• The tower of the Au Sable Light Station against a summer blue sky. Photo © Craig Blacklock

    Pictured Rocks

    National Lakeshore Michigan

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  • Winter road closures

    While the calendar may say it is spring, Mother Nature says it is still winter in the central Upper Peninsula. Most roads remain closed by snow. More »

Environmental Factors

This far-away photo of Miners Beach was taken from the trail to Miners Castle, through snow-covered trees.

Miners Beach through the trees

Lars Jensen photo

Pictured Rocks National Lakeshore is located approximately 46 degrees north latitude and 86 degrees west longitude. The coldest months average well below 0°C (32°F) and the warmer months about 22°C (70°F).

Lake Superior greatly ameliorates temperature extremes, slowing spring warming and the onset of winter. The average date of the last freezing temperature in spring is June 8, and the average first fall freeze is September 23; however, freezing can occur during any month. The freeze-free period, or growing season, averages 107 days annually.

The big lake's presence also increases precipitation in the park. Annual precipitation averages 79 cm (31 inches); annual snowfall is 320 cm (126 inches). Snow generally covers the ground from late November through late April.

The park is within the second-most cloudy region of the United States, characterized by an annual mean cloud cover of 70 percent. Much of the cloudiness occurs in autumn and winter and can be attributed to cooler air flowing over Lake Superior being warmed along the shore, rising and forming clouds. This condition also often results in rain, fog, and snow. Lake-effect snow is a common feature of this climate and occurs when air moving across the lake is significantly cooler than the warmer lake surface. Cold winds sweeping across long expanses of warmer lake water can pick up a great deal of water vapor, which freezes and is deposited on the leeward shores.

The prevailing wind is from the west, with average velocities ranging from 12 to 15 kilometers per hour (7 to 9 mph). High winds and storm conditions on Lake Superior are not uncommon. The highest recorded one-minute wind speed is 98 kilometers per hour (59 mph).

 
 

Did You Know?

Lyndon B. Johnson being sworn in as President of the U.S. by Chief Justice Earl Warren as Lady Bird Johnson and Hubert Humphrey look on.

Pictured Rocks National Lakeshore is America's first National Lakeshore, authorized on October 15, 1966. On the same day, President Lyndon B. Johnson also signed into law another piece of landmark legislation -- the National Historic Preservation Act. More...