Siedlce weather in September

In September, Siedlce sees average daytime highs of 18°C and overnight lows near 9°C, with 57 mm of rain across 9.4 wet days and about 12.4 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 16°C by the end. The sky is clear or mostly clear about 23% 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 24 min by month's end. Set against the rest of the year, September is Siedlce's 6th-clearest and 8th-windiest month. For the whole year in context, see Siedlce's year-round climate.

Daytime high
18°
5th warmest
Overnight low
9th coldest
Rainfall
57 mm
9.4 wet days
Daylight
12 h 24 min
5:13 AM – 5:37 PM
Cloud cover
64%
6th clearest
Wind
12 km/h
8th windiest
Solar energy
2.98 kWh/m²
Travel score
5.7
out of 10

Siedlce is city in eastern Poland.

Air quality
Elevated
PM2.5 19.6 µg/m³ · 2019
Density
2,412/km²
people per km²
Founded
1448

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 16°C by the end.

A typical September day in Siedlce reaches about 18°C in the afternoon and slips back to 9°C overnight — a 9°C spread between the day's warmth and the night's chill. On most days the high lands between 13°C and 24°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)
12111
22111
32011
42011
52011
62010
72010
81910
91910
101910
111910
12199
13199
14189
15189
16189
17189
18189
19178
20178
21178
22178
23178
24168
25168
26167
27167
28167
29157
30157

How September really feels in Siedlce

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.

Siedlce 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 / -4°419.96.580.0
Feb / -4°379.66.59.50.0
Mar / -1°4210.6411.50.6
Apr13° / 469.7113.63.7
May19° / 7012.30.115.45.7
Jun22° / 12°7311.9016.46.1
Jul24° / 14°83130166.5
Aug23° / 13°6410.4014.56.8
Sep18° / 579.4012.45.7
Oct12° / 469.40.310.33.1
Nov / 399.52.88.50.5
Dec / -3°419.95.67.60.0

Cloud cover in September

ClearMostly clearPartly cloudyMostly cloudyOvercast

The sky is clear or mostly clear about 23% of the time in September.

Beyond those clear spells, partly cloudy skies cover about 16% of September, with mostly cloudy or overcast conditions the remaining 61%.

0%25%50%75%100%151015202530
Clearer (%)Cloudier (%)
14258
24357
34159
44159
54159
64060
73961
83961
93961
103961
113961
123961
133961
143961
153961
163961
173961
183961
193961
203961
213961
223961
233862
243862
253862
263763
273763
283763
293664
303664

Chance of precipitation in September

Any precipitation

Siedlce gets around 57 mm of rain over 9.4 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 31% and peaks near 34% on the wettest days.

0%10%20%30%40%151015202530
Rain chance (%)
134
234
334
434
534
634
733
833
933
1032
1132
1232
1331
1431
1530
1630
1730
1829
1929
2029
2129
2229
2329
2430
2530
2630
2730
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 84% of days. It rarely turns muggy — the humid and sticky bands barely register.

0%25%50%75%100%151015202530
Dry (%)Comfortable (%)Humid (%)
170255
272244
372244
473234
575223
675223
776213
877203
978202
1079192
1180182
1281172
1382162
1483152
1583152
1685141
1786131
1887121
1988111
2089101
219091
229181
239181
249370
259370
269460
279460
289460
299550
309550

Wind in September

Winds average 12 km/h in September.

Across September, daily wind ranges from about 12 km/h on the calmest days to 13 km/h at its breeziest. It stays fairly steady from day to day.

051015151015202530
Wind speed (km/h)Feels
112calm
212calm
312calm
412calm
512calm
612light breeze
712light breeze
812light breeze
912light breeze
1012light breeze
1112light breeze
1212light breeze
1312light breeze
1412light breeze
1512light breeze
1612light breeze
1712light breeze
1812light breeze
1912light breeze
2012light breeze
2112light breeze
2212light breeze
2313light breeze
2413light breeze
2513light breeze
2613light breeze
2713light breeze
2813light breeze
2913light breeze
3013light breeze

Sunrise & sunset in September

DaylightNight

Daylight runs from about 13 h 24 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 120 minutes over September. Sunrise moves from 4:48 AM to 5:37 AM, and sunset from 6:13 PM to 5:03 PM.

