography around Caerphilly

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

Within 3 km, the terrain around Caerphilly has only modest variations in elevation — a maximum elevation change of 222 m around an average of 142 m above sea level; within 16 km, significant variations in elevation — a maximum elevation change of 473 m; within 80 km, large variations in elevation — a maximum elevation change of 864 m.

The land around Caerphilly is covered by trees (50%), grassland (29%) and artificial surfaces (20%) within 3 km, grassland (39%) and trees (38%) within 16 km, and grassland (51%) within 80 km.

3 km
222 m
16 km
473 m
80 km
864 m
treesgrasslandcroplandartificial surfaceswater
September weather nearby: Risca 9.0 km · Pontypridd 9.0 km · Gelligaer 10 km · Blackwood 10 km · Cardiff 11 km · Newport 15 km · Penarth 15 km · Cwmbran 16 km

United Kingdom travel facts

Travel advisory
Level 2
Exercise Increased Caution
Power plugs
Type D / G / M
230 V · 50 Hz
Prices
≈ 89% of US
price level, 2025
GDP per capita
$57,602
2025
Happiness
6.7 / 10
World Happiness, 2025
Safe drinking water
100%
of population, 2024
Homicide rate
1.1
per 100k, 2021
Road deaths
3.2
per 100k/yr, 2019
Income group
High
World Bank
Religion
Christian 60%none 26%Muslim 4%other 2%

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 Caerphilly (51.5745°, -3.218°, elevation 94 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).