Boulogne-sur-Mer weather in August

In August, Boulogne-sur-Mer sees average daytime highs of 20°C and overnight lows near 15°C, with 70 mm of rain across 10.4 wet days and about 14.3 hours of daylight. It is the 1st-warmest and 5th-wettest month of the year here.

Day-to-day highs hold fairly steady near 20°C through the month. The sky is clear or mostly clear about 25% 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 Boulogne-sur-Mer's 2nd-clearest and 12th-windiest month. For the whole year in context, see Boulogne-sur-Mer's year-round climate.

Daytime high
20°
1st warmest
Overnight low
15°
12th coldest
Rainfall
70 mm
10.4 wet days
Daylight
14 h 18 min
5:47 AM – 8:08 PM
Cloud cover
59%
2nd clearest
Wind
18 km/h
12th windiest
Solar energy
4.8 kWh/m²
Travel score
6.2
out of 10
Air quality
Moderate
PM2.5 11.8 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

Day-to-day highs hold fairly steady near 20°C through the month.

A typical August day in Boulogne-sur-Mer reaches about 20°C in the afternoon and slips back to 15°C overnight — a 5°C spread between the day's warmth and the night's chill. On most days the high lands between 17°C and 23°C. Set against its neighbours, August runs on par with July and about 2°C warmer than September.

10°15°20°25°151015202531
Avg high (°C)Avg low (°C)
12016
22016
32016
42016
52016
62016
72016
82016
92016
102016
112016
122016
132016
142015
152015
162015
172015
182015
192015
202015
212015
222015
232015
241915
251915
261915
271915
281915
291915
301915
311915

How August really feels in Boulogne-sur-Mer

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.

Boulogne-sur-Mer weather by month

How August compares with the rest of the year at a glance. August is the 1st-warmest and 5th-wettest month here — the current month is highlighted below.

MonthHigh / Low (°C)Rainfall (mm)Wet daysSnow daysDaylight (hours)Travel score
Jan / 8814.30.98.20.9
Feb / 6411.60.99.71.0
Mar / 5310.80.511.51.9
Apr12° / 4810.1013.53.0
May14° / 10°5710.7015.24.2
Jun17° / 13°529.5016.25.5
Jul19° / 15°5510.2015.86.2
Aug20° / 15°7010.4014.36.2
Sep18° / 13°6911.2012.45.5
Oct15° / 11°10114.3010.43.9
Nov11° / 10715.90.18.72.2
Dec / 10614.70.77.81.3

Cloud cover in August

ClearMostly clearPartly cloudyMostly cloudyOvercast

The sky is clear or mostly clear about 25% of the time in August.

Beyond those clear spells, partly cloudy skies cover about 23% of August, with mostly cloudy or overcast conditions the remaining 52%. Skies tend to cloud over as the month goes on.

0%25%50%75%100%151015202531
Clearer (%)Cloudier (%)
15446
25446
35446
45347
55248
65248
75149
85050
95050
104951
114951
124951
134852
144852
154852
164852
174753
184654
194654
204654
214654
224654
234654
244654
254654
264654
274654
284555
294654
304654
314555

Chance of precipitation in August

Any precipitation

Boulogne-sur-Mer gets around 70 mm of rain over 10.4 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
2733
2832
2932
3032
3131

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 52% of days. It rarely turns muggy — the humid and sticky bands barely register.

0%25%50%75%100%151015202531
Dry (%)Comfortable (%)Humid (%)Muggy (%)
11961200
21960201
31960201
41960201
51960201
62059201
72059201
82157202
92157202
102255212
112354212
122354212
132453212
142552212
152552212
162651212
172651212
182751211
192851201
202950201
213050201
223149191
233348181
243547181
253646171
263845170
274044160
284143150
294342150
304441140
314640140

Wind in August

Winds average 18 km/h in August, the calmest month.

Across August, daily wind ranges from about 17 km/h on the calmest days to 19 km/h at its breeziest. It stays fairly steady from day to day.

0510152025151015202531
Wind speed (km/h)Feels
117light breeze
217light breeze
317light breeze
417light breeze
517light breeze
617light breeze
717light breeze
817light breeze
917light breeze
1017light breeze
1117light breeze
1217light breeze
1317light breeze
1417light breeze
1518light breeze
1618light breeze
1718light breeze
1818light breeze
1918light breeze
2018light breeze
2118light breeze
2218light breeze
2318light breeze
2418light breeze
2518light breeze
2618light breeze
2718light breeze
2818light breeze
2918light breeze
3019light breeze
3119light 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 5:25 AM to 6:11 AM, and sunset from 8:35 PM to 7:36 PM.

