Sint-Niklaas weather in September

In September, Sint-Niklaas sees average daytime highs of 19°C and overnight lows near 12°C, with 57 mm of rain across 10.3 wet days and about 12.4 hours of daylight. It is the 4th-warmest and 9th-wettest month of the year here.

Highs ease over the month, from about 20°C in the first days to 17°C by the end. The sky is clear or mostly clear about 18% 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 Sint-Niklaas's 3rd-clearest and 9th-windiest month. For the whole year in context, see Sint-Niklaas's year-round climate.

Daytime high
19°
4th warmest
Overnight low
12°
9th coldest
Rainfall
57 mm
10.3 wet days
Daylight
12 h 24 min
6:26 AM – 6:49 PM
Cloud cover
66%
3rd clearest
Wind
13 km/h
9th windiest
Solar energy
3.05 kWh/m²
Travel score
5.9
out of 10

Sint-Niklaas is town in Sint-Niklaas 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 20°C in the first days to 17°C by the end.

A typical September day in Sint-Niklaas reaches about 19°C in the afternoon and slips back to 12°C overnight — a 7°C spread between the day's warmth and the night's chill. On most days the high lands between 15°C and 23°C. Set against its neighbours, September runs about 3°C cooler than August and about 4°C warmer than October.

10°15°20°25°30°151015202530
Avg high (°C)Avg low (°C)
12113
22013
32013
42013
52013
62013
72013
82013
92012
102012
112012
121912
131912
141912
151912
161912
171912
181912
191912
201911
211811
221811
231811
241811
251811
261811
271811
281711
291711
301711

How September really feels in Sint-Niklaas

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.

Sint-Niklaas weather by month

How September compares with the rest of the year at a glance. September is the 4th-warmest and 9th-wettest month here — the current month is highlighted below.

MonthHigh / Low (°C)Rainfall (mm)Wet daysSnow daysDaylight (hours)Travel score
Jan / 6211.80.98.20.4
Feb / 5410.81.29.60.8
Mar10° / 53110.611.52.3
Apr14° / 4710.8013.54.0
May18° / 10°6111.9015.35.4
Jun20° / 13°6611.2016.26.0
Jul22° / 15°7512.2015.96.3
Aug22° / 14°7312.2014.46.3
Sep19° / 12°5710.3012.45.9
Oct15° / 5911.3010.44.1
Nov10° / 6311.90.48.72.0
Dec / 7213.41.17.70.7

Cloud cover in September

ClearMostly clearPartly cloudyMostly cloudyOvercast

The sky is clear or mostly clear about 18% of the time in September.

Beyond those clear spells, partly cloudy skies cover about 18% of September, with mostly cloudy or overcast conditions the remaining 64%.

0%25%50%75%100%151015202530
Clearer (%)Cloudier (%)
13664
23664
33664
43664
53664
63664
73664
83664
93664
103664
113664
123664
133763
143763
153763
163862
173763
183763
193763
203763
213664
223664
233664
243565
253565
263367
273268
283169
293169
302872

Chance of precipitation in September

Any precipitation

Sint-Niklaas gets around 57 mm of rain over 10.3 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 35% and peaks near 40% on the wettest days.

0%10%20%30%40%50%151015202530
Rain chance (%)
134
233
333
432
532
632
732
833
933
1033
1133
1234
1334
1434
1534
1634
1734
1835
1935
2035
2135
2236
2336
2436
2537
2637
2738
2839
2939
3040

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 65% of days. It rarely turns muggy — the humid and sticky bands barely register.

0%25%50%75%100%151015202530
Dry (%)Comfortable (%)Humid (%)Muggy (%)
15035132
25334121
35433121
45532121
55631121
65730121
75829121
85929120
96028120
106127120
116227110
126326110
136525100
14662590
15672580
16692470
17692470
18702460
19712450
20712540
21712540
22722530
23712630
24722620
25722620
26722620
27732610
28742510
29742510
30752410

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
2613light breeze
2713light breeze
2813light breeze
2914light breeze
3014light 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 6:02 AM to 6:49 AM, and sunset from 7:24 PM to 6:16 PM.

