New Haven weather in September

In September, New Haven sees average daytime highs of 72°F and overnight lows near 62°F, with 4.3 in of rain across 8.9 wet days and about 12.3 hours of daylight. It is the 3rd-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 40% 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 New Haven's 2nd-clearest and 8th-windiest month. For the whole year in context, see New Haven's year-round climate.

Daytime high
72°
3rd warmest
Overnight low
62°
10th coldest
Rainfall
4.3 in
8.9 wet days
Daylight
12 h 18 min
5:38 AM – 5:54 PM
Cloud cover
53%
2nd clearest
Wind
9 mph
8th windiest
Solar energy
4.31 kWh/m²
Travel score
6.9
out of 10

New Haven is city in Connecticut, United States.

Density
2,500/km²
people per km²
Founded
1638

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 New Haven reaches about 72°F in the afternoon and slips back to 62°F overnight — a 10°F spread between the day's warmth and the night's chill. On most days the high lands between 65°F and 78°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)
17566
27566
37565
47565
57465
67465
77465
87464
97464
107364
117364
127363
137363
147263
157262
167262
177162
187162
197161
207061
217061
227060
236960
246960
256959
266959
276859
286858
296758
306758

How September really feels in New Haven

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.

New Haven weather by month

How September compares with the rest of the year at a glance. September is the 3rd-warmest and 6th-wettest month here — the current month is highlighted below.

MonthHigh / Low (°F)Rainfall (inches)Wet daysSnow daysDaylight (hours)Travel score
Jan37° / 27°4.310.14.99.40.0
Feb37° / 27°3.89.14.310.30.0
Mar43° / 33°5.110.93.411.70.5
Apr53° / 42°4.611.50.513.12.8
May62° / 52°3.911.6014.35.1
Jun72° / 62°3.910.5014.96.5
Jul78° / 68°3.29.5014.76.9
Aug77° / 68°4.09.6013.77.0
Sep72° / 62°4.38.9012.36.9
Oct62° / 52°5.110.10.110.95.3
Nov51° / 42°4.39.50.69.72.6
Dec42° / 34°5.411.23.39.10.4

Cloud cover in September

ClearMostly clearPartly cloudyMostly cloudyOvercast

The sky is clear or mostly clear about 40% 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 45%.

0%25%50%75%100%151015202530
Clearer (%)Cloudier (%)
15743
25743
35644
45644
55545
65644
75644
85644
95644
105644
115644
125644
135743
145644
155644
165545
175545
185446
195446
205446
215347
225347
235347
245347
255347
265446
275446
285446
295446
305446

Chance of precipitation in September

Any precipitation

New Haven gets around 4.3 in of rain over 8.9 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. The odds climb toward the end of the month.

0%10%20%30%40%151015202530
Rain chance (%)
126
226
327
427
527
627
728
828
928
1028
1128
1229
1329
1429
1529
1629
1729
1829
1930
2030
2130
2231
2331
2431
2532
2632
2732
2833
2933
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 34% of days. Sticky, muggy-or-worse air turns up on roughly 22% of them.

0%25%50%75%100%151015202530
Dry (%)Comfortable (%)Humid (%)Muggy (%)Oppressive (%)
11624252610
2172424259
3182424259
4192424249
5202423249
6212423238
7222423228
8242423227
9252422227
10262422216
11282422216
12292421205
13302421205
14322421194
15332421194
16352420183
17362320183
18372320172
19382320172
20392320162
21412320151
22422319151
23432319141
24452319131
25462318131
26472318121
27492218110
28502218100
29512217100
3053211790

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
39light 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
2410light breeze
2510light breeze
2610light 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 5:22 AM to 5:53 AM, and sunset from 6:21 PM to 5:29 PM.

