Saint-Omer weather in September

In September, Saint-Omer sees average daytime highs of 19°C and overnight lows near 12°C, with 57 mm of rain across 10.1 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 17% 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 30 min by month's end. Set against the rest of the year, September is Saint-Omer's 4th-clearest and 9th-windiest month. For the whole year in context, see Saint-Omer's year-round climate.

Daytime high
19°
4th warmest
Overnight low
12°
9th coldest
Rainfall
57 mm
10.1 wet days
Daylight
12 h 24 min
6:34 AM – 6:57 PM
Cloud cover
66%
4th clearest
Wind
13 km/h
9th windiest
Solar energy
3.23 kWh/m²
Travel score
5.8
out of 10
Air quality
Good
PM10 19.4 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 20°C in the first days to 17°C by the end.

A typical September day in Saint-Omer 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°151015202530
Avg high (°C)Avg low (°C)
12013
22013
32013
42013
52012
62012
72012
82012
91912
101912
111912
121912
131912
141912
151912
161912
171911
181911
191811
201811
211811
221811
231811
241811
251811
261811
271711
281711
291711
301710

How September really feels in Saint-Omer

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.

Saint-Omer 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 / 621218.20.7
Feb / 5310.61.19.71.0
Mar10° / 5110.90.811.52.3
Apr14° / 5211.10.113.53.7
May17° / 6511.3015.25.1
Jun19° / 12°6310.3016.26.0
Jul22° / 14°5911015.86.4
Aug22° / 14°7111.2014.36.4
Sep19° / 12°5710.1012.45.8
Oct15° / 6512010.44.1
Nov10° / 6812.70.38.72.1
Dec / 7512.61.17.80.9

Cloud cover in September

ClearMostly clearPartly cloudyMostly cloudyOvercast

The sky is clear or mostly clear about 17% 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 65%.

0%25%50%75%100%151015202530
Clearer (%)Cloudier (%)
13664
23664
33664
43664
53664
63664
73664
83664
93664
103664
113565
123565
133565
143664
153664
163763
173763
183664
193664
203664
213664
223565
233565
243565
253565
263565
273367
283268
293268
303169

Chance of precipitation in September

Any precipitation

Saint-Omer gets around 57 mm of rain over 10.1 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 34% and peaks near 39% on the wettest days. The odds climb toward the end of the month.

0%10%20%30%40%50%151015202530
Rain chance (%)
130
230
330
430
530
631
731
832
933
1033
1134
1234
1334
1434
1534
1635
1735
1835
1936
2036
2136
2236
2336
2437
2537
2638
2738
2839
2939
3039

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 68% of days. It rarely turns muggy — the humid and sticky bands barely register.

0%25%50%75%100%151015202530
Dry (%)Comfortable (%)Humid (%)
1553510
256359
357349
458339
559329
660319
761309
861309
963298
1064288
1165278
1266277
1367267
1469256
1570246
1671245
1772235
1873234
1973234
2074233
2174233
2275232
2374242
2474242
2575241
2675241
2775241
2876231
2976231
3076231

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 24 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 114 minutes over September. Sunrise moves from 6:10 AM to 6:57 AM, and sunset from 7:31 PM to 6:24 PM.

12 AM4 AM8 AM12 PM4 PM8 PM12 AM151015202530
Daylight (h)Sunrise (AM)Sunset (PM)
113.46:107:31
213.36:127:29
313.26:137:27
413.26:157:24
513.16:167:22
613.06:187:20
713.06:207:18
812.96:217:15
912.86:237:13
1012.86:247:11
1112.76:267:08
1212.66:287:06
1312.66:297:04
1412.56:317:01
1512.46:326:59
1612.46:346:57
1712.36:366:54
1812.26:376:52
1912.26:396:50
2012.16:406:47
2112.06:426:45
2212.06:446:43
2311.96:456:40
2411.96:476:38
2511.86:486:36
2611.76:506:33
2711.76:526:31
2811.66:536:29
2911.56:556:26
3011.56:576:24

Solar energy in September

Daily solar energy (kWh/m²)

Average shortwave solar energy reaching the ground each day in September, about 3.23 kWh/m².

