Lake Michigan is the second-largest of the Great Lakes by volume and the third-largest by surface area after Lake Superior and Lake Huron. Area wise it is larger than the states of Massachusetts, Connecticut, and New Jersey combined.
It is also the only one of the Great Lakes located entirely within the territory of the United States. It is bordered by the states of Wisconsin, Illinois, Indiana, and Michigan.
Lake Michigan is conjoined with Lake Huron through the narrow Straits of Mackinac, giving it the same surface elevation (577.5 feet / 176 m ASL) as its easterly counterpart. Technically, Lake Michigan and Lake Huron are a single lake (Mich-uron or Hur-igan?). If Lake Michigan and Lake Huron were actually treated as a single lake, it would be the largest freshwater lake in the world by surface area.
The primary water sources for Lake Michigan are the Fox River, the Grand River, and the Menominee River. A few others also contribute to a lesser degree. Additionally, waters from Lake Huron, while rare, occasionally flow into Lake Michigan through the Straits of Mackinac.
The lake's three major outlets are the Straits of Mackinac where it flows eastward via the lower lakes, to the Atlantic Ocean and the Chicago and Calumet rivers where it flows southward to the Gulf of Mexico.
Lake Michigan Facts
Lake Michigan is ≈266.8 NM (307 SM / 494 KM) long and 102.5 NM (118 SM / 189.9 KM) wide at its widest point.
While Lake Michigan has no direct navigational access to the Atlantic Ocean or the Gulf of Mexico, it is connected by a number of rivers, lakes, and waterways. The routes chosen will be primarily determined by your vessels draft and masthead height.
For deep draft vessels, the only option is the Atlantic Ocean. The route is via the St. Lawrence River, Lake Ontario, the Welland Canal, Lake Erie, and Lake Huron. The limiting vertical clearance for this route is restricted to 116.5 feet.
On the other hand, for shallow draft vessels a number of options present themselves.
The limiting vertical clearance for the Atlantic Ocean shallow draft routes is: 17’ 0.0" on the Champlain Canal, 15’ 7.44" on the western end of the Erie Canal, and 21’ 1.8" on the Oswego Canal. All clearances are measured at "Normal Pool Levels."
There is basically two routes that can be taken, but both routes require the use of the Chicago River/Sanitary Canal, Calumet River, Des Plaines River, the Illinois River, and Mississippi River to the confluence with the Ohio River. From there you can opt to continue south on the Mississippi to New Orleans and the Gulf, or make use of the Ohio River, Tennessee River, and the Tombigbee to Mobile, AL and out to the Gulf.
Regardless of the route chosen, the limiting vertical clearance to the Gulf of Mexico is hampered by a 19 foot vertical clearance restriction.
For all vessels the navigation season is governed by ice on the lake. For commercial vessels and lock operations, the navigation season typically begins in late March (20th to the 31st) and runs through late December (24th to the 31st) typically being closed January, February, and a large portion of March.
For most recreational boaters, they typically launch in May and haul out by late October or early November.
Because of its depth, Lake Michigan has never completely frozen over. It has on sever winters reached 90% +, but due to wind, waves, and the huge amount of heat stored in the lakes waters, 100% has never happened at least back to the mid 1800's.
Buoys and beacons on Lake Michigan make use of the standard IALA Region B lateral buoyage system (Red Right Returning). In the Great Lakes, "Red Right Returning" is generally considered to be upbound from the St. Lawrence River to Duluth, MN on Lake Superior. Southbound on Lake Michigan is also considered to be upbound.
Lake Michigan Facts
Lake Michigan has a shoreline length of 1,400 SM (2,300 KM). When its islands are included, the lake's shoreline increases to 1,640 SM (2,639 KM).
The following NOAA Charts provide full coverage of Lake Michigan's coastal waters from the Straits of Mackinac south along the west coast of Michigan then west towards Chicago before turning north along the east coast of Wisconsin, then east along Michigan's Upper Peninsula returning to the Straits of Mackinac: #14901, #14881, #14911, #14912, 14913, #14907, #14906, #14905, #14904, #14910, #14909, and #14908.
