Olsztyn weather in September

In September, Olsztyn sees average daytime highs of 17°C and overnight lows near 9°C, with 59 mm of rain across 9.8 wet days and about 12.5 hours of daylight. It is the 5th-warmest and 5th-wettest month of the year here.

Highs ease over the month, from about 20°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 30 min at the start of September to 11 h 24 min by month's end. Set against the rest of the year, September is Olsztyn's 6th-clearest and 7th-windiest month. For the whole year in context, see Olsztyn's year-round climate.

Daytime high
17°
5th warmest
Overnight low
9th coldest
Rainfall
59 mm
9.8 wet days
Daylight
12 h 24 min
5:20 AM – 5:45 PM
Cloud cover
66%
6th clearest
Wind
13 km/h
7th windiest
Solar energy
2.86 kWh/m²
Travel score
5.4
out of 10

Olsztyn is city in Warmian-Masurian Voivodeship, Poland.

Air quality
Moderate
PM2.5 15 µg/m³ · 2019
Density
1,929/km²
people per km²
Founded
1353

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 15°C by the end.

A typical September day in Olsztyn reaches about 17°C in the afternoon and slips back to 9°C overnight — a 8°C spread between the day's warmth and the night's chill. On most days the high lands between 13°C and 23°C. Set against its neighbours, September runs about 5°C cooler than August and about 6°C warmer than October.

10°20°30°151015202530
Avg high (°C)Avg low (°C)
12011
22011
32011
41911
51911
61911
71910
81910
91910
101810
111810
121810
131810
14189
15189
16179
17179
18179
19179
20179
21178
22168
23168
24168
25168
26168
27158
28158
29157
30157

How September really feels in Olsztyn

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.

Olsztyn weather by month

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

MonthHigh / Low (°C)Rainfall (mm)Wet daysSnow daysDaylight (hours)Travel score
Jan-0° / -4°4310.86.67.80.0
Feb / -4°378.85.59.40.0
Mar / -1°4310.34.111.50.4
Apr12° / 419.71.313.73.3
May18° / 6412.20.115.65.4
Jun21° / 11°7112.3016.75.9
Jul23° / 13°8613.3016.36.3
Aug22° / 13°6611.5014.66.5
Sep17° / 599.8012.55.4
Oct11° / 5010.10.410.22.8
Nov / 429.92.48.30.4
Dec / -2°4510.45.47.30.0

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 15% of September, with mostly cloudy or overcast conditions the remaining 64%.

0%25%50%75%100%151015202530
Clearer (%)Cloudier (%)
14060
24060
33961
43862
53862
63763
73763
83763
93664
103565
113565
123565
133565
143565
153664
163664
173466
183466
193565
203565
213565
223664
233664
243664
253565
263565
273664
283664
293565
303565

Chance of precipitation in September

Any precipitation

Olsztyn gets around 59 mm of rain over 9.8 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 33% and peaks near 39% on the wettest days. The odds ease toward the end of the month.

0%10%20%30%40%50%151015202530
Rain chance (%)
139
239
339
439
539
639
738
838
937
1037
1136
1235
1334
1433
1532
1631
1730
1829
1929
2028
2128
2228
2328
2428
2528
2629
2729
2830
2930
3031

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 85% of days. It rarely turns muggy — the humid and sticky bands barely register.

0%25%50%75%100%151015202530
Dry (%)Comfortable (%)Humid (%)
170273
271263
371263
472253
574242
675232
776222
878202
979192
1080182
1181172
1282162
1383152
1484142
1586131
1687121
1788111
1889101
199091
209091
219181
229370
239370
249460
259460
269460
279550
289550
299550
309550

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
2114light breeze
2214light breeze
2314light breeze
2414light breeze
2514light breeze
2614light breeze
2714light breeze
2814light breeze
2914light breeze
3014light breeze

Sunrise & sunset in September

DaylightNight

Daylight runs from about 13 h 30 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 126 minutes over September. Sunrise moves from 4:52 AM to 5:46 AM, and sunset from 6:23 PM to 5:09 PM.

