The climate of Minneapolis–Saint Paul refers to the long-term weather patterns and past weather events in the Minneapolis–Saint Paul metropolitan area, located in east central Minnesota. Minneapolis and Saint Paul, together called the Twin Cities, form the center of the 15th largest city area in the United States. With a population of 3.6 million people, the region includes about 60% of Minnesota’s total population. Because it is located in the northern and central parts of the United States, the Twin Cities have the lowest average temperature of any major city area in the nation. Winters are very cold, summers are warm and humid, snow is common during winter, and thunderstorms that bring heavy rain occur in spring, summer