Chart #14901 – Provides limited detail for the entirety of Lake Michigan.
Chart #14881 – De Tour Passage to Waugoshance Point - Covers the Straits of Mackinac and its Approaches.
Chart #14911 – Waugoshance Point to Seul Choix Point - Covers the coast line south to Beaver Island and west to Seul Choix Point.
Chart #14913 – Grand Traverse Bay to Little Traverse Bay - Covers from Harbor Springs, Mi south to Leelanau Peninsula, MI.
Chart #14912 – Platte Bay to Leland - Covers the coast from Leland, MI to Platte River Point, MI including the Manitou Passage
Chart #14907 – Stony Lake to Point Betsie - Covers from Platte River Point, MI south to Stony Lake, MI.
Chart #14906 – South Haven to Stony Lake - Covers from Stony Lake, MI south to South Haven, MI.
Chart #14905 – Waukegan to South Haven - Covers from South Haven, MI south and west to Waukegan, IL.
Chart #14904 – Port Washington to Waukegan - Covers from Waukegan, IL north to Port Washington, WI
Chart #14903 – Algoma to Sheboygan - Covers from Harrington Beach, WI north to Algoma, WI.
Chart #14910 – Lower Green Bay Algoma and Oconto - Covers from Kewaunee, WI north including the lower parts of Green Bay, WI.
Chart #14909 – Upper Green Bay - Covers from Marinette, WI north to Summer Island, MI.
Chart #14908 – Dutch Jones Point to Fishery Point - Covers from Fishery Point, MI north and east to Dutch Johns Point, MI.
The following electronic charts provide detailed coverage of all the Great Lakes from Montreal, CA on the St. Lawrence River to Duluth, MN on Lake Superior including: Green Bay, Saginaw Bay, Georgian Bay, Lac Nipissing, Lake St. Clair, Lake Simcoe, Seneca Lake, Cayuga Lake, Oneida Lake, Trent-Severn Waterway, Thousand Islands, the St. Lawrence River from Kingston to Montreal, the Ottawa River from the St. Lawrence River to Ottawa, Mohawk River, Rideau River, Welland Canal and Erie Canal.
Digital - Bluechart G2 Vision microSD™/SD™ card: VUS042R-Great Lakes
C-Map Max Chart NA-M026: Great Lakes, North East Coast & Appr. – All of the Great Lakes
Navionics Platinum+ 901P+: East Great Lakes – Ontario, Erie, and Huron
Navionics Platinum+ 900P+: West Great Lakes – Huron, Michigan, and Superior
Lake Michigan is the second deepest of the (5) Great Lakes with the deepest section of the lake being in the Chippewa Basin.
Other than the northern end of the lake and Green Bay, the 5 fathom line (30 feet / 9.1 meters) can generally be found (1) NM offshore or less.
Lake Michigan Facts
Average depth of the lake is 279 feet (46.5 fathoms or 85 meters). The deepest point being 923 feet (153.8 fathoms or 281 meters) located near 44°28’28" N / 86°42’34" W. Approximately 20.9. NM (24.1 SM / 38.7 KM) northwest of Manistee, MI's North Pierhead Light.
