İzmit weather in September

In September, İzmit sees average daytime highs of 24°C and overnight lows near 15°C, with 61 mm of rain across 8.4 wet days and about 12.3 hours of daylight. It is the 4th-warmest and 10th-wettest month of the year here.

Highs ease over the month, from about 26°C in the first days to 23°C by the end. The sky is clear or mostly clear about 53% of the time in September, and the air most often feels comfortable.

Daylight stretches from about 13 hours at the start of September to 11 h 36 min by month's end. Set against the rest of the year, September is İzmit's 4th-clearest and 6th-windiest month. For the whole year in context, see İzmit's year-round climate.

Daytime high
24°
4th warmest
Overnight low
15°
9th coldest
Rainfall
61 mm
8.4 wet days
Daylight
12 h 18 min
5:47 AM – 6:03 PM
Cloud cover
40%
4th clearest
Wind
7 km/h
6th windiest
Solar energy
4.5 kWh/m²
Travel score
7.4
out of 10

İzmit is ancient city of Bithynia in modern-day Turkey.

Founded
~263 BCE

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 26°C in the first days to 23°C by the end.

A typical September day in İzmit reaches about 24°C in the afternoon and slips back to 15°C overnight — a 10°C spread between the day's warmth and the night's chill. On most days the high lands between 19°C and 29°C. Set against its neighbours, September runs about 3°C cooler than August and about 5°C warmer than October.

10°20°30°151015202530
Avg high (°C)Avg low (°C)
12617
22616
32616
42616
52616
62516
72516
82516
92515
102515
112515
122515
132515
142415
152415
162415
172415
182415
192414
202414
212414
222314
232314
242314
252314
262314
272313
282313
292213
302213

How September really feels in İzmit

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.

İzmit weather by month

How September compares with the rest of the year at a glance. September is the 4th-warmest and 10th-wettest month here — the current month is highlighted below.

MonthHigh / Low (°C)Rainfall (mm)Wet daysSnow daysDaylight (hours)Travel score
Jan / 101147.29.40.9
Feb / 8913.26.110.41.5
Mar12° / 9813.63.711.72.8
Apr16° / 7611.70.713.15.0
May21° / 11°7310.9014.26.5
Jun25° / 15°7610.6014.97.1
Jul27° / 18°436.4014.67.6
Aug27° / 18°416.5013.67.5
Sep24° / 15°618.4012.37.4
Oct19° / 11°9011.1010.96.1
Nov14° / 8010.41.29.74.0
Dec / 11013.34.39.11.6

Cloud cover in September

ClearMostly clearPartly cloudyMostly cloudyOvercast

The sky is clear or mostly clear about 53% of the time in September.

Beyond those clear spells, partly cloudy skies cover about 19% of September, with mostly cloudy or overcast conditions the remaining 29%. Skies tend to cloud over as the month goes on.

0%25%50%75%100%151015202530
Clearer (%)Cloudier (%)
17921
27921
37921
47822
57822
67723
77723
87822
97723
107624
117624
127525
137426
147426
157228
167228
177129
187030
196931
206832
216733
226634
236634
246535
256436
266337
276337
286238
296238
306139

Chance of precipitation in September

Any precipitation

İzmit gets around 61 mm of rain over 8.4 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 28% and peaks near 32% on the wettest days.

0%10%20%30%40%151015202530
Rain chance (%)
127
227
327
427
527
626
726
825
925
1024
1124
1224
1324
1424
1525
1625
1726
1826
1927
2028
2129
2230
2331
2431
2532
2632
2732
2832
2932
3032

Humidity in September

DryComfortableHumidMuggyOppressiveMiserable

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

By dew point, September lands in the comfortable band about 37% of days. Sticky, muggy-or-worse air turns up on roughly 8% of them.

0%25%50%75%100%151015202530
Dry (%)Comfortable (%)Humid (%)Muggy (%)
110274221
211284120
312294118
413304016
514313915
615333913
716333912
816343811
917353810
101736389
111836378
121837377
131937377
142038366
152038366
162139355
172239345
182339335
192439325
202540314
212740304
222840283
233040273
243240263
253340242
263540232
273640222
283840211
293940201
304040181

Wind in September

Winds average 7 km/h in September.

Across September, daily wind ranges from about 7 km/h on the calmest days to 8 km/h at its breeziest. It stays fairly steady from day to day.

0246810151015202530
Wind speed (km/h)Feels
18calm
28calm
38calm
48calm
58calm
68calm
78calm
88calm
98calm
108calm
118calm
128calm
137calm
147calm
157calm
167calm
177calm
187calm
197calm
207calm
217calm
227calm
237calm
247calm
257calm
267calm
277calm
287calm
297calm
307calm

Sunrise & sunset in September

DaylightNight

Daylight runs from about 13 hours at the start of September to 11 h 36 min by month's end. The lit band spans sunrise to sunset each day.

Days shrink by about 84 minutes over September. Sunrise moves from 5:31 AM to 6:01 AM, and sunset from 6:29 PM to 5:38 PM.

