Setauket-East Setauket weather in September

In September, Setauket-East Setauket sees average daytime highs of 72°F and overnight lows near 64°F, with 3.8 in of rain across 9.1 wet days and about 12.3 hours of daylight. It is the 4th-warmest and 6th-wettest month of the year here.

Highs ease over the month, from about 75°F in the first days to 68°F by the end. The sky is clear or mostly clear about 41% of the time in September, and the air most often feels dry.

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 Setauket-East Setauket's 2nd-clearest and 8th-windiest month. For the whole year in context, see Setauket-East Setauket's year-round climate.

Daytime high
72°
4th warmest
Overnight low
64°
10th coldest
Rainfall
3.8 in
9.1 wet days
Daylight
12 h 18 min
5:39 AM – 5:55 PM
Cloud cover
53%
2nd clearest
Wind
9 mph
8th windiest
Solar energy
4.41 kWh/m²
Travel score
6.9
out of 10

Setauket-East Setauket is former census-designated place in Suffolk County, New York, United States.

Density
641/km²
people per km²

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 75°F in the first days to 68°F by the end.

A typical September day in Setauket-East Setauket reaches about 72°F in the afternoon and slips back to 64°F overnight — a 8°F spread between the day's warmth and the night's chill. On most days the high lands between 66°F and 77°F. Set against its neighbours, September runs about 6°F cooler than August and about 10°F warmer than October.

50°60°70°80°151015202530
Avg high (°F)Avg low (°F)
17668
27567
37567
47567
57567
67467
77466
87466
97466
107365
117365
127365
137365
147264
157264
167264
177264
187163
197163
207163
217062
227062
237062
246961
256961
266961
276960
286860
296860
306759

How September really feels in Setauket-East Setauket

Once humidity and wind are folded in, September averages 0 days that feel above 90°F and 0 that feel at or below 32°F — the comfort signal a plain temperature reading hides.

Days feeling ≥ 90°F
0
heat index over the day's high
Days feeling ≤ 32°F
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.

Setauket-East Setauket weather by month

How September compares with the rest of the year at a glance. September is the 4th-warmest and 6th-wettest month here — the current month is highlighted below.

MonthHigh / Low (°F)Rainfall (inches)Wet daysSnow daysDaylight (hours)Travel score
Jan38° / 29°3.79.74.29.40.0
Feb38° / 29°3.49.13.810.40.0
Mar44° / 35°4.610.63.311.70.7
Apr53° / 44°3.910.70.413.13.0
May63° / 53°3.510.8014.35.3
Jun72° / 64°3.69.7014.96.7
Jul78° / 70°3.29.2014.66.9
Aug78° / 70°4.09.5013.67.0
Sep72° / 64°3.89.1012.36.9
Oct62° / 54°4.49.40.110.95.5
Nov53° / 44°3.79.10.39.73.0
Dec44° / 35°4.810.62.49.10.7

Cloud cover in September

ClearMostly clearPartly cloudyMostly cloudyOvercast

The sky is clear or mostly clear about 41% of the time in September.

Beyond those clear spells, partly cloudy skies cover about 14% of September, with mostly cloudy or overcast conditions the remaining 45%.

0%25%50%75%100%151015202530
Clearer (%)Cloudier (%)
15743
25743
35644
45644
55644
65545
75545
85545
95644
105644
115644
125644
135644
145644
155545
165545
175446
185545
195446
205347
215347
225347
235248
245248
255248
265347
275347
285347
295347
305446

Chance of precipitation in September

Any precipitation

Setauket-East Setauket gets around 3.8 in of rain over 9.1 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 29% and peaks near 33% on the wettest days.

0%10%20%30%40%151015202530
Rain chance (%)
126
226
327
427
527
628
728
828
928
1028
1129
1229
1329
1429
1529
1629
1729
1829
1930
2030
2130
2231
2331
2432
2532
2632
2732
2832
2932
3033

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 29% of days. Sticky, muggy-or-worse air turns up on roughly 26% of them.