For context, solar energy here swings from a low near 0.68 kWh/m² to a high of 5.56 kWh/m² in June across the year — September's 3.23 kWh/m² falls in the middle.

01234151015202530
Solar energy (kWh/m²)Level
13.8Moderate
23.8Moderate
33.8Moderate
43.7Moderate
53.7Moderate
63.6Moderate
73.6Moderate
83.5Moderate
93.5Moderate
103.5Moderate
113.4Moderate
123.4Moderate
133.3Moderate
143.3Moderate
153.3Moderate
163.2Moderate
173.2Moderate
183.1Moderate
193.1Moderate
203.0Moderate
213.0Moderate
222.9Moderate
232.9Moderate
242.8Moderate
252.8Moderate
262.7Moderate
272.7Moderate
282.6Moderate
292.6Moderate
302.5Moderate
Planning a trip in September

Is September a good time to visit Saint-Omer?

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

5.8
Sightseeing
4th-best month of the year
2.4
Beach & pool
4th-best month of the year

September is a reasonable time to visit Saint-Omer for sightseeing.

What to pack for Saint-Omer in September

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

In September, Saint-Omer 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 Saint-Omer 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 43 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
Mar7Bracing
Apr9Bracing
May12Bracing
Jun15Bracing
Jul17Cool
Aug18Cool
Sep18Cool
Oct15Cool
Nov13Bracing
Dec10Bracing

UV index in Saint-Omer 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 Saint-Omer peaks around June 22 at about 6 (high) — sunscreen and a hat are worth it in the middle of the day. 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 6 months of the year.

025710JanFebMarAprMayJunJulAugSepOctNovDecLowModerateHighModerateLowJun 22UV 6Dec 21UV 1
UV index (midday)Level
Jan1Low
Feb1Low
Mar3Moderate
Apr4Moderate
May6High
Jun7High
Jul6High
Aug7High
Sep4Moderate
Oct2Moderate
Nov1Low
Dec1Low
Location & terrain

Where is Saint-Omer?

Saint-Omer sits at 50.7°N, 2.3°E, 10 m above sea level, in France. The nearest listed city is Hazebrouck, 20 km away.

Topography around Saint-Omer

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

Within 3 km, the terrain around Saint-Omer has only modest variations in elevation — a maximum elevation change of 85 m around an average of 18 m above sea level; within 16 km, only modest variations in elevation — a maximum elevation change of 206 m; within 80 km, significant variations in elevation — a maximum elevation change of 272 m.

The land around Saint-Omer is covered by trees (25%), artificial surfaces (25%) and grassland (24%) within 3 km, cropland (57%) within 16 km, and cropland (41%) and water (31%) within 80 km.

3 km
85 m
16 km
206 m
80 km
272 m
treesgrasslandcroplandartificial surfaceswaterwetland
September weather nearby: Hazebrouck 20 km · Grande-Synthe 30 km · Coudekerque-Branche 32 km · Saint-Pol-sur-Mer 32 km · Dunkirk 33 km · Poperinge 35 km · Bruay-la-Buissière 36 km · Béthune 36 km

France travel facts

Travel advisory
Level 2
Exercise Increased Caution
Power plugs
Type C / E
230 V · 50 Hz
Prices
≈ 77% of US
price level, 2025
GDP per capita
$48,986
2025
Happiness
6.6 / 10
World Happiness, 2025
Safe drinking water
100%
of population, 2024
Homicide rate
1.3
per 100k, 2023
Road deaths
5.1
per 100k/yr, 2019
Income group
High
World Bank
English
Moderate
EF EPI 539
Religion
Roman Catholic 47%none 33%Muslim 4%Protestant 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 Saint-Omer (50.7483°, 2.2609°, elevation 10 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).