12 AM4 AM8 AM12 PM4 PM8 PM12 AM151015202530
Daylight (h)Sunrise (AM)Sunset (PM)
113.54:526:23
213.44:546:21
313.44:566:18
413.34:586:16
513.25:006:13
613.25:016:11
713.15:036:08
813.05:056:06
912.95:076:03
1012.95:096:00
1112.85:115:58
1212.75:125:55
1312.65:145:53
1412.65:165:50
1512.55:185:48
1612.45:205:45
1712.35:225:42
1812.35:235:40
1912.25:255:37
2012.15:275:35
2112.15:295:32
2212.05:315:30
2311.95:335:27
2411.85:345:24
2511.85:365:22
2611.75:385:19
2711.65:405:17
2811.55:425:14
2911.55:445:12
3011.45:465:09

Solar energy in September

Daily solar energy (kWh/m²)

Average shortwave solar energy reaching the ground each day in September, about 2.86 kWh/m².

For context, solar energy here swings from a low near 0.44 kWh/m² to a high of 5.34 kWh/m² in June across the year — September's 2.86 kWh/m² falls in the middle.

01234151015202530
Solar energy (kWh/m²)Level
13.5Moderate
23.5Moderate
33.4Moderate
43.4Moderate
53.3Moderate
63.3Moderate
73.2Moderate
83.2Moderate
93.1Moderate
103.1Moderate
113.0Moderate
123.0Moderate
133.0Moderate
142.9Moderate
152.9Moderate
162.8Moderate
172.8Moderate
182.8Moderate
192.7Moderate
202.7Moderate
212.7Moderate
222.6Moderate
232.6Moderate
242.5Moderate
252.5Moderate
262.5Moderate
272.4Moderate
282.4Moderate
292.3Moderate
302.3Moderate
Planning a trip in September

Is September a good time to visit Olsztyn?

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

5.4
Sightseeing
4th-best month of the year
1.6
Beach & pool
5th-best month of the year

September is a reasonable time to visit Olsztyn for sightseeing.

What to pack for Olsztyn in September

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

In September, Olsztyn sees daytime highs around 17°C and nights near 9°C. Worth packing: rain gear. About 10 days see rain.

rain gear

UV index in Olsztyn 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 Olsztyn peaks around June 23 at about 6 (high) — a little sun protection helps at midday. It bottoms out near December 19 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 23UV 6Dec 19UV 0
UV index (midday)Level
Jan1Low
Feb1Low
Mar3Moderate
Apr4Moderate
May5High
Jun6High
Jul6High
Aug6High
Sep4Moderate
Oct2Low
Nov1Low
Dec0Low

Air quality in Olsztyn 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 Olsztyn is worst in March — around 21 µg/m³ PM2.5 (moderate), about 2.3× the cleanest month (December, 9 µg/m³).

Seasonal pattern from CAMS reanalysis, scaled to Olsztyn's WHO annual average of 15 µg/m³.

0102030JanFebMarAprMayJunJulAugSepOctNovDecModerateGoodMar 2221 µg/m³Dec 159 µg/m³
PM2.5 (µg/m³)Level
Jan12Good
Feb14Moderate
Mar21Moderate
Apr20Moderate
May17Moderate
Jun18Moderate
Jul17Moderate
Aug16Moderate
Sep14Moderate
Oct12Good
Nov11Good
Dec9Good
Location & terrain

Where is Olsztyn?

Olsztyn sits at 53.8°N, 20.5°E, 151 m above sea level, in Poland. The nearest listed city is Ostróda, 36 km away.

Lidzbark WarmińskiSzczytnoMrągowoBartoszyceDziałdowoIławaKętrzyn

Topography around Olsztyn

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

Within 3 km, the terrain around Olsztyn has only modest variations in elevation — a maximum elevation change of 73 m around an average of 130 m above sea level; within 16 km, only modest variations in elevation — a maximum elevation change of 125 m; within 80 km, significant variations in elevation — a maximum elevation change of 324 m.

The land around Olsztyn is covered by trees (54%) and artificial surfaces (38%) within 3 km, trees (51%) and grassland (26%) within 16 km, and trees (42%), cropland (31%) and grassland (24%) within 80 km.

3 km
73 m
16 km
125 m
80 km
324 m
treesgrasslandcroplandartificial surfaceswater
September weather nearby: Ostróda 36 km · Lidzbark Warmiński 38 km · Szczytno 41 km · Mrągowo 54 km · Bartoszyce 56 km · Działdowo 64 km · Iława 64 km · Kętrzyn 66 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 Olsztyn (53.7838°, 20.4927°, elevation 151 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. 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).