12 AM4 AM8 AM12 PM4 PM8 PM12 AM151015202530
Daylight (h)Sunrise (AM)Sunset (PM)
113.05:316:29
212.95:326:27
312.95:336:25
412.85:346:23
512.85:356:22
612.75:376:20
712.75:386:18
812.65:396:17
912.65:406:15
1012.55:416:13
1112.55:426:11
1212.55:436:10
1312.45:446:08
1412.45:456:06
1512.35:466:04
1612.35:476:03
1712.25:486:01
1812.25:495:59
1912.15:505:57
2012.15:515:56
2112.05:525:54
2212.05:535:52
2311.95:545:50
2411.95:555:49
2511.85:565:47
2611.85:575:45
2711.85:585:43
2811.75:595:42
2911.76:005:40
3011.66:015:38

Solar energy in September

Daily solar energy (kWh/m²)

Average shortwave solar energy reaching the ground each day in September, about 4.5 kWh/m².

For context, solar energy here swings from a low near 1.52 kWh/m² to a high of 6.71 kWh/m² in July across the year — September's 4.5 kWh/m² falls in the middle.

0246151015202530
Solar energy (kWh/m²)Level
15.2Bright
25.2Bright
35.1Bright
45.1Bright
55.0Bright
65.0Bright
74.9Bright
84.9Bright
94.8Bright
104.8Bright
114.8Bright
124.7Bright
134.7Bright
144.6Bright
154.5Bright
164.5Bright
174.4Bright
184.4Bright
194.3Bright
204.3Bright
214.2Bright
224.2Bright
234.1Bright
244.1Bright
254.0Bright
264.0Moderate
273.9Moderate
283.9Moderate
293.8Moderate
303.8Moderate
Planning a trip in September

Is September a good time to visit İzmit?

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

7.4
Sightseeing
3rd-best month of the year
6.3
Beach & pool
3rd-best month of the year

September is one of the better times to visit İzmit for general sightseeing. The water and warmth also suit a beach or pool day.

What to pack for İzmit in September

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

In September, İzmit sees daytime highs around 24°C and nights near 15°C. Worth packing: light clothes, rain gear and sun protection. About 8 days see rain.

light clothesrain gearsun protection

Sea temperature near İzmit in September

The nearest coast averages about 23°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 40 km away) is warmest in August at about 25°C and coldest in February near 7°C.

It's comfortable for a long swim from Jun 11 to Oct 10 — about 4 months when the water holds above 20°C.

10°20°30°JanFebMarAprMayJunJulAugSepOctNovDecbracingcoolrefreshingwarmtropicalcomfortable to swim
Sea temperature (°C)Comfort
Jan9Bracing
Feb7Bracing
Mar8Bracing
Apr10Bracing
May16Cool
Jun21Refreshing
Jul24Warm
Aug25Warm
Sep23Refreshing
Oct19Cool
Nov15Cool
Dec11Bracing

UV index in İzmit in September

LowModerateHighVery highExtreme

Clear-sky midday UV in September 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 İzmit peaks around June 23 at about 9 (very high) — sunscreen, a hat and midday shade are essential. It bottoms out near December 21 at about 2 (low).

The index reaches 3 or more — the level where the WHO recommends sun protection — in 8 months of the year.

025710JanFebMarAprMayJunJulAugSepOctNovDecLowModerateHighVery highHighModerateLowJun 23UV 9Dec 21UV 2
UV index (midday)Level
Jan2Low
Feb2Moderate
Mar4Moderate
Apr7High
May7High
Jun9Very high
Jul9Very high
Aug9Very high
Sep6High
Oct4Moderate
Nov2Moderate
Dec2Low

Air quality in İzmit 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 İzmit is worst in March — around 16 µg/m³ PM2.5 (moderate), about 2.0× the cleanest month (December, 8 µg/m³).

Modeled monthly averages (CAMS reanalysis, 2015–2024).

01020JanFebMarAprMayJunJulAugSepOctNovDecGoodModerateGoodMar 2316 µg/m³Dec 198 µg/m³
PM2.5 (µg/m³)Level
Jan9Good
Feb11Good
Mar16Moderate
Apr16Moderate
May15Moderate
Jun13Moderate
Jul10Good
Aug10Good
Sep10Good
Oct10Good
Nov10Good
Dec8Good
Location & terrain

Where is İzmit?

İzmit sits at 40.8°N, 29.9°E, 19 m above sea level, in Turkey. The nearest listed city is Derince, 10 km away.

Topography around İzmit

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

Within 3 km, the terrain around İzmit has significant variations in elevation — a maximum elevation change of 272 m around an average of 60 m above sea level; within 16 km, large variations in elevation — a maximum elevation change of 991 m; within 80 km, very significant variations in elevation — a maximum elevation change of 1,739 m.

The land around İzmit is covered by artificial surfaces (48%) and water (26%) within 3 km, trees (54%) within 16 km, and trees (51%) and water (24%) within 80 km.

3 km
272 m
16 km
991 m
80 km
1,739 m
treesgrasslandcroplandartificial surfacesbare terrainwater
September weather nearby: Derince 10 km · Gölcük 11 km · Körfez 12 km · Karamürsel 28 km · Sapanca 30 km · Kandıra 39 km · Adapazarı 40 km · İznik 41 km

Turkey travel facts

Travel advisory
Level 2
Exercise Increased Caution
Power plugs
Type C / F
230 V · 50 Hz
Prices
≈ 41% of US
price level, 2025
GDP per capita
$18,599
2025
Happiness
5.3 / 10
World Happiness, 2025
Homicide rate
3.2
per 100k, 2023
Road deaths
6.7
per 100k/yr, 2019
Income group
Upper middle
World Bank
English
Low
EF EPI 488
Religion
Muslim 100%other 0%

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 İzmit (40.765°, 29.9293°, elevation 19 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. 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).