Below is a list of Lake Michigan coast lights with a range equal to or greater than 10 SM. From the Straits of Mackinac west then south along the western shore of Michigan, turning west along shoreline of Indiana and Illinois, then north along the east shore of Wisconsin, and finally east along the shore of Michigan's Upper Peninsula:
White Shoal Light
Fl 5s 125ft 11 SM/9.6 NM/17.7 KM HORN RACON (—·—)
Beaver Island Light
Iso R 6s 51ft 11 SM/9.6 NM/17.7 KM
Grand Traverse Light
Fl 6s 50ft 14 SM/12.2 NM/22.5 KM
Point Betsie Light
Fl 10s 52ft 19 SM/16.5 NM/30.6 KM
Manistee N. Pierhead Light
Fl G 6s 55ft 12 SM/10.4 NM/19.3 KM
Grand Haven Light
Fl R 10s 42ft 15 SM/13.0 NM/24.1 KM
Benton Harbor N. Pierhead Light
Iso 6s 31ft 13 SM/11.3 NM/20.9 KM HORN
Indiana Harbor Light
Iso G 6s 78ft 12 SM/10.4 NM/19.3 KM
Waukegan Harbor Light
Oc G 4s 36ft 12 SM/10.4 NM/19.3 KM
Wind Point Light
Fl 20s 111ft 21 SM/18.2 NM/33.8 KM
Manitowoc Harbor Light
Iso 6s 52ft 12 SM/10.4 NM/19.3 KM
Rawley Point Light
Fl 15s 113ft 21 SM/18.2 NM/33.8 KM
Sturgeon Bay Canal Light
Fl R 10s 107ft 17 SM/14.8 NM/27.4 KM
Detroit Harbor Light
Fl R 10s 107ft 11 SM/9.6 NM/17.7 KM HORN (MRASS)
Seul Choix Point Light
Fl 6s 80ft 16 SM/13.9 NM/25.7 KM
Grays Reef Light
Fl R 10s 57ft 14 SM/12.2 NM/22.5 KM HORN RACON (——·)
Ile Aux Galets Light
Fl 6s 58ft 11 SM/9.6 NM/17.7 KM
N. Manitou Shoal Light
Fl R 15s 79ft 14 SM/12.2 NM/22.5 KM HORN RACON (—·)
Frankfort N. Breakwater Light
F 72ft 16 SM/13.9 NM/25.7 KM
Muskegon Harbor Light
Fl R 4s 50ft 10 SM/8.7 NM/16.1 KM
South Haven S. Pierhead Light
F R 37ft 13 SM/11.3 NM/20.9 KM HORN (MRASS)
Michigan City Light
Fl R 10s 55ft 15 SM/13.0 NM/24.1 KM HORN (MRASS)
Fl R 5s 82ft 15 SM/13.0 NM/24.1 KM HORN
Racine Reef Light
Fl 6s 50ft 11 SM/9.6 NM/17.7 KM HORN
Milwaukee Breakwater Light
Fl R (2) 10s 61ft 15 SM/13.0 NM/24.1 KM HORN (MRASS)
Two River Harbor Light
Fl R 2.5s 34ft 12 SM/10.4 NM/19.3 KM
Algoma Harbor Light
Iso R 6s 48ft 12 SM/10.4 NM/19.3 KM HORN (MRASS)
Cana Island Light
F 83ft 17 SM/14.8 NM/27.4 KM
St. Martin Island Light
Fl 10s 84ft 16 SM/13.9 NM/25.7 KM
Lansing Shoals Light
Fl 10s 69ft 12 SM/10.4 NM/19.3 KM HORN RACON (—·——)
Distances between major points on Lake Michigan are listed below. The distances table is useful in planning overnight stops while transiting the lake and is available for download.
|Lake Michigan Distance Table (SM)|
|Mackinaw Point, MI||Charlevoix, MI||Traverse City, MI||Muskegon, MI||Holland, MI||Michigan City, IN||Chicago, IL||Racine, WI||Milwaukee, WI||Sheboygan, WI||Sturgeon Bay, WI||Green Bay, WI|
|Mackinaw Point, MI||0.0||56.0||97.0||224.0||257.0||325.0||324.0||272.0||250.0||212.0||155.0||198.0|
|Traverse City, MI||97.0||45.0||0.0||195.0||227.0||295.0||293.0||242.0||228.0||182.0||131.0||178.0|
|Michigan City, IN||325.0||278.0||295.0||108.0||82.0||0.0||38.0||84.0||104.0||146.0||217.0||264.0|
|Sturgeon Bay, WI||155.0||113.0||131.0||124.0||155.0||217.0||208.0||150.0||133.0||81.0||0.0||47.0|
|Green Bay, WI||198.0||160.0||178.0||171.0||202.0||264.0||255.0||197.0||180.0||128.0||47.0||0.0|
|Distances shown above are in Statute Miles and are rounded to the nearest whole mile.|
The above table can be downloaded for your use. The Lake Michigan distance table contains the tables in Statute Miles, Nautical Miles, and Kilometers. The files are Zipped Adobe (.pdf) format.