0%25%50%75%100%151015202530
Dry (%)Comfortable (%)Humid (%)Muggy (%)Oppressive (%)
11120282714
21220282713
31320272713
41420272612
51520272612
61721272511
71821262510
81921262410
9202126249
10222126248
11232125237
12242125237
13262125236
14272125225
15292125214
16302125214
17322125203
18332125193
19342125192
20352124182
21362124172
22382124171
23392123161
24402122151
25422122141
26432221141
27442220131
28462220121
29472219110
30492218110

Wind in September

Winds average 9 mph in September.

Across September, daily wind ranges from about 8 mph on the calmest days to 10 mph at its breeziest. It stays fairly steady from day to day.

051015151015202530
Wind speed (mph)Feels
18light breeze
28light breeze
38light breeze
49light breeze
59light breeze
69light breeze
79light breeze
89light breeze
99light breeze
109light breeze
119light breeze
129light breeze
139light breeze
149light breeze
159light breeze
169light breeze
179light breeze
189light breeze
199light breeze
209light breeze
219light breeze
229light breeze
239light breeze
249light breeze
259light breeze
269light breeze
2710light breeze
2810light breeze
2910light breeze
3010light breeze

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 5:23 AM to 5:53 AM, and sunset from 6:21 PM to 5:30 PM.

12 AM4 AM8 AM12 PM4 PM8 PM12 AM151015202530
Daylight (h)Sunrise (AM)Sunset (PM)
113.05:236:21
212.95:246:19
312.95:256:17
412.85:266:16
512.85:276:14
612.75:296:12
712.75:306:11
812.65:316:09
912.65:326:07
1012.55:336:05
1112.55:346:04
1212.55:356:02
1312.45:366:00
1412.45:375:58
1512.35:385:57
1612.35:395:55
1712.25:405:53
1812.25:415:51
1912.15:425:49
2012.15:435:48
2112.05:445:46
2212.05:455:44
2311.95:465:42
2411.95:475:41
2511.85:485:39
2611.85:495:37
2711.85:505:35
2811.75:515:34
2911.75:525:32
3011.65:535:30

Solar energy in September

Daily solar energy (kWh/m²)

Average shortwave solar energy reaching the ground each day in September, about 4.41 kWh/m².

For context, solar energy here swings from a low near 1.74 kWh/m² to a high of 6.34 kWh/m² in June across the year — September's 4.41 kWh/m² falls in the middle.

0246151015202530
Solar energy (kWh/m²)Level
15.0Bright
25.0Bright
35.0Bright
44.9Bright
54.9Bright
64.8Bright
74.8Bright
84.8Bright
94.7Bright
104.7Bright
114.6Bright
124.6Bright
134.5Bright
144.5Bright
154.5Bright
164.4Bright
174.4Bright
184.3Bright
194.3Bright
204.2Bright
214.2Bright
224.1Bright
234.1Bright
244.0Bright
254.0Moderate
264.0Moderate
273.9Moderate
283.9Moderate
293.8Moderate
303.8Moderate
Planning a trip in September

Hazard calendar for Setauket-East Setauket

In seasonPeak

In September, Setauket-East Setauket sits inside its atlantic hurricane season. The full year is below, with each hazard's peak months called out.

Setauket-East Setauket sits in the Atlantic hurricane belt; the season peaks August–October.

Atlantic hurricane
Jan
Feb
Mar
Apr
May
Jun
Jul
Aug
Sep
Oct
Nov
Dec

Is September a good time to visit Setauket-East Setauket?

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

6.9
Sightseeing
2nd-best month of the year
4.9
Beach & pool
3rd-best month of the year

September is a reasonable time to visit Setauket-East Setauket for sightseeing.

What to pack for Setauket-East Setauket in September

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

In September, Setauket-East Setauket sees daytime highs around 72°F and nights near 64°F. Worth packing: light clothes and rain gear. About 9 days see rain.

light clothesrain gear

Sea temperature near Setauket-East Setauket in September

The nearest coast averages about 71°F 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 14 mi away) is warmest in August at about 74°F and coldest in February near 35°F.

