Grande-Synthe weather in August

In August, Grande-Synthe sees average daytime highs of 22°C and overnight lows near 15°C, with 63 mm of rain across 10.5 wet days and about 14.3 hours of daylight. It is the 1st-warmest and 4th-wettest month of the year here.

Highs ease over the month, from about 23°C in the first days to 21°C by the end. The sky is clear or mostly clear about 22% of the time in August, and the air most often feels comfortable.

Daylight stretches from about 15 h 12 min at the start of August to 13 h 24 min by month's end. Set against the rest of the year, August is Grande-Synthe's 2nd-clearest and 12th-windiest month. For the whole year in context, see Grande-Synthe's year-round climate.

Daytime high
22°
1st warmest
Overnight low
15°
12th coldest
Rainfall
63 mm
10.5 wet days
Daylight
14 h 24 min
5:44 AM – 8:06 PM
Cloud cover
61%
2nd clearest
Wind
14 km/h
12th windiest
Solar energy
4.64 kWh/m²
Travel score
6.5
out of 10
Air quality
Good
PM10 23.4 µg/m³ · 2019

Air quality: WHO Ambient Air Quality Database. Density & description: Wikidata (CC0), GeoNames.

Temperature in August

Average highAverage lowShaded bands: 10–90% of days

Highs ease over the month, from about 23°C in the first days to 21°C by the end.

A typical August day in Grande-Synthe reaches about 22°C in the afternoon and slips back to 15°C overnight — a 7°C spread between the day's warmth and the night's chill. On most days the high lands between 18°C and 26°C. Set against its neighbours, August runs on par with July and about 3°C warmer than September.

10°15°20°25°30°151015202531
Avg high (°C)Avg low (°C)
12315
22315
32315
42315
52315
62215
72215
82215
92215
102215
112215
122215
132215
142215
152215
162215
172215
182215
192215
202215
212115
222115
232115
242114
252114
262114
272114
282114
292114
302014
312014

How August really feels in Grande-Synthe

Once humidity and wind are folded in, August 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

August sits comfortably in between — no days that feel dangerously hot or drop to a hard freeze once humidity and wind are folded in.

Grande-Synthe weather by month

How August compares with the rest of the year at a glance. August is the 1st-warmest and 4th-wettest month here — the current month is highlighted below.

MonthHigh / Low (°C)Rainfall (mm)Wet daysSnow daysDaylight (hours)Travel score
Jan / 5611.80.98.20.9
Feb / 47100.89.61.1
Mar10° / 4610.60.511.52.3
Apr13° / 4410.20.113.53.7
May16° / 10°5410.7015.35.1
Jun19° / 12°549.9016.26.0
Jul22° / 15°5410.5015.86.5
Aug22° / 15°6310.5014.36.5
Sep19° / 13°559.8012.45.9
Oct15° / 10°6511.9010.44.2
Nov11° / 6512.80.38.72.3
Dec / 6812.50.87.81.1

Cloud cover in August

ClearMostly clearPartly cloudyMostly cloudyOvercast

The sky is clear or mostly clear about 22% of the time in August.

Beyond those clear spells, partly cloudy skies cover about 21% of August, with mostly cloudy or overcast conditions the remaining 57%. Skies tend to cloud over as the month goes on.

0%25%50%75%100%151015202531
Clearer (%)Cloudier (%)
14852
24852
34852
44852
54753
64753
74753
84654
94555
104555
114555
124456
134456
144357
154258
164258
174258
184357
194357
204357
214159
224159
234159
244159
254159
264060
274060
284060
293862
303961
313862

Chance of precipitation in August

Any precipitation

Grande-Synthe gets around 63 mm of rain over 10.5 wet days in August. 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 36% on the wettest days.

0%10%20%30%40%50%151015202531
Rain chance (%)
132
232
332
432
533
633
733
833
934
1034
1134
1235
1335
1436
1536
1636
1736
1836
1936
2036
2136
2235
2335
2434
2533
2633
2732
2831
2931
3030
3129

Humidity in August

DryComfortableHumidMuggyOppressiveMiserable

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

By dew point, August lands in the comfortable band about 48% of days. It rarely turns muggy — the humid and sticky bands barely register.

0%25%50%75%100%151015202531
Dry (%)Comfortable (%)Humid (%)Muggy (%)
12455192
22455192
32554192
42554192
52553193
62652193
72652193
82751193
92751193
102751193
112850193
122850193
132949193
142949193
153049193
163048193
173048192
183148192
193248182
203347182
213447182
223546172
233745171
243844161
254043161
264242151
274441151
284540141
294739141
304838141
314937131

Wind in August

Winds average 14 km/h in August, the calmest month.

Across August, daily wind ranges from about 14 km/h on the calmest days to 15 km/h at its breeziest. It stays fairly steady from day to day.