The speed limits on the open waters of Lake Michigan can generally be considered to be unlimited except where posted or common sense prevails.
As a general guide, the Straits of Mackinac to Chicago, IL (281.5 NM) could be done in a little over 9.3 hours at 30 knots.
More realistically, with a SOG of 15 knots you will probably require about 18.8 hours; 28.2 Hours at 10 knots, and 35.2 to 40.2 hours at typical trawler and sailboat speeds.
Studies show that the Great Lakes do in fact experience a semidiurnal tidal pattern. The tidal range however, is extremely small - averaging around 1 inch and reaching 1.6 to 2.0 inches (4-5cm) during the largest of tides. This tidal range is so small, that they are often hidden by other fluctuations in water levels that are caused by the weather. As a result, the Great Lakes are generally considered to be "non-tidal."
The normal elevation of the lake's surface does in fact change. During the course of each year, Lake Michigan’s surface is subject to a consistent seasonal rise and fall, the lowest stages prevailing during the winter and the highest during the summer. These fluctuations generally average around 3.0 feet. Recently however it appears that lake levels are getting higher.
In addition to seasonal fluctuations, Seiches (changes in water level produced by winds, storms, squalls, and to a lesser degree, barometric pressure changes) often occur. The wind and barometric pressure changes that accompany squalls can produce fluctuations lasting from a few minutes to a few hours. Strong storm winds of sustained speed and direction can produce fluctuations lasting a few hours or a day. Lake Michigan is less prone to these water surface oscillations than Lake Erie due to the lake's surface area, north/south orientation, and deeper depths.
Lake Michigan's surface currents are typically wind driven and tend to follow the wind direction. This implies that surface current tends to flow from the southwest to the northeast since the predominant wind direction on the lake is southwesterly.
Rarely do surface current speeds on Lake Michigan exceed 0.5 knot.
Lake Michigan Facts
Lake Michigan’s has a fresh water volume of 1,180 SM3 (4,918 KM3), that works out to 1 Quadrillion, with a "Q," gallons of water or (1.299*1015 gallons to be more precise).
Like all of the individual Great Lakes, Lake Michigan acts like heat sink that moderates the temperatures of the surrounding land, cooling the summers and warming the winters. The lake also acts like giant humidifier, increasing the moisture content of the air. In the winter, this moisture contributes to heavy snowfalls.
The weather on Lake Michigan averages from cool to mild during the months of May thru October.
Winds with southerly components are prevalent during the entire navigation season. Northerlies are a little less frequent but are common particularly in spring.
Air temperatures range from low to mid 60's in May to upper 70's during July and August before dropping back to the mid 50's in October.
Water temperatures average between 39° F in May peaking at approximately 69° F Late July and early August before dropping back into the mid 40's by the end of October.
Spring winds can still blow strong, with winds of 28 knots or more encountered about 4 to 8 percent of the time. They do slacken from their winter fierceness, with southerlies and south-westerlies becoming more frequent and northerlies less so as summer approaches.
Strong winds are infrequent in summer and mostly associated with thunderstorms. South and southwest winds prevail particularly in the north; south-easterlies are also common in the south.
Coastal winds are more localized and variable. Along the Michigan shore, spring winds are variable, particularly in the morning, when northerlies, easterlies and southerlies are among the most common. By afternoon, aided by a lake-breeze effect, there are a preponderance of winds out of the south, particularly with the approach of summer. Summer also brings a slackening of wind speeds. The likelihood of encountering winds of 28 knots or more falls from a 4- to 10-percent chance in March to less than 3 percent by May.
The most likely cause of strong winds in spring and summer are thunderstorm gusts. By summer, wind speeds of 28 knots or more occur less than 4 percent of the time and less than 2 percent most of the time. Summer winds along the shore are usually out of the east through south during the morning hours, swinging to the south and northwest by afternoon, with an increase in speed.