It's comfortable for a long swim from Jul 1 to Sep 30 — about 3 months when the water holds above 68°F.

30°40°50°60°70°80°JanFebMarAprMayJunJulAugSepOctNovDecbracingcoolrefreshingwarmtropicalcomfortable to swim
Sea temperature (°F)Comfort
Jan39Bracing
Feb35Bracing
Mar37Bracing
Apr44Bracing
May54Bracing
Jun65Cool
Jul72Refreshing
Aug74Refreshing
Sep71Refreshing
Oct64Cool
Nov55Bracing
Dec46Bracing

UV index in Setauket-East Setauket 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 Setauket-East Setauket peaks around July 11 at about 8 (very high) — sunscreen and a hat are worth it in the middle of the day. It bottoms out near December 22 at about 1 (low).

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

025710JanFebMarAprMayJunJulAugSepOctNovDecLowModerateHighVery highHighModerateLowJul 11UV 8Dec 22UV 1
UV index (midday)Level
Jan2Low
Feb3Moderate
Mar5Moderate
Apr6High
May7Very high
Jun8Very high
Jul8Very high
Aug6High
Sep6High
Oct3Moderate
Nov2Moderate
Dec1Low

Air quality in Setauket-East Setauket 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 Setauket-East Setauket is worst in July — around 20 µg/m³ PM2.5 (moderate), about 2.7× the cleanest month (November, 8 µg/m³).

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

0102030JanFebMarAprMayJunJulAugSepOctNovDecGoodModerateGoodJul 1120 µg/m³Nov 188 µg/m³
PM2.5 (µg/m³)Level
Jan10Good
Feb13Moderate
Mar14Moderate
Apr16Moderate
May19Moderate
Jun20Moderate
Jul20Moderate
Aug17Moderate
Sep13Moderate
Oct9Good
Nov8Good
Dec9Good
Location & terrain

Where is Setauket-East Setauket?

Setauket-East Setauket sits at 40.9°N, 73.1°W, 102 ft above sea level, in United States. The nearest listed city is East Setauket, 0.6 mi away.

Topography around Setauket-East Setauket

How much the land rises and falls, and what covers it, within 2, 10 and 50 miles of Setauket-East Setauket.

Within 2 miles, the terrain around Setauket-East Setauket has only modest variations in elevation — a maximum elevation change of 285 ft around an average of 121 ft above sea level; within 10 miles, only modest variations in elevation — a maximum elevation change of 338 ft; within 50 miles, significant variations in elevation — a maximum elevation change of 1,457 ft.

The land around Setauket-East Setauket is covered by trees (77%) within 2 miles, water (45%) and trees (42%) within 10 miles, and water (47%) and trees (41%) within 50 miles.

2 miles
285 ft
10 miles
338 ft
50 miles
1,457 ft
treesgrasslandartificial surfaceswaterwetland
September weather nearby: East Setauket 0.6 mi · Centereach 5.0 mi · Selden 5.6 mi · Coram 6.8 mi · Lake Ronkonkoma 6.8 mi · Smithtown 7.5 mi · Farmingville 8.1 mi · Ronkonkoma 8.1 mi

United States travel facts

Power plugs
Type A / B
120 V · 60 Hz
Prices
≈ 100% of US
price level, 2025
GDP per capita
$90,027
2025
Happiness
6.8 / 10
World Happiness, 2025
Safe drinking water
98%
of population, 2024
Homicide rate
5.8
per 100k, 2023
Road deaths
12.7
per 100k/yr, 2019
Income group
High
World Bank
Religion
Protestant 47%unaffiliated 23%Roman Catholic 21%Jewish 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 Setauket-East Setauket (40.9306°, -73.1018°, elevation 102 ft), 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. Tropical-cyclone seasons are the published climatological basin seasons (NOAA National Hurricane Center / regional warning centres). 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).