Spa weather in September

In September, Spa sees average daytime highs of 18°C and overnight lows near 10°C, with 74 mm of rain across 11.9 wet days and about 12.4 hours of daylight. It is the 4th-warmest and 11th-wettest month of the year here.

Highs ease over the month, from about 19°C in the first days to 16°C by the end. The sky is clear or mostly clear about 19% of the time in September, and the air most often feels dry.

Daylight stretches from about 13 h 18 min at the start of September to 11 h 30 min by month's end. Set against the rest of the year, September is Spa's 3rd-clearest and 8th-windiest month. For the whole year in context, see Spa's year-round climate.

Daytime high
18°
4th warmest
Overnight low
10°
9th coldest
Rainfall
74 mm
11.9 wet days
Daylight
12 h 24 min
6:20 AM – 6:42 PM
Cloud cover
66%
3rd clearest
Wind
13 km/h
8th windiest
Solar energy
3.1 kWh/m²
Travel score
5.2
out of 10

Spa is town in Spa municipality, Belgium.

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 19°C in the first days to 16°C by the end.

A typical September day in Spa reaches about 18°C in the afternoon and slips back to 10°C overnight — a 8°C spread between the day's warmth and the night's chill. On most days the high lands between 13°C and 23°C. Set against its neighbours, September runs about 4°C cooler than August and about 4°C warmer than October.

10°15°20°25°151015202530
Avg high (°C)Avg low (°C)
11911
21911
31911
41911
51911
61911
71911
81811
91811
101811
111811
121810
131810
141810
151810
161810
171710
181710
191710
201710
21179
22179
23179
24179
25169
26169
27169
28169
29169
30169

How September really feels in Spa

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.

Spa weather by month

How September compares with the rest of the year at a glance. September is the 4th-warmest and 11th-wettest month here — the current month is highlighted below.

MonthHigh / Low (°C)Rainfall (mm)Wet daysSnow daysDaylight (hours)Travel score
Jan / 9814.94.58.30.0
Feb / 8713.75.49.70.1
Mar / 8715.13.611.51.5
Apr13° / 6312.60.613.53.3
May17° / 7414015.24.7
Jun20° / 11°8413.7016.15.5
Jul22° / 13°8914.6015.85.9
Aug21° / 13°8913.6014.35.9
Sep18° / 10°7411.9012.45.2
Oct13° / 7613.2010.43.4
Nov / 8214.41.78.71.2
Dec / 10315.84.87.90.0

Cloud cover in September

ClearMostly clearPartly cloudyMostly cloudyOvercast

The sky is clear or mostly clear about 19% of the time in September.

Beyond those clear spells, partly cloudy skies cover about 15% of September, with mostly cloudy or overcast conditions the remaining 66%.

0%25%50%75%100%151015202530
Clearer (%)Cloudier (%)
13565
23565
33565
43565
53565
63565
73565
83565
93565
103565
113466
123565
133565
143565
153664
163664
173664
183565
193565
203565
213664
223565
233565
243565
253466
263367
273268
283169
293070
302971

Chance of precipitation in September

Any precipitation

Spa gets around 74 mm of rain over 11.9 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 41% and peaks near 47% on the wettest days.

0%20%40%60%151015202530
Rain chance (%)
142
241
341
440
540
640
740
839
939
1039
1139
1239
1339
1439
1538
1638
1738
1839
1939
2039
2140
2241
2341
2442
2543
2644
2744
2845
2946
3047

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 82% of days. It rarely turns muggy — the humid and sticky bands barely register.

0%25%50%75%100%151015202530
Dry (%)Comfortable (%)Humid (%)Muggy (%)
1682651
2682651
3712540
4712540
5722440
6732430
7742330
8752230
9752230
10762130
11772030
12791920
13811720
14821620
15831520
16841420
17851320
18861220
19881110
20881110
21891010
22891010
23891010
2490910
2590910
2691900
2791900
2891900
2991900
3091900

Wind in September

Winds average 13 km/h in September.

Across September, daily wind ranges from about 13 km/h on the calmest days to 14 km/h at its breeziest. It stays fairly steady from day to day.

05101520151015202530
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
2413light breeze
2513light breeze
2614light breeze
2714light breeze
2814light breeze
2914light breeze
3014light breeze

Sunrise & sunset in September

DaylightNight

Daylight runs from about 13 h 18 min at the start of September to 11 h 30 min by month's end. The lit band spans sunrise to sunset each day.

Days shrink by about 108 minutes over September. Sunrise moves from 5:56 AM to 6:42 AM, and sunset from 7:16 PM to 6:10 PM.