12 AM4 AM8 AM12 PM4 PM8 PM12 AM151015202530
Daylight (h)Sunrise (AM)Sunset (PM)
113.05:226:21
212.95:236:19
312.95:246:17
412.85:256:15
512.85:266:14
612.75:286:12
712.75:296:10
812.65:306:08
912.65:316:07
1012.65:326:05
1112.55:336:03
1212.55:346:01
1312.45:356:00
1412.45:365:58
1512.35:375:56
1612.35:385:54
1712.25:395:52
1812.25:405:51
1912.15:415:49
2012.15:425:47
2112.05:435:45
2212.05:445:43
2311.95:455:42
2411.95:465:40
2511.85:475:38
2611.85:485:36
2711.85:495:35
2811.75:515:33
2911.75:525:31
3011.65:535:29

Solar energy in September

Daily solar energy (kWh/m²)

Average shortwave solar energy reaching the ground each day in September, about 4.31 kWh/m².

For context, solar energy here swings from a low near 1.71 kWh/m² to a high of 6.18 kWh/m² in June across the year — September's 4.31 kWh/m² falls in the middle.

024151015202530
Solar energy (kWh/m²)Level
14.9Bright
24.9Bright
34.9Bright
44.8Bright
54.8Bright
64.7Bright
74.7Bright
84.6Bright
94.6Bright
104.6Bright
114.5Bright
124.5Bright
134.4Bright
144.4Bright
154.4Bright
164.3Bright
174.3Bright
184.2Bright
194.2Bright
204.2Bright
214.1Bright
224.1Bright
234.0Bright
244.0Moderate
253.9Moderate
263.9Moderate
273.8Moderate
283.8Moderate
293.7Moderate
303.7Moderate
Planning a trip in September

Hazard calendar for New Haven

In seasonPeak

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

New Haven 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 New Haven?

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
4.8
Beach & pool
3rd-best month of the year

September is a reasonable time to visit New Haven for sightseeing.

What to pack for New Haven in September

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

In September, New Haven sees daytime highs around 72°F and nights near 62°F. Worth packing: light clothes and rain gear. About 9 days see rain.

light clothesrain gear

Sea temperature near New Haven 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 13 mi away) is warmest in August at about 73°F and coldest in February near 36°F.

It's comfortable for a long swim from Jul 4 to Sep 28 — about 2.9 months when the water holds above 68°F.

30°40°50°60°70°80°JanFebMarAprMayJunJulAugSepOctNovDecbracingcoolrefreshingwarmtropicalcomfortable to swim
Sea temperature (°F)Comfort
Jan39Bracing
Feb36Bracing
Mar37Bracing
Apr44Bracing
May54Bracing
Jun64Cool
Jul71Refreshing
Aug73Refreshing
Sep71Refreshing
Oct64Cool
Nov55Bracing
Dec46Bracing

UV index in New Haven 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 New Haven 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 9 months of the year.

025710JanFebMarAprMayJunJulAugSepOctNovDecModerateHighVery 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 New Haven 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 New Haven 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 New Haven?

New Haven sits at 41.3°N, 72.9°W, 59 ft above sea level, in United States. The nearest listed city is West Haven, 2.5 mi away.

Topography around New Haven

How much the land rises and falls, and what covers it, within 2, 10 and 50 miles of New Haven.

Within 2 miles, the terrain around New Haven has only modest variations in elevation — a maximum elevation change of 358 ft around an average of 43 ft above sea level; within 10 miles, significant variations in elevation — a maximum elevation change of 863 ft; within 50 miles, significant variations in elevation — a maximum elevation change of 1,752 ft.

The land around New Haven is covered by artificial surfaces (47%) and trees (32%) within 2 miles, trees (56%) and water (25%) within 10 miles, and trees (62%) and water (29%) within 50 miles.

2 miles
358 ft
10 miles
863 ft
50 miles
1,752 ft
treesgrasslandcroplandartificial surfaceswaterwetland
September weather nearby: West Haven 2.5 mi · East Haven 3.7 mi · Branford 6.2 mi · Hamden 6.2 mi · North Haven 6.8 mi · Ansonia 8.1 mi · Shelton 8.7 mi · Milford 8.7 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 New Haven (41.3081°, -72.9282°, elevation 59 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).