12 AM4 AM8 AM12 PM4 PM8 PM12 AM151015202530
Daylight (h)Sunrise (AM)Sunset (PM)
113.46:027:24
213.36:047:22
313.26:057:20
413.26:077:17
513.16:087:15
613.06:107:13
713.06:127:10
812.96:137:08
912.86:157:06
1012.86:167:03
1112.76:187:01
1212.76:206:59
1312.66:216:56
1412.56:236:54
1512.56:256:52
1612.46:266:49
1712.36:286:47
1812.36:296:45
1912.26:316:42
2012.16:336:40
2112.16:346:37
2212.06:366:35
2311.96:386:33
2411.86:396:30
2511.86:416:28
2611.76:436:26
2711.66:446:23
2811.66:466:21
2911.56:486:19
3011.46:496:16

Solar energy in September

Daily solar energy (kWh/m²)

Average shortwave solar energy reaching the ground each day in September, about 3.05 kWh/m².

For context, solar energy here swings from a low near 0.62 kWh/m² to a high of 5.26 kWh/m² in June across the year — September's 3.05 kWh/m² falls in the middle.

01234151015202530
Solar energy (kWh/m²)Level
13.6Moderate
23.6Moderate
33.5Moderate
43.5Moderate
53.5Moderate
63.4Moderate
73.4Moderate
83.3Moderate
93.3Moderate
103.3Moderate
113.2Moderate
123.2Moderate
133.1Moderate
143.1Moderate
153.1Moderate
163.0Moderate
173.0Moderate
183.0Moderate
192.9Moderate
202.9Moderate
212.8Moderate
222.8Moderate
232.7Moderate
242.7Moderate
252.6Moderate
262.6Moderate
272.5Moderate
282.5Moderate
292.4Moderate
302.4Moderate
Planning a trip in September

Is September a good time to visit Sint-Niklaas?

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

5.9
Sightseeing
4th-best month of the year
2.5
Beach & pool
4th-best month of the year

September is a reasonable time to visit Sint-Niklaas for sightseeing.

What to pack for Sint-Niklaas in September

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

In September, Sint-Niklaas sees daytime highs around 19°C and nights near 12°C. Worth packing: rain gear. About 10 days see rain.

rain gear

Sea temperature near Sint-Niklaas in September

The nearest coast averages about 18°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 58 km away) is warmest in August at about 19°C and coldest in February near 6°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
Jan6Bracing
Feb6Bracing
Mar6Bracing
Apr9Bracing
May12Bracing
Jun16Cool
Jul18Cool
Aug19Cool
Sep18Cool
Oct15Bracing
Nov11Bracing
Dec8Bracing

UV index in Sint-Niklaas 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 Sint-Niklaas peaks around June 23 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.

025710JanFebMarAprMayJunJulAugSepOctNovDecLowModerateHighModerateLowJun 23UV 6Jan 1UV 1
UV index (midday)Level
Jan1Low
Feb1Low
Mar3Moderate
Apr4Moderate
May6High
Jun6High
Jul6High
Aug6High
Sep4Moderate
Oct2Moderate
Nov1Low
Dec1Low

Air quality in Sint-Niklaas 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 Sint-Niklaas is worst in April — around 18 µg/m³ PM2.5 (moderate), and holds fairly steady the rest of the year.

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

01020JanFebMarAprMayJunJulAugSepOctNovDecModerateGoodApr 1317 µg/m³Dec 1511 µg/m³
PM2.5 (µg/m³)Level
Jan13Moderate
Feb13Moderate
Mar17Moderate
Apr18Moderate
May16Moderate
Jun15Moderate
Jul14Moderate
Aug15Moderate
Sep15Moderate
Oct13Moderate
Nov12Moderate
Dec11Good
Location & terrain

Where is Sint-Niklaas?

Sint-Niklaas sits at 51.2°N, 4.1°E, 21 m above sea level, in Belgium. The nearest listed city is Sint-Gillis-Waas, 6.0 km away.

Topography around Sint-Niklaas

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

Within 3 km, the terrain around Sint-Niklaas has only modest variations in elevation — a maximum elevation change of 36 m around an average of 18 m above sea level; within 16 km, only modest variations in elevation — a maximum elevation change of 71 m; within 80 km, significant variations in elevation — a maximum elevation change of 323 m.

The land around Sint-Niklaas is covered by artificial surfaces (37%), grassland (26%) and trees (20%) within 3 km, grassland (30%), cropland (25%) and trees (23%) within 16 km, and cropland (33%), grassland (23%) and trees (20%) within 80 km.

3 km
36 m
16 km
71 m
80 km
323 m
treesgrasslandcroplandartificial surfaceswater
September weather nearby: Sint-Gillis-Waas 6.0 km · Temse 6.0 km · Hamme 7.0 km · Stekene 9.0 km · Beveren 9.0 km · Bornem 10 km · Lokeren 13 km · Zele 13 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 Sint-Niklaas (51.1651°, 4.1437°, elevation 21 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).