Bar Harbor weather in September

In September, Bar Harbor sees average daytime highs of 66°F and overnight lows near 54°F, with 3.7 in of rain across 7.9 wet days and about 12.3 hours of daylight. It is the 4th-warmest and 7th-wettest month of the year here.

Highs ease over the month, from about 69°F in the first days to 62°F by the end. The sky is clear or mostly clear about 37% of the time in September, and the air most often feels dry.

Daylight stretches from about 13 h 06 min at the start of September to 11 h 36 min by month's end. Set against the rest of the year, September is Bar Harbor's 1st-clearest and 9th-windiest month. For the whole year in context, see Bar Harbor's year-round climate.

Daytime high
66°
4th warmest
Overnight low
54°
10th coldest
Rainfall
3.7 in
7.9 wet days
Daylight
12 h 18 min
5:18 AM – 5:36 PM
Cloud cover
55%
1st clearest
Wind
8 mph
9th windiest
Solar energy
4.09 kWh/m²
Travel score
6.3
out of 10

Bar Harbor is town in Hancock County, Maine, United States.

Air quality
Excellent
PM10 5.1 µg/m³ · 2019
Founded
1763

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 69°F in the first days to 62°F by the end.

A typical September day in Bar Harbor reaches about 66°F in the afternoon and slips back to 54°F overnight — a 12°F spread between the day's warmth and the night's chill. On most days the high lands between 60°F and 72°F. Set against its neighbours, September runs about 6°F cooler than August and about 10°F warmer than October.

40°50°60°70°80°151015202530
Avg high (°F)Avg low (°F)
17058
27058
36957
46957
56957
66957
76856
86856
96856
106756
116755
126755
136655
146655
156654
166554
176554
186554
196553
206453
216453
226453
236452
246352
256352
266251
276251
286251
296251
306150

How September really feels in Bar Harbor

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.

Bar Harbor weather by month

How September compares with the rest of the year at a glance. September is the 4th-warmest and 7th-wettest month here — the current month is highlighted below.

MonthHigh / Low (°F)Rainfall (inches)Wet daysSnow daysDaylight (hours)Travel score
Jan30° / 16°3.910.27.790.0
Feb31° / 17°3.39.3710.10.0
Mar38° / 25°3.910.6611.60.0
Apr48° / 37°3.811.42.413.21.6
May57° / 46°3.311014.63.9
Jun66° / 54°3.610.1015.35.9
Jul72° / 60°2.8100156.7
Aug72° / 60°2.88.3013.87.0
Sep66° / 54°3.77.9012.36.3
Oct56° / 45°4.79.90.210.83.7
Nov45° / 35°4.3101.59.41.1
Dec35° / 24°4.811.66.28.70.0

Cloud cover in September

ClearMostly clearPartly cloudyMostly cloudyOvercast

The sky is clear or mostly clear about 37% of the time in September, the clearest month of the year.

Beyond those clear spells, partly cloudy skies cover about 15% of September, with mostly cloudy or overcast conditions the remaining 48%.

0%25%50%75%100%151015202530
Clearer (%)Cloudier (%)
15545
25545
35446
45446
55446
65347
75347
85347
95347
105347
115347
125248
135248
145347
155248
165248
175149
185149
195149
205149
215050
225050
235050
245050
255050
265050
274951
285050
295050
304951

Chance of precipitation in September

Any precipitation

Bar Harbor gets around 3.7 in of rain over 7.9 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 26% and peaks near 31% on the wettest days.

0%10%20%30%40%151015202530
Rain chance (%)
124
224
325
425
525
626
726
826
926
1026
1126
1226
1326
1425
1525
1625
1725
1825
1926
2026
2126
2226
2327
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 57% of days. It rarely turns muggy — the humid and sticky bands barely register.

0%25%50%75%100%151015202530
Dry (%)Comfortable (%)Humid (%)Muggy (%)
13635235
23835235
33934224
44134214
54233214
64433204
74532193
84732193
94831183
105030182
115229172
125229172
135428162
145627161
155727151
165926141
175926141
186225130
196324130
206424120
216523120
226722110
236821110
246921100
257020100
26721990
27741880
28751780
29771670
30781570

Wind in September

Winds average 8 mph in September.

Across September, daily wind ranges from about 8 mph on the calmest days to 9 mph at its breeziest. It stays fairly steady from day to day.

051015151015202530
Wind speed (mph)Feels
18light breeze
28light breeze
38light breeze
48light breeze
58light breeze
68light breeze
78light breeze
88light breeze
98light breeze
108light breeze
118light breeze
128light breeze
138light breeze
148light breeze
158light breeze
168light breeze
178light breeze
188light breeze
198light breeze
208light breeze
218light breeze
228light breeze
238light breeze
249light breeze
259light breeze
269light breeze
279light breeze
289light breeze
299light breeze
309light breeze

Sunrise & sunset in September

DaylightNight

Daylight runs from about 13 h 06 min 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 90 minutes over September. Sunrise moves from 5:00 AM to 5:35 AM, and sunset from 6:05 PM to 5:09 PM.