By October, there is a noticeable increase in wind speeds. Speeds of 28 knots or more increase to 4 to 6 percent. By December, these speeds can be encountered up to 11 percent of the time. Morning directions are variable, with east, south and west winds among the most common. Afternoon winds are most often out of the south through west. The strong winds continue throughout the winter and are associated with winter storms, which bring a variety of winds from southwest through northeast.
Along the west shore of the lake, spring winds are variable, but the influence of the land-lake breeze is already noticeable. Morning winds often have a westerly component, while an easterly influence is evident during the afternoon.
Wind strength gradually abates during spring; by May, winds of 28 knots or more are encountered less than 1 percent of the time.
Summer winds rarely exceed 28 knots through September. Morning breezes are generally out of the south through west. During the day, they strengthen slightly and blow out of the northeast through southeast; southwest and west winds are also common during the afternoon, when the prevailing circulation interferes with the lake-breeze effect.
With autumn comes an increase in strength and less diurnal variability. By November, winds of 28 knots or more are encountered about 1 percent of the time. Fall winds blow mainly out of the south through northwest, with southwest and west winds the most frequent.
Gales are most likely from September through April, particularly in the fall. During this season gales blow 3 to 7 percent of the time; speeds of 28 knots or more occur from 12 to 20 percent of the time. Strong winds often blow out of the west and northwest, making east shore harbor entrances dangerous.
The strongest wind measured over-the-lake was out of the west-southwest at 58 knots. However, since Green Bay recorded a 70-knot southwesterly gust in May 1989, it is not unrealistic to expect a wind extreme of 70 knots or more over open waters.
Rough seas are created when strong winds blow over a long fetch of water. The orientation of Lake Michigan make it susceptible to winds out of the northerly and southerly quadrants, which can quickly raise dangerous seas.
Northerly winds cause this on the southern part of the Lake Michigan and southerly winds have the same effect on the northern part of the lake. They can raise dangerous seas and generate hazardous currents at harbor entrances.
Winds with southerly components are prevalent during the entire navigation season. Northerlies are a little less frequent but are common particularly in spring. The sea conditions are worst in October and November, when, lake wide, wave heights of 5 to 10 feet (2 to 3 m) are encountered about 35 percent of the time. In October, south through southwest winds are most often responsible, while by November west through north winds often generate rough seas.
Seas of 10 feet (3 m) or more are encountered 3 to 5 percent of the time from November through March. Extreme waves of 20 to 22 feet (6 to 7 m) have been encountered. During the spring, high seas are infrequent, but 5- to 10-foot (2 to 3 m) seas develop 15 to 30 percent of the time in the south and 20 to 40 percent in the north.
Since strong winds over a long fetch of water are conducive to creating rough seas, strong winds out of the N and S quadrants over Lake Michigan are often danger signals.
Summer seas climb above 10 feet (3 m) less than 1 percent of the time, while those in the 5- to 10-foot (2 to 3 m) category drop to less than 20 percent in June and July. By August, the fall buildup begins.
While thunderstorms can occur at any time, they are most likely from May through September. During this period, thunder is heard on an average of 4 to 8 days per month at locations along the shore and 1 to 3 percent of the time over open water.
Activity is a little more frequent in the south than the north. Over open water, July and August are the peak months, while June and July are more active along the shore.
During the summer, a cool dome of air, the result of the lake breeze, often blocks thunderstorms and squall lines during the day. This results in a nighttime peak in activity. However, a severe squall line may break through this block, or due to a strong prevailing circulation, the block may not exist.
In spring, when there is often a clash between cold and warm air, thunderstorms and squall lines can be violent. On occasion they may trigger tornadoes or even waterspouts. This area lies at the northeast edge of the nation's maximum frequency belt for tornadoes. Although rare, tornadoes are most likely from April through June.
Poor visibilities caused by fog is the principal cause of visibilities less than 0.5 statute mile (0.4 nm). It is most likely in the spring and early summer over open water (advection fog) and from late fall through spring along the shore (radiation fog).