12 AM4 AM8 AM12 PM4 PM8 PM12 AM151015202531
Daylight (h)Sunrise (AM)Sunset (PM)
115.25:258:35
215.15:268:33
315.15:288:31
415.05:298:30
515.05:318:28
614.95:328:26
714.95:348:25
814.85:358:23
914.75:378:21
1014.75:388:19
1114.65:408:17
1214.65:418:16
1314.55:438:14
1414.55:448:12
1514.45:468:10
1614.35:478:08
1714.35:498:06
1814.25:518:04
1914.25:528:02
2014.15:548:00
2114.05:557:58
2214.05:577:56
2313.95:587:54
2413.96:007:51
2513.86:027:49
2613.76:037:47
2713.76:057:45
2813.66:067:43
2913.56:087:41
3013.56:107:38
3113.46:117:36

Solar energy in August

Daily solar energy (kWh/m²)

Average shortwave solar energy reaching the ground each day in August, about 4.8 kWh/m².

For context, solar energy here swings from a low near 0.71 kWh/m² to a high of 5.83 kWh/m² in June across the year — August's 4.8 kWh/m² falls in the middle.

0246151015202531
Solar energy (kWh/m²)Level
15.4Bright
25.4Bright
35.4Bright
45.3Bright
55.3Bright
65.3Bright
75.2Bright
85.2Bright
95.1Bright
105.1Bright
115.0Bright
125.0Bright
135.0Bright
144.9Bright
154.8Bright
164.8Bright
174.8Bright
184.7Bright
194.7Bright
204.6Bright
214.5Bright
224.5Bright
234.5Bright
244.4Bright
254.4Bright
264.3Bright
274.3Bright
284.2Bright
294.2Bright
304.1Bright
314.1Bright
Planning a trip in August

Is August a good time to visit Boulogne-sur-Mer?

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

6.2
Sightseeing
1st-best month of the year
3.1
Beach & pool
1st-best month of the year

August is a reasonable time to visit Boulogne-sur-Mer for sightseeing.

What to pack for Boulogne-sur-Mer in August

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

In August, Boulogne-sur-Mer sees daytime highs around 20°C and nights near 15°C. Worth packing: rain gear and sun protection. About 10 days see rain.

rain gearsun protection

Sea temperature near Boulogne-sur-Mer 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 offshore is warmest in August at about 18°C and coldest in February near 8°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
Jan9Bracing
Feb8Bracing
Mar8Bracing
Apr9Bracing
May11Bracing
Jun14Bracing
Jul16Cool
Aug18Cool
Sep18Cool
Oct16Cool
Nov13Bracing
Dec11Bracing

UV index in Boulogne-sur-Mer 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 Boulogne-sur-Mer peaks around June 20 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 20UV 6Jan 1UV 1
UV index (midday)Level
Jan1Low
Feb1Low
Mar3Moderate
Apr4Moderate
May6High
Jun7High
Jul6High
Aug6High
Sep4Moderate
Oct2Moderate
Nov1Low
Dec1Low
Location & terrain

Where is Boulogne-sur-Mer?

Boulogne-sur-Mer sits at 50.7°N, 1.6°E, 43 m above sea level, in France. The nearest listed city is Outreau, 3.0 km away.

Topography around Boulogne-sur-Mer

How much the land rises and falls, and what covers it, within 3, 16 and 80 km of Boulogne-sur-Mer.

Within 3 km, the terrain around Boulogne-sur-Mer has only modest variations in elevation — a maximum elevation change of 187 m around an average of 54 m above sea level; within 16 km, significant variations in elevation — a maximum elevation change of 274 m; within 80 km, significant variations in elevation — a maximum elevation change of 290 m.

The land around Boulogne-sur-Mer is covered by artificial surfaces (34%), trees (23%) and grassland (22%) within 3 km, water (42%) within 16 km, and water (45%) and cropland (31%) within 80 km.

3 km
187 m
16 km
274 m
80 km
290 m
treesgrasslandcroplandartificial surfacesbare terrainwater
August weather nearby: Outreau 3.0 km · Calais 30 km · Berck-Plage 36 km · Berck 36 km · Saint-Omer 46 km · Dover 49 km · Folkestone 51 km · Deal 57 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 Boulogne-sur-Mer (50.7249°, 1.6137°, elevation 43 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).