Mackinac Island weather in September

In September, Mackinac Island sees average daytime highs of 66°F and overnight lows near 55°F, with 3.5 in of rain across 11.4 wet days and about 12.3 hours of daylight. It is the 4th-warmest and 2nd-wettest month of the year here.

Highs ease over the month, from about 70°F in the first days to 62°F by the end. The sky is clear or mostly clear about 34% 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 30 min by month's end. Set against the rest of the year, September is Mackinac Island's 3rd-clearest and 7th-windiest month. For the whole year in context, see Mackinac Island's year-round climate.

Daytime high
66°
4th warmest
Overnight low
55°
9th coldest
Rainfall
3.5 in
11.4 wet days
Daylight
12 h 18 min
6:23 AM – 6:42 PM
Cloud cover
56%
3rd clearest
Wind
10 mph
7th windiest
Solar energy
4.1 kWh/m²
Travel score
5.9
out of 10

Mackinac Island is city located on Mackinac Island in Michigan.

Founded
1671

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 70°F in the first days to 62°F by the end.

A typical September day in Mackinac Island reaches about 66°F in the afternoon and slips back to 55°F overnight — a 11°F spread between the day's warmth and the night's chill. On most days the high lands between 57°F and 76°F. Set against its neighbours, September runs about 7°F cooler than August and about 12°F warmer than October.

40°50°60°70°80°151015202530
Avg high (°F)Avg low (°F)
17159
27159
37059
47058
57058
66958
76958
86957
96957
106857
116856
126856
136756
146756
156755
166655
176655
186655
196554
206554
216553
226453
236453
246453
256352
266352
276251
286251
296151
306150

How September really feels in Mackinac Island

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.

Mackinac Island weather by month

How September compares with the rest of the year at a glance. September is the 4th-warmest and 2nd-wettest month here — the current month is highlighted below.

MonthHigh / Low (°F)Rainfall (inches)Wet daysSnow daysDaylight (hours)Travel score
Jan24° / 14°1.99.910.98.90.0
Feb24° / 13°1.67.47.310.10.0
Mar33° / 21°2.08.46.111.60.0
Apr44° / 32°2.99.73.213.30.9
May56° / 43°2.910.20.314.73.7
Jun68° / 55°3.010015.56.3
Jul74° / 62°3.310.9015.26.9
Aug73° / 62°3.410013.96.9
Sep66° / 55°3.511.4012.35.9
Oct54° / 44°3.713.50.210.73.0
Nov42° / 34°2.611.65.79.30.5
Dec32° / 24°2.311.311.38.50.0

Cloud cover in September

ClearMostly clearPartly cloudyMostly cloudyOvercast

The sky is clear or mostly clear about 34% of the time in September.

Beyond those clear spells, partly cloudy skies cover about 17% of September, with mostly cloudy or overcast conditions the remaining 48%. Skies tend to cloud over as the month goes on.

0%25%50%75%100%151015202530
Clearer (%)Cloudier (%)
15743
25743
35644
45644
55743
65743
75644
85644
95545
105545
115545
125545
135446
145446
155248
165248
175248
185149
195050
205050
214951
224852
234753
244654
254555
264555
274456
284555
294555
304357

Chance of precipitation in September

Any precipitation

Mackinac Island gets around 3.5 in of rain over 11.4 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 37% and peaks near 40% on the wettest days.

0%10%20%30%40%50%151015202530
Rain chance (%)
134
234
334
435
535
635
736
836
936
1036
1136
1236
1337
1437
1537
1637
1737
1838
1938
2038
2138
2239
2339
2439
2540
2640
2740
2840
2940
3040

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 (%)
134312411
235312311
337302310
439302210
54029219
64229218
74428208
84628207
94727196
104927196
115126185
125226184
135326174
145526163
155526163
165725153
175925142
185925142
196124132
206323122
216423112
226622102
23682192
24702082
25721972
26741862
27761752
28781642
29791542
30811432

Wind in September

Winds average 10 mph in September.

Across September, daily wind ranges from about 9 mph on the calmest days to 11 mph at its breeziest. It stays fairly steady from day to day.

051015151015202530
Wind speed (mph)Feels
19light breeze
29light breeze
39light breeze
49light breeze
59light breeze
69light breeze
79light breeze
89light breeze
910light breeze
1010light breeze
1110light breeze
1210light breeze
1310light breeze
1410light breeze
1510light breeze
1610light breeze
1710light breeze
1810light breeze
1910light breeze
2010light breeze
2110light breeze
2210light breeze
2310light breeze
2410light breeze
2510light breeze
2610light breeze
2711light breeze
2811light breeze
2911light breeze
3011light breeze

Sunrise & sunset in September

DaylightNight

Daylight runs from about 13 h 06 min at the start of September to 11 h 30 min by month's end. The lit band spans sunrise to sunset each day.