12 AM4 AM8 AM12 PM4 PM8 PM12 AM151015202530
Daylight (h)Sunrise (AM)Sunset (PM)
113.35:567:16
213.35:587:14
313.25:597:12
413.16:017:10
513.16:027:07
613.06:047:05
713.06:057:03
812.96:077:01
912.86:096:58
1012.86:106:56
1112.76:126:54
1212.66:136:51
1312.66:156:49
1412.56:166:47
1512.46:186:44
1612.46:206:42
1712.36:216:40
1812.26:236:37
1912.26:246:35
2012.16:266:33
2112.06:286:30
2212.06:296:28
2311.96:316:26
2411.96:326:24
2511.86:346:21
2611.76:366:19
2711.76:376:17
2811.66:396:14
2911.56:406:12
3011.56:426:10

Solar energy in September

Daily solar energy (kWh/m²)

Average shortwave solar energy reaching the ground each day in September, about 3.1 kWh/m².

For context, solar energy here swings from a low near 0.64 kWh/m² to a high of 5.32 kWh/m² in June across the year — September's 3.1 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
143.2Moderate
153.1Moderate
163.1Moderate
173.0Moderate
183.0Moderate
193.0Moderate
202.9Moderate
212.9Moderate
222.8Moderate
232.8Moderate
242.7Moderate
252.7Moderate
262.6Moderate
272.6Moderate
282.5Moderate
292.5Moderate
302.4Moderate
Planning a trip in September

Is September a good time to visit Spa?

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
1.5
Beach & pool
4th-best month of the year

September is a reasonable time to visit Spa for sightseeing.

What to pack for Spa in September

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

In September, Spa sees daytime highs around 18°C and nights near 10°C. Worth packing: rain gear. About 12 days see rain.

rain gear

UV index in Spa 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 Spa peaks around July 16 at about 7 (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 7 months of the year.

025710JanFebMarAprMayJunJulAugSepOctNovDecLowModerateHighModerateLowJul 16UV 7Jan 1UV 1
UV index (midday)Level
Jan1Low
Feb1Low
Mar3Moderate
Apr4Moderate
May6High
Jun6High
Jul7High
Aug6High
Sep4Moderate
Oct3Moderate
Nov1Low
Dec1Low

Air quality in Spa 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 Spa is worst in April — around 18 µg/m³ PM2.5 (moderate), about 1.7× the cleanest month (November, 11 µg/m³).

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

01020JanFebMarAprMayJunJulAugSepOctNovDecModerateGoodApr 1218 µg/m³Nov 2211 µg/m³
PM2.5 (µg/m³)Level
Jan14Moderate
Feb13Moderate
Mar17Moderate
Apr18Moderate
May15Moderate
Jun14Moderate
Jul13Moderate
Aug14Moderate
Sep13Moderate
Oct12Good
Nov11Good
Dec11Good
Location & terrain

Where is Spa?

Spa sits at 50.5°N, 5.9°E, 0 m above sea level, in Belgium. The nearest listed city is Heusy, 10 km away.

SoumagneHerveFléronChaudfontaineEupenGrivegnée

Topography around Spa

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

Within 3 km, the terrain around Spa has significant variations in elevation — a maximum elevation change of 353 m around an average of 369 m above sea level; within 16 km, large variations in elevation — a maximum elevation change of 615 m; within 80 km, large variations in elevation — a maximum elevation change of 1,001 m.

The land around Spa is covered by trees (79%) within 3 km, trees (61%) and grassland (33%) within 16 km, and trees (43%), grassland (26%) and cropland (24%) within 80 km.

3 km
353 m
16 km
615 m
80 km
1,001 m
treesgrasslandcroplandartificial surfaceswater
September weather nearby: Heusy 10 km · Verviers 12 km · Soumagne 17 km · Herve 18 km · Fléron 20 km · Chaudfontaine 20 km · Eupen 20 km · Grivegnée 24 km

Belgium travel facts

Travel advisory
Level 2
Exercise Increased Caution
Power plugs
Type C / E
230 V · 50 Hz
Prices
≈ 81% of US
price level, 2025
GDP per capita
$60,750
2025
Happiness
6.9 / 10
World Happiness, 2025
Safe drinking water
100%
of population, 2024
Homicide rate
1.1
per 100k, 2021
Road deaths
5.8
per 100k/yr, 2019
Income group
High
World Bank
English
Very high
EF EPI 608
Religion
Roman Catholic 57%nonbeliever/agnostic 20%atheist 9%Muslim 7%

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 Spa (50.4838°, 5.8667°, 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. 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).