Due to its geographic location and proximity to Lake Superior, Pictured Rocks National Lakeshore is greatly impacted by environmental factors of weather and climate. The park is located approximately 46 degrees north latitude and 86 degrees west longitude. The coldest months average well below 32°F (0°C) and the warmer months about 70°F (22°C).
Lake Superior greatly ameliorates temperature extremes, slowing spring warming as well as 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. Ice on the lake can last until June.
The big lake's presence also increases precipitation in the park. Annual rain precipitation averages 31 inches (79 cm); annual snowfall is 126 inches (320 cm). 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).
Other environmental factors affecting Pictured Rocks include:
Soundscape / Noise