St Ignace Mackinac Bridge, Michigan climate: Climate normals at a NOAA weather station
St Ignace Mackinac Bridge's normal year runs from 14°F January nights to 75°F July afternoons. (NOAA 1991-2020 normals)
In metric: a yearly mean of 6.8°C, January lows of −10°C, July highs of 24°C.
- NOAA stationSt Ignace Mackinac Bridge
- Station IDUSC00207274
- Location45.85°N 84.72°W
- Elevation595 ft (181 m)
On October 23, the normal high in St Ignace Mackinac Bridge is 52°F and the normal low 39°F.
Normals describe a typical year at the station, not a forecast. The National Weather Service forecast for St Ignace Mackinac Bridge.
- Jan 26° 14°
- Feb 29° 14°
- Mar 37° 20°
- Apr 48° 31°
- May 61° 42°
- Jun 71° 52°
- Jul 75° 59°
- Aug 75° 59°
- Sep 69° 53°
- Oct 56° 42°
- Nov 43° 32°
- Dec 33° 23°
Each month: normal high (large) and low, °F. Fill: the month's normal mean, colder blue to hotter red.
What is the weather like at St Ignace Mackinac Bridge each month?
July is the warmest month, with normal highs of 75°F; January the coldest, with normal lows of 14°F.
| Month | High | Low | Mean | Wet days | 90°F days | Freezing nights | Daylight |
|---|---|---|---|---|---|---|---|
| January | 26°F | 14°F | 19.9°F | – | <1 | 30 | 9 h |
| February | 29°F | 14°F | 21.1°F | – | <1 | 27 | 10 h 20 min |
| March | 37°F | 20°F | 28.2°F | – | <1 | 28 | 11 h 50 min |
| April | 48°F | 31°F | 39.6°F | – | <1 | 15 | 13 h 30 min |
| May | 61°F | 42°F | 51.4°F | – | <1 | 2 | 14 h 50 min |
| June | 71°F | 52°F | 61.5°F | – | <1 | <1 | 15 h 40 min |
| July | 75°F | 59°F | 67.2°F | – | <1 | <1 | 15 h 20 min |
| August | 75°F | 59°F | 67.1°F | – | <1 | <1 | 14 h 10 min |
| September | 69°F | 53°F | 61.1°F | – | <1 | <1 | 12 h 40 min |
| October | 56°F | 42°F | 48.9°F | – | <1 | 4 | 11 h |
| November | 43°F | 32°F | 37.2°F | – | <1 | 16 | 9 h 30 min |
| December | 33°F | 23°F | 27.8°F | – | <1 | 27 | 8 h 40 min |
| Year (annual) | 52°F | 37°F | 44.2°F | – | <1 | 149 |
The same normals in °C and millimetres
| Month | High | Low | Mean |
|---|---|---|---|
| January | −3°C | −10°C | −6.7°C |
| February | −2°C | −10°C | −6.1°C |
| March | 3°C | −7°C | −2.1°C |
| April | 9°C | 0°C | 4.2°C |
| May | 16°C | 5°C | 10.8°C |
| June | 21°C | 11°C | 16.4°C |
| July | 24°C | 15°C | 19.6°C |
| August | 24°C | 15°C | 19.5°C |
| September | 21°C | 12°C | 16.2°C |
| October | 13°C | 6°C | 9.4°C |
| November | 6°C | 0°C | 2.9°C |
| December | 0°C | −5°C | −2.3°C |
NOAA publishes no 1991-2020 snowfall normal for this station. The nearest record that keeps one, Moran (11 miles away), gets 81 inches of snow in a normal year; elevation and distance can change that.
Source: NOAA NCEI 1991-2020 monthly normals, station USC00207274; annual normals. Wet days: 0.01 inch or more; 90°F days and freezing nights: NOAA's day counts. Daylight: sunrise to sunset on the 15th, computed from the latitude.
Which months are mildest at St Ignace Mackinac Bridge?
Normal highs sit between 65°F and 85°F in June, July, August and September.
That is a measurement, not a recommendation: it counts the months whose normal afternoon high sits between 65°F and 85°F, where a light layer is enough by day.
Source: NOAA NCEI 1991-2020 monthly normals, station USC00207274.
When is the last frost at St Ignace Mackinac Bridge?
In St Ignace Mackinac Bridge, the last spring frost (32°F) comes after May 7 in half of years and after May 22 in one year in ten; the first autumn frost comes before October 23 in half of years and before October 6 in one year in ten.
Frost-free in half of yearsFrost in 1 to 9 years out of 10Frost most years
- Last spring frost, half of years after
- May 71 year in 10 after May 22; 9 in 10 after April 25
- First autumn frost, half of years before
- October 231 year in 10 before October 6; 9 in 10 before November 6
NOAA puts the median frost-free season at 167 days, and the season without a hard freeze (28°F) at 191 days.
A hard freeze (28°F) comes after April 25 in half of springs and before November 3 in half of autumns.
The USDA's 2023 Plant Hardiness Zone Map puts St Ignace Mackinac Bridge in zone 5b in ZIP code 49757, the nearest ZIP area. By the map's own method, the average of each year's coldest night over 1991-2020, the station is in zone 6a: the coldest night of a typical year reaches −9°F (17 complete years); the map interpolates between stations and terrain, so the station and the ZIP area can differ by half a zone.