12 AM4 AM8 AM12 PM4 PM8 PM12 AM151015202530
Daylight (h)Sunrise (AM)Sunset (PM)
113.15:006:05
213.05:016:03
313.05:026:01
412.95:045:59
512.95:055:57
612.85:065:56
712.85:075:54
812.75:085:52
912.75:105:50
1012.65:115:48
1112.65:125:46
1212.55:135:44
1312.55:145:42
1412.45:165:40
1512.45:175:38
1612.35:185:36
1712.35:195:34
1812.25:205:32
1912.15:225:30
2012.15:235:28
2112.05:245:26
2212.05:255:25
2311.95:275:23
2411.95:285:21
2511.85:295:19
2611.85:305:17
2711.75:315:15
2811.75:335:13
2911.65:345:11
3011.65:355:09

Solar energy in September

Daily solar energy (kWh/m²)

Average shortwave solar energy reaching the ground each day in September, about 4.09 kWh/m².

For context, solar energy here swings from a low near 1.41 kWh/m² to a high of 5.84 kWh/m² in July across the year — September's 4.09 kWh/m² falls in the middle.

024151015202530
Solar energy (kWh/m²)Level
14.8Bright
24.7Bright
34.7Bright
44.6Bright
54.6Bright
64.5Bright
74.5Bright
84.5Bright
94.4Bright
104.3Bright
114.3Bright
124.3Bright
134.2Bright
144.2Bright
154.1Bright
164.1Bright
174.0Bright
184.0Moderate
194.0Moderate
203.9Moderate
213.9Moderate
223.8Moderate
233.8Moderate
243.7Moderate
253.7Moderate
263.6Moderate
273.6Moderate
283.5Moderate
293.5Moderate
303.4Moderate
Planning a trip in September

Hazard calendar for Bar Harbor

In seasonPeak

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

Bar Harbor 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 Bar Harbor?

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

6.3
Sightseeing
3rd-best month of the year
2.6
Beach & pool
3rd-best month of the year

September is a reasonable time to visit Bar Harbor for sightseeing.

What to pack for Bar Harbor in September

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

In September, Bar Harbor sees daytime highs around 66°F and nights near 54°F. Little to plan around — just the basics. About 8 days see rain.

Sea temperature near Bar Harbor in September

The nearest coast averages about 54°F in September — the other half of the beach question. The full-year curve and swim-comfort zones are below.

The sea offshore is warmest in August at about 55°F and coldest in March near 38°F.

The water stays below 68°F all year — cool enough that most swimmers want a wetsuit.

40°50°60°JanFebMarAprMayJunJulAugSepOctNovDecbracingcool
Sea temperature (°F)Comfort
Jan42Bracing
Feb39Bracing
Mar38Bracing
Apr40Bracing
May44Bracing
Jun48Bracing
Jul53Bracing
Aug55Bracing
Sep54Bracing
Oct52Bracing
Nov49Bracing
Dec46Bracing

UV index in Bar Harbor in September

LowModerateHighVery highExtreme

Clear-sky midday UV in September peaks around 5 — enough to warrant sun protection. The full-year curve, shaded by WHO exposure level, is below.

Under clear skies, the midday UV index in Bar Harbor peaks around July 13 at about 7 (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 7 months of the year.

025710JanFebMarAprMayJunJulAugSepOctNovDecLowModerateHighModerateModerateLowJul 13UV 7Dec 22UV 1
UV index (midday)Level
Jan1Low
Feb2Low
Mar4Moderate
Apr5High
May7High
Jun6High
Jul8Very high
Aug4Moderate
Sep5High
Oct3Moderate
Nov2Low
Dec1Low
Location & terrain

Where is Bar Harbor?

Bar Harbor sits at 44.4°N, 68.2°W, 0 ft above sea level, in United States. The nearest listed city is Bangor, 40 mi away.

Topography around Bar Harbor

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

Within 2 miles, the terrain around Bar Harbor has significant variations in elevation — a maximum elevation change of 938 ft around an average of 105 ft above sea level; within 10 miles, significant variations in elevation — a maximum elevation change of 1,526 ft; within 50 miles, significant variations in elevation — a maximum elevation change of 1,516 ft.

The land around Bar Harbor is covered by water (52%) and trees (41%) within 2 miles, water (48%) and trees (47%) within 10 miles, and water (49%) and trees (47%) within 50 miles.

2 miles
938 ft
10 miles
1,526 ft
50 miles
1,516 ft
treesgrasslandartificial surfaceswaterwetland
September weather nearby: Bangor 40 mi · Waterville 71 mi · Augusta 78 mi · Brunswick 93 mi · Lewiston 101 mi · Auburn 103 mi · South Portland 114 mi · Portland 114 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 Bar Harbor (44.3876°, -68.2039°, elevation 0 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. Topography is sampled from the Copernicus DEM GLO-90 elevation model (© ESA/Airbus) and ESA WorldCover 2021 land cover (CC BY 4.0).