05101520151015202531
Wind speed (km/h)Feels
114light breeze
214light breeze
314light breeze
414light breeze
514light breeze
614light breeze
714light breeze
814light breeze
914light breeze
1014light breeze
1114light breeze
1214light breeze
1314light breeze
1414light breeze
1514light breeze
1614light breeze
1715light breeze
1815light breeze
1915light breeze
2015light breeze
2115light breeze
2215light breeze
2315light breeze
2415light breeze
2515light breeze
2615light breeze
2715light breeze
2815light breeze
2915light breeze
3015light breeze
3115light breeze

Sunrise & sunset in August

DaylightNight

Daylight runs from about 15 h 12 min at the start of August to 13 h 24 min by month's end. The lit band spans sunrise to sunset each day.

Days shrink by about 108 minutes over August. Sunrise moves from 5:21 AM to 6:08 AM, and sunset from 8:33 PM to 7:34 PM.

12 AM4 AM8 AM12 PM4 PM8 PM12 AM151015202531
Daylight (h)Sunrise (AM)Sunset (PM)
115.25:218:33
215.25:228:31
315.15:248:30
415.05:258:28
515.05:278:26
614.95:288:25
714.95:308:23
814.85:318:21
914.85:338:19
1014.75:348:17
1114.75:368:16
1214.65:388:14
1314.55:398:12
1414.55:418:10
1514.45:428:08
1614.45:448:06
1714.35:458:04
1814.25:478:02
1914.25:498:00
2014.15:507:58
2114.15:527:56
2214.05:537:54
2313.95:557:51
2413.95:577:49
2513.85:587:47
2613.86:007:45
2713.76:017:43
2813.66:037:40
2913.66:057:38
3013.56:067:36
3113.46:087:34

Solar energy in August

Daily solar energy (kWh/m²)

Average shortwave solar energy reaching the ground each day in August, about 4.64 kWh/m².

For context, solar energy here swings from a low near 0.66 kWh/m² to a high of 5.63 kWh/m² in June across the year — August's 4.64 kWh/m² falls in the middle.

0246151015202531
Solar energy (kWh/m²)Level
15.3Bright
25.3Bright
35.2Bright
45.2Bright
55.1Bright
65.1Bright
75.1Bright
85.0Bright
95.0Bright
104.9Bright
114.9Bright
124.8Bright
134.8Bright
144.7Bright
154.7Bright
164.7Bright
174.6Bright
184.5Bright
194.5Bright
204.5Bright
214.4Bright
224.3Bright
234.3Bright
244.3Bright
254.2Bright
264.2Bright
274.1Bright
284.1Bright
294.0Bright
304.0Moderate
313.9Moderate
Planning a trip in August

Is August a good time to visit Grande-Synthe?

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

6.5
Sightseeing
1st-best month of the year
4.3
Beach & pool
1st-best month of the year

August is a reasonable time to visit Grande-Synthe for sightseeing.

What to pack for Grande-Synthe in August

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

In August, Grande-Synthe sees daytime highs around 22°C and nights near 15°C. Worth packing: rain gear and sun protection. About 11 days see rain.

rain gearsun protection

Sea temperature near Grande-Synthe in August

The nearest coast averages about 18°C in August — the other half of the beach question. The full-year curve and swim-comfort zones are below.

The sea at the nearest coast (about 13 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 Grande-Synthe in August

LowModerateHighVery highExtreme

Clear-sky midday UV in August 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 Grande-Synthe 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 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 22UV 6Jan 1UV 1
UV index (midday)Level
Jan1Low
Feb1Low
Mar3Moderate
Apr4Moderate
May6High
Jun6High
Jul6High
Aug6High
Sep4Moderate
Oct2Moderate
Nov1Low
Dec1Low
Location & terrain

Where is Grande-Synthe?

Grande-Synthe sits at 51.0°N, 2.3°E, 2 m above sea level, in France. The nearest listed city is Saint-Pol-sur-Mer, 3.0 km away.

Topography around Grande-Synthe

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

Within 3 km, the terrain around Grande-Synthe has only modest variations in elevation — a maximum elevation change of 42 m around an average of 5 m above sea level; within 16 km, only modest variations in elevation — a maximum elevation change of 52 m; within 80 km, significant variations in elevation — a maximum elevation change of 290 m.

The land around Grande-Synthe is covered by artificial surfaces (50%) and trees (22%) within 3 km, water (39%) and cropland (37%) within 16 km, and water (38%) and cropland (34%) within 80 km.

3 km
42 m
16 km
52 m
80 km
290 m
treesgrasslandcroplandartificial surfacesbare terrainwater
August weather nearby: Saint-Pol-sur-Mer 3.0 km · Dunkirk 6.0 km · Coudekerque-Branche 7.0 km · Koksijde 26 km · Saint-Omer 30 km · Calais 32 km · Poperinge 35 km · Hazebrouck 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 Grande-Synthe (51.0154°, 2.2997°, elevation 2 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).