Frost dates for every NOAA station in Michigan · Frost dates by ZIP code
Source: NOAA NCEI 1991-2020 annual normals (frost probabilities), station USC00207274; USDA 2023 Plant Hardiness Zone Map, ZIP listings: PRISM Group, Oregon State University, https://prism.oregonstate.edu, accessed October 8, 2026; the station zone: ACIS daily lows, 1991-2020. A 10% date means one year in ten has a frost after it in spring or before it in autumn.
How hot and how cold does it get at St Ignace Mackinac Bridge?
In a normal year in St Ignace Mackinac Bridge, a 90°F day is rare and 149 nights fall to 32°F or colder.
- Days at 90°F or more
- fewer than 1a normal year
- Days at 100°F or more
- fewer than 1a normal year
- Nights at 32°F or colder
- 149a normal year
- Days that stay below freezing
- 70high of 32°F or less
Source: NOAA NCEI 1991-2020 annual normals, station USC00207274.
How sunny is it at St Ignace Mackinac Bridge?
Over a year 69% of the sunlight that would reach the ground under clear skies gets through the clouds at St Ignace Mackinac Bridge, 3.5 kWh per square metre a day. July is the sunniest month (79%) and December the cloudiest (48%).
| Month | Share of clear-sky sunshine | Sunshine, kWh/m² a day |
|---|---|---|
| January | 51% | 1.2 |
| February | 58% | 2.0 |
| March | 67% | 3.4 |
| April | 68% | 4.6 |
| May | 71% | 5.5 |
| June | 74% | 6.1 |
| July | 79% | 6.1 |
| August | 78% | 5.2 |
| September | 74% | 3.9 |
| October | 61% | 2.3 |
| November | 53% | 1.3 |
| December | 48% | 0.9 |
Source: NASA POWER solar climatology, 2001-2020 (CERES SYN1deg). Satellite-based, for the 1-degree cell (about 100 km across) around the station, so it describes the area rather than the airport.
How many heating and cooling degree days does St Ignace Mackinac Bridge record?
A normal year at St Ignace Mackinac Bridge brings 7,796 heating degree days, 45% more than the median U.S. place (5,373), and 268 cooling degree days, 71% fewer than the median (908). Eight months need 300 or more heating degree days, a monthly mean of about 55°F or colder. For gardens and crops, NOAA counts 1,941 growing degree days a year above 50°F.
| Month | Heating | Cooling |
|---|---|---|
| January | 1,398 | 0 |
| February | 1,229 | 0 |
| March | 1,141 | 0 |
| April | 762 | 0 |
| May | 425 | 1 |
| June | 138 | 33 |
| July | 34 | 101 |
| August | 32 | 97 |
| September | 151 | 34 |
| October | 502 | 2 |
| November | 833 | 0 |
| December | 1,153 | 0 |
| Year (annual) | 7,796 | 268 |
Source: NOAA NCEI 1991-2020 monthly normals, station USC00207274. A degree day is one degree of a day's mean temperature below 65°F (heating) or above it (cooling); utilities use them to estimate energy use.
How does St Ignace Mackinac Bridge's climate compare?
St Ignace Mackinac Bridge is warmer than 35 of the 140 places with their own NOAA record in Michigan. Across the 7,247 U.S. stations with normals, its annual mean of 44.2°F is warmer than 16%.
Source: NOAA NCEI 1991-2020 normals for every station PlainClimate covers.
Which places near St Ignace Mackinac Bridge share this climate record?
Mackinaw City has no NOAA station with 1991-2020 normals of its own, and this station is the nearest full record. A place's own climate can differ from these figures, by several degrees where it sits much higher or lower than the station, nearer the coast, or inside a large city's heat; for the larger places the next nearest records are named with their yearly mean, so the spread around them is visible, and places of 50,000 or more have their own page with NOAA's gridded normals.
- Mackinaw City, MI840 people · 5 mi S
Source: Census Bureau 2024 Gazetteer (place centers) and Vintage 2024 population estimates. Distance and direction from the station to each place's center.
Questions about St Ignace Mackinac Bridge's climate
What is the coldest month at St Ignace Mackinac Bridge?
January, with a normal high of 26°F and a normal low of 14°F. The warmest is July (75°F by day, 59°F at night).
Does it snow at St Ignace Mackinac Bridge?
Yes. NOAA publishes no 1991-2020 snowfall normal for the station; the nearest record that keeps one, Moran (11 miles away), records 81 inches of snow in a normal year.
What plant hardiness zone is St Ignace Mackinac Bridge in?
The USDA's 2023 map puts St Ignace Mackinac Bridge in zone 5b in ZIP code 49757, the nearest ZIP area. By the same method at the station, the coldest night of a typical year reaches −9°F (17 years, 1991-2020): zone 6a.
How late can frost come at St Ignace Mackinac Bridge?
In half of years the last 32°F night comes after May 7; in one year in ten it comes after May 22. Waiting until May 22 leaves about a one-in-ten chance of a later frost.
Nearby and next
- Michigan climateThe statewide normals and every place in the state
- St. Ignace, MI1 miles from this station, 42.4°F a year
- Moran, MI11 miles from this station, 41.7°F a year
- Cheboygan, MI18 miles from this station, 43.7°F a year
- Pellston, MI20 miles from this station, 42.6°F a year
- Compare two placesMonth by month, side by side
Download these normals (CSV) · JSON · How these figures are made