Lake Superior is renowned for its cold temperatures, rough seas, fog, and sudden squalls. 1, 2. Station Data. Boaters and paddlers should monitor marine weather forecasts and be constantly alert to changing conditions.. Average daytime high temperatures range from 60 degrees Fahrenheit in May, to the upper 80s in mid-summer, to the mid-60s in September. Summer surface temperatures in the lake appeared to have increased by about 4.5 °F (2.5 °C) between 1979 and 2007, compared with an approximately 2.7 °F (1.5 °C) increase in the surrounding average air temperature. Monthly: 1981-2010 normals History: 2007-2019 Lake Superior's ice cover is diminishing. Lake Superior average water temperature this year (red) versus long-term average. Lake Superior's surface water temperature in summer has warmed twice as much as the air above it since 1980. Recent lake temperatures reported that Lake Michigan’s waters have an average temperature of 75 degrees Fahrenheit (24 degrees Celsius) with the temperatures cooler closer to the center of the lake. Temperatures close to the shore have been measured higher than 80 degrees Fahrenheit (27 degrees Celsius and higher). An average of 7.00°C | 44.60°F water temperatures is reached in Superior (Lake Superior) over the year. The warmest water temperature in Lake Superior in June is 10.3°C/50.5°F, and the coldest water temperature in June is 2.6°C/36.7°F. Monthly averages Duluth Longitude: -92.1936, Latitude: 46.8421 Average weather Duluth, MN - 55811. Per decade since 1980, surface water temperature in summer has increased about 2 °F (1 °C), while regional air temperature has increased 1 °F (0.5 °C). The western Lake Superior Buoys are maintained by the University of Minnesota Duluth Large Lakes Observatory, with funding from the Great Lakes Observing System. Average water temperature in Lake Superior in June is 4.5°C/40.1°F and therefore is not suitable for comfortable swimming. Temperature and precipitation statistics for selected towns in the Lake Superior Basin. In Superior, the average percentage of the sky covered by clouds experiences significant seasonal variation over the course of the year.. They operate during the ice-free months each year, and are typically deployed in … Whereas in February the lowest value is measured with about 1.10°C | 33.98°F. Lake Superior, the deepest lake with by far the highest volume of water, is not as warm as the other Great Lakes, but still is running over 6 degrees above average. At 18.20°C | 64.76°F, the average monthly water temperature reaches its highest value in the year in August. The average water temperature now is 76 degrees, with the long-term average water temperature at 70 for this date.