Słupsk weather in September

In September, Słupsk sees average daytime highs of 17°C and overnight lows near 12°C, with 78 mm of rain across 12.3 wet days and about 12.5 hours of daylight. It is the 4th-warmest and 4th-wettest month of the year here.

Highs ease over the month, from about 19°C in the first days to 15°C by the end. The sky is clear or mostly clear about 21% of the time in September, and the air most often feels dry.

Daylight stretches from about 13 h 36 min at the start of September to 11 h 24 min by month's end. Set against the rest of the year, September is Słupsk's 6th-clearest and 7th-windiest month. For the whole year in context, see Słupsk's year-round climate.

Daytime high
17°
4th warmest
Overnight low
12°
9th coldest
Rainfall
78 mm
12.3 wet days
Daylight
12 h 24 min
5:33 AM – 5:59 PM
Cloud cover
63%
6th clearest
Wind
18 km/h
7th windiest
Solar energy
2.88 kWh/m²
Travel score
5.0
out of 10

Słupsk is city in the Pomeranian Voivodeship, in the northern part of Poland.

Density
1,870/km²
people per km²
Founded
1000

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 15°C by the end.

A typical September day in Słupsk reaches about 17°C in the afternoon and slips back to 12°C overnight — a 5°C spread between the day's warmth and the night's chill. On most days the high lands between 13°C and 21°C. Set against its neighbours, September runs about 4°C cooler than August and about 5°C warmer than October.

10°15°20°25°151015202530
Avg high (°C)Avg low (°C)
11913
21913
31913
41813
51813
61813
71813
81813
91812
101812
111812
121712
131712
141712
151712
161712
171711
181711
191611
201611
211611
221611
231611
241611
251610
261510
271510
281510
291510
301510

How September really feels in Słupsk

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.

Słupsk weather by month

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

MonthHigh / Low (°C)Rainfall (mm)Wet daysSnow daysDaylight (hours)Travel score
Jan / -1°5912.24.77.60.0
Feb / -1°4710.95.19.30.0
Mar / 5110.53.611.50.3
Apr10° / 368.80.813.72.3
May14° / 5610.5015.74.3
Jun18° / 12°6811.5016.95.6
Jul20° / 15°9113.4016.46.0
Aug21° / 15°8513.7014.75.9
Sep17° / 12°7812.3012.55.0
Oct12° / 8013.60.110.22.8
Nov / 6513.21.48.20.7
Dec / 6613.54.57.10.0

Cloud cover in September

ClearMostly clearPartly cloudyMostly cloudyOvercast

The sky is clear or mostly clear about 21% of the time in September.

Beyond those clear spells, partly cloudy skies cover about 20% of September, with mostly cloudy or overcast conditions the remaining 59%.

0%25%50%75%100%151015202530
Clearer (%)Cloudier (%)
14753
24753
34654
44555
54555
64555
74555
84456
94357
104357
114357
124258
134159
144159
154159
164060
174060
184060
194060
203961
213961
223961
233961
243961
253961
263862
273862
283862
293862
303664

Chance of precipitation in September

Any precipitation

Słupsk gets around 78 mm of rain over 12.3 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 42% and peaks near 50% on the wettest days. The odds ease toward the end of the month.

0%20%40%60%151015202530
Rain chance (%)
150
250
349
449
549
648
747
847
946
1045
1144
1243
1342
1441
1540
1639
1738
1837
1937
2036
2136
2236
2336
2436
2536
2637
2737
2838
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 77% of days. It rarely turns muggy — the humid and sticky bands barely register.

0%25%50%75%100%151015202530
Dry (%)Comfortable (%)Humid (%)
154379
256359
358348
459338
561318
663307
764297
867276
968266
1070255
1171245
1273234
1375214
1477203
1578193
1680182
1781172
1883161
1984151
2085141
2187130
2287130
2388120
2489110
2589110
2690100
2790100
2890100
299190
309190

Wind in September

Winds average 18 km/h in September.

Across September, 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.

0510152025151015202530
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
1318light breeze
1418light 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

Sunrise & sunset in September

DaylightNight

Daylight runs from about 13 h 36 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 132 minutes over September. Sunrise moves from 5:05 AM to 6:00 AM, and sunset from 6:38 PM to 5:23 PM.

12 AM4 AM8 AM12 PM4 PM8 PM12 AM151015202530
Daylight (h)Sunrise (AM)Sunset (PM)
113.65:056:38
213.55:076:36
313.45:096:33
413.35:116:30
513.35:136:28
613.25:146:25
713.15:166:23
813.05:186:20
913.05:206:18
1012.95:226:15
1112.85:246:12
1212.75:266:10
1312.75:286:07
1412.65:296:04
1512.55:316:02
1612.45:335:59
1712.45:355:57
1812.35:375:54
1912.25:395:51
2012.15:415:49
2112.15:435:46
2212.05:455:43
2311.95:465:41
2411.85:485:38
2511.85:505:36
2611.75:525:33
2711.65:545:30
2811.55:565:28
2911.55:585:25
3011.46:005:23

Solar energy in September

Daily solar energy (kWh/m²)

Average shortwave solar energy reaching the ground each day in September, about 2.88 kWh/m².