Days shrink by about 96 minutes over September. Sunrise moves from 6:04 AM to 6:41 AM, and sunset from 7:12 PM to 6:14 PM.

12 AM4 AM8 AM12 PM4 PM8 PM12 AM151015202530
Daylight (h)Sunrise (AM)Sunset (PM)
113.16:047:12
213.16:057:10
313.06:077:08
413.06:087:06
512.96:097:04
612.96:107:02
712.86:127:01
812.86:136:59
912.76:146:57
1012.66:166:54
1112.66:176:52
1212.56:186:50
1312.56:196:48
1412.46:216:46
1512.46:226:44
1612.36:236:42
1712.36:256:40
1812.26:266:38
1912.26:276:36
2012.16:286:34
2112.06:306:32
2212.06:316:30
2311.96:326:28
2411.96:346:26
2511.86:356:24
2611.86:366:22
2711.76:386:20
2811.76:396:18
2911.66:406:16
3011.56:416:14

Solar energy in September

Daily solar energy (kWh/m²)

Average shortwave solar energy reaching the ground each day in September, about 4.1 kWh/m².

For context, solar energy here swings from a low near 1.15 kWh/m² to a high of 6.61 kWh/m² in June across the year — September's 4.1 kWh/m² falls in the middle.

024151015202530
Solar energy (kWh/m²)Level
14.8Bright
24.8Bright
34.7Bright
44.7Bright
54.7Bright
64.6Bright
74.5Bright
84.5Bright
94.5Bright
104.4Bright
114.3Bright
124.3Bright
134.2Bright
144.2Bright
154.1Bright
164.1Bright
174.0Bright
184.0Moderate
193.9Moderate
203.9Moderate
213.8Moderate
223.8Moderate
233.7Moderate
243.6Moderate
253.6Moderate
263.5Moderate
273.5Moderate
283.4Moderate
293.4Moderate
303.3Moderate
Planning a trip in September

Is September a good time to visit Mackinac Island?

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

5.9
Sightseeing
4th-best month of the year
2.6
Beach & pool
4th-best month of the year

September is a reasonable time to visit Mackinac Island for sightseeing.

What to pack for Mackinac Island in September

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

In September, Mackinac Island sees daytime highs around 66°F and nights near 55°F. Worth packing: rain gear. About 11 days see rain.

rain gear

Sea temperature near Mackinac Island in September

The nearest coast averages about 61°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 66°F and coldest in February near 34°F.

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

30°40°50°60°70°JanFebMarAprMayJunJulAugSepOctNovDecbracingcoolrefreshing
Sea temperature (°F)Comfort
Jan35Bracing
Feb34Bracing
Mar34Bracing
Apr36Bracing
May41Bracing
Jun52Bracing
Jul62Cool
Aug66Cool
Sep61Cool
Oct53Bracing
Nov44Bracing
Dec38Bracing

UV index in Mackinac Island 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 Mackinac Island peaks around June 19 at about 8 (very high) — sunscreen, a hat and midday shade are essential. It bottoms out near January 1 at about 1 (low).

The index reaches 3 or more — the level where the WHO recommends sun protection — in 7 months of the year.

025710JanFebMarAprMayJunJulAugSepOctNovDecLowModerateHighVery highHighModerateLowJun 19UV 8Jan 1UV 1
UV index (midday)Level
Jan1Low
Feb2Low
Mar3Moderate
Apr5Moderate
May7High
Jun8Very high
Jul8Very high
Aug7High
Sep5Moderate
Oct3Moderate
Nov2Low
Dec1Low
Location & terrain

Where is Mackinac Island?

Mackinac Island sits at 45.8°N, 84.6°W, 0 ft above sea level, in United States. The nearest listed city is Sault Ste. Marie, 47 mi away.

Topography around Mackinac Island

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

Within 2 miles, the terrain around Mackinac Island has only modest variations in elevation — a maximum elevation change of 351 ft around an average of 614 ft above sea level; within 10 miles, only modest variations in elevation — a maximum elevation change of 351 ft; within 50 miles, significant variations in elevation — a maximum elevation change of 1,037 ft.

The land around Mackinac Island is covered by water (72%) and trees (24%) within 2 miles, water (75%) and trees (22%) within 10 miles, and trees (48%) and water (44%) within 50 miles.

2 miles
351 ft
10 miles
351 ft
50 miles
1,037 ft
treesgrasslandcroplandartificial surfaceswater
September weather nearby: Sault Ste. Marie 47 mi · Sault Ste. Marie 48 mi · Traverse City 89 mi · Marquette 141 mi · Midland 155 mi · Mount Pleasant 156 mi · Bay City 160 mi · Saginaw Township North 168 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 Mackinac Island (45.8492°, -84.6189°, 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. 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).