12 AM4 AM8 AM12 PM4 PM8 PM12 AM151015202530
Daylight (h)Sunrise (AM)Sunset (PM)
113.44:486:13
213.44:496:11
313.34:516:09
413.24:536:06
513.24:556:04
613.14:566:01
713.04:585:59
812.95:005:57
912.95:015:54
1012.85:035:52
1112.75:055:49
1212.75:065:47
1312.65:085:44
1412.55:105:42
1512.55:125:40
1612.45:135:37
1712.35:155:35
1812.35:175:32
1912.25:185:30
2012.15:205:27
2112.15:225:25
2212.05:235:22
2311.95:255:20
2411.85:275:18
2511.85:295:15
2611.75:305:13
2711.65:325:10
2811.65:345:08
2911.55:365:05
3011.45:375:03

Solar energy in September

Daily solar energy (kWh/m²)

Average shortwave solar energy reaching the ground each day in September, about 2.98 kWh/m².

For context, solar energy here swings from a low near 0.52 kWh/m² to a high of 5.51 kWh/m² in June across the year — September's 2.98 kWh/m² falls in the middle.

01234151015202530
Solar energy (kWh/m²)Level
13.7Moderate
23.6Moderate
33.6Moderate
43.5Moderate
53.5Moderate
63.4Moderate
73.4Moderate
83.3Moderate
93.3Moderate
103.3Moderate
113.2Moderate
123.2Moderate
133.1Moderate
143.1Moderate
153.0Moderate
163.0Moderate
172.9Moderate
182.9Moderate
192.8Moderate
202.8Moderate
212.8Moderate
222.7Moderate
232.7Moderate
242.6Moderate
252.6Moderate
262.5Moderate
272.5Moderate
282.4Moderate
292.4Moderate
302.4Moderate
Planning a trip in September

Is September a good time to visit Siedlce?

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

5.7
Sightseeing
4th-best month of the year
2.0
Beach & pool
5th-best month of the year

September is a reasonable time to visit Siedlce for sightseeing.

What to pack for Siedlce in September

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

In September, Siedlce sees daytime highs around 18°C and nights near 9°C. Worth packing: rain gear. About 9 days see rain.

rain gear

UV index in Siedlce 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 Siedlce 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 20 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 20UV 1
UV index (midday)Level
Jan1Low
Feb1Low
Mar3Moderate
Apr4Moderate
May5High
Jun6High
Jul6High
Aug6High
Sep4Moderate
Oct2Low
Nov1Low
Dec1Low

Air quality in Siedlce 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 Siedlce is worst in March — around 24 µg/m³ PM2.5 (moderate), about 1.9× the cleanest month (December, 13 µg/m³).

Seasonal pattern from CAMS reanalysis, scaled to Siedlce's WHO annual average of 19.6 µg/m³.

0102030JanFebMarAprMayJunJulAugSepOctNovDecModerateMar 2424 µg/m³Dec 1613 µg/m³
PM2.5 (µg/m³)Level
Jan16Moderate
Feb18Moderate
Mar24Moderate
Apr24Moderate
May22Moderate
Jun24Moderate
Jul24Moderate
Aug21Moderate
Sep19Moderate
Oct16Moderate
Nov15Moderate
Dec13Moderate
Location & terrain

Where is Siedlce?

Siedlce sits at 52.2°N, 22.3°E, 155 m above sea level, in Poland. The nearest listed city is Sokołów Podlaski, 27 km away.

Międzyrzec PodlaskiRadzyń PodlaskiSiemiatyczeMińsk MazowieckiGarwolinBiała Podlaska

Topography around Siedlce

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

Within 3 km, the terrain around Siedlce has only modest variations in elevation — a maximum elevation change of 45 m around an average of 154 m above sea level; within 16 km, only modest variations in elevation — a maximum elevation change of 70 m; within 80 km, only modest variations in elevation — a maximum elevation change of 155 m.

The land around Siedlce is covered by artificial surfaces (36%), grassland (28%) and trees (24%) within 3 km, cropland (38%), trees (29%) and grassland (28%) within 16 km, and trees (38%), cropland (38%) and grassland (22%) within 80 km.

3 km
45 m
16 km
70 m
80 km
155 m
treesgrasslandcroplandartificial surfaceswaterwetland
September weather nearby: Sokołów Podlaski 27 km · Łuków 27 km · Międzyrzec Podlaski 39 km · Radzyń Podlaski 48 km · Siemiatycze 48 km · Mińsk Mazowiecki 49 km · Garwolin 55 km · Biała Podlaska 58 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 Siedlce (52.1677°, 22.2901°, elevation 155 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).