For context, solar energy here swings from a low near 0.41 kWh/m² to a high of 5.63 kWh/m² in June across the year — September's 2.88 kWh/m² falls in the middle.

01234151015202530
Solar energy (kWh/m²)Level
13.6Moderate
23.5Moderate
33.5Moderate
43.4Moderate
53.4Moderate
63.3Moderate
73.3Moderate
83.2Moderate
93.2Moderate
103.1Moderate
113.1Moderate
123.0Moderate
133.0Moderate
142.9Moderate
152.9Moderate
162.9Moderate
172.8Moderate
182.8Moderate
192.7Moderate
202.7Moderate
212.6Moderate
222.6Moderate
232.6Moderate
242.5Moderate
252.5Moderate
262.4Moderate
272.4Moderate
282.3Moderate
292.3Moderate
302.2Moderate
Planning a trip in September

Is September a good time to visit Słupsk?

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

5.0
Sightseeing
4th-best month of the year
1.2
Beach & pool
4th-best month of the year

September is a reasonable time to visit Słupsk for sightseeing.

What to pack for Słupsk in September

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

In September, Słupsk sees daytime highs around 17°C and nights near 12°C. Worth packing: a warm layer and rain gear. About 12 days see rain.

a warm layerrain gear

Sea temperature near Słupsk in September

The nearest coast averages about 16°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 20 km away) is warmest in August at about 19°C and coldest in February near 3°C.

The water stays below 20°C all year — cool enough that most swimmers want a wetsuit.

0°10°20°JanFebMarAprMayJunJulAugSepOctNovDecbracingcoolrefreshing
Sea temperature (°C)Comfort
Jan4Bracing
Feb3Bracing
Mar3Bracing
Apr5Bracing
May9Bracing
Jun14Bracing
Jul17Cool
Aug19Cool
Sep16Cool
Oct13Bracing
Nov9Bracing
Dec6Bracing

UV index in Słupsk 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 Słupsk peaks around June 18 at about 6 (high) — sunscreen and a hat are worth it in the middle of the day. It bottoms out near December 20 at about 0 (low).

The index reaches 3 or more — the level where the WHO recommends sun protection — in 6 months of the year.

025710JanFebMarAprMayJunJulAugSepOctNovDecLowModerateHighModerateLowJun 18UV 6Dec 20UV 0
UV index (midday)Level
Jan1Low
Feb1Low
Mar3Moderate
Apr4Moderate
May5Moderate
Jun6High
Jul6High
Aug5Moderate
Sep4Moderate
Oct2Low
Nov1Low
Dec0Low
Location & terrain

Where is Słupsk?

Słupsk sits at 54.5°N, 17.0°E, 18 m above sea level, in Poland. The nearest listed city is Ustka, 17 km away.

BytówLęborkKoszalinKościerzynaKartuzyWejherowoBiałogard

Topography around Słupsk

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

Within 3 km, the terrain around Słupsk has only modest variations in elevation — a maximum elevation change of 78 m around an average of 42 m above sea level; within 16 km, only modest variations in elevation — a maximum elevation change of 162 m; within 80 km, significant variations in elevation — a maximum elevation change of 339 m.

The land around Słupsk is covered by trees (45%) and artificial surfaces (33%) within 3 km, trees (40%) and cropland (39%) within 16 km, and trees (39%) and water (30%) within 80 km.

3 km
78 m
16 km
162 m
80 km
339 m
treesgrasslandcroplandartificial surfaceswater
September weather nearby: Ustka 17 km · Bytów 44 km · Lębork 47 km · Koszalin 63 km · Kościerzyna 73 km · Kartuzy 77 km · Wejherowo 79 km · Białogard 85 km

Poland travel facts

Travel advisory
Level 1
Exercise Normal Precautions
Power plugs
Type C / E
230 V · 50 Hz
Prices
≈ 52% of US
price level, 2025
GDP per capita
$28,420
2025
Happiness
6.8 / 10
World Happiness, 2025
Safe drinking water
89%
of population, 2024
Homicide rate
0.8
per 100k, 2023
Road deaths
9.4
per 100k/yr, 2019
Income group
High
World Bank
English
Very high
EF EPI 600
Religion
Roman Catholic 71%refused to answer 21%no religion 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 Słupsk (54.4641°, 17.0287°, elevation 18 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).