In open waters, from March in the south and April in the north through June, warm moist air riding winds with a southerly component blowing at 5 to 20 knots reduces visibilities to less than 0.5 statute mile (0.4 nm) from 5 to 10 percent of the time. These fogs are most likely during the morning and early afternoon and when the air is 5° to 15°F (3° to 8°C) warmer than the water. May and June are the most likely months.
The shores of Lake Michigan are subject to varying amounts of fog. Upwelling along the northwest shores increases the possibility of advection fog in spring and summer; in fact, the west shore waters in general are 5 to 10°F (3° to 6°C) cooler than the east shore waters.
North of Chicago, visibilities drop to less than 0.5 statute mile (0.4 nm) on about 25 to 35 days annually. In the Chicago area, smoke and haze frequently reduce visibility to the 3- to 6-mile (2.6 to 5.2 nm) range, but dense fog is less common than it is to the north. It is most likely from fall through late spring with a minimum in July.
Along the Michigan shore, the indication from the few locations with fog observations is that frequencies are similar to those along the Wisconsin shore. In comparing Muskegon to Milwaukee, both exhibit a morning maximum from April through October, early morning in the summer and around sunrise in other seasons. The most fog-free times occur during the afternoon in spring and late morning through evening in summer. Milwaukee is more fog prone in spring, but less in summer and fall. Overall, Muskegon averages 5 fewer days annually with visibilities less than 0.5 statute mile (0.4 nm).
Though Lake Michigan has never frozen over completely, it came close during the winter of 1993 to 1994 when ice reached 95 percent coverage.
The first waters to form an extensive ice cover are Green Bay and the Bays de Noc, located in the northwestern corner of the lake. The Straits of Mackinac and the shallow areas north of Beaver Island usually follow. The Straits are usually closed by mid-December.
In a normal winter, an early ice cover is established by the end of January and includes the above-mentioned waters plus the extreme southern part of the lake.
|Meteorological Table – Lake Michigan|
|May thru October Average Occurances|
|Wind > 33 Kts||0.8%||0.3%||0.3%||0.5%||1.6%||3.8%||2.2%|
|Seas > 9’||0.6%||0.2%||0.2%||0.4%||1.2%||2.5%||1.4%|
|Visibility < 2 NM||11.0%||11.4%||5.7%||4.2%||2.8%||2.0%||6.1%|
|Temps > 69° F||0.4%||4.2%||21.5%||30.3%||8.0%||0.3%||7.1%|
|Mean Temps °F||46.6°||55.8°||65.5°||67.4°||60.9°||50.0°||50.2°|
|Temps < 33° F||1.0%||0.2%||0.1%||0.1%||0.0%||1.0%||11.3%|
|Wind Speeds ≤ 15 Knots||80.3%||83.5%||87.3%||87.6%||75.4%||62.4%|
|Wind Speeds ≤ 10 Knots||50.9%||55.6%||60.8%||64.1%||52.7%||39.9%|
National Weather Service (NOAA Weather Radio) - Stations provide mariners with VHF-FM broadcasts of weather warnings, forecasts, radar reports and surface weather observations. Reception range is up to 40 miles from the antenna site, depending on the terrain, type of receiver and antenna used.
|Lake Michigan - NOAA Weather Radio|
|WNG-572||Emmet County, MI||162.475 MHz||WX-3|
|KIH-22||Traverse City, MI||162.400 MHz||WX-2|
|WNG-672||Wolf Lake, MI||162.425 MHz||WX-4|
|WWF-36||Hesperia, MI||162.475 MHz||WX-3|
|WXN-99||West Olive, MI||162.425 MHz||WX-4|
|WXJ-57||South Bend, IN||162.400 MHz||WX-2|
|KWO-39||Chicago, IL||162.550 MHz||WX-1|
|KZZ-76||Rancine, WI||162.450 MHz||WX-5|
|KEC-60||Milwaukee, WI||162.400 MHz||WX-2|
|WWG-91||Sheboygan, WI||162.525 MHz||WX-7|
|KIG-65||Green Bay, WI||162.550 MHz||WX-1|
|WXN-69||Sister Bay, WI||162.425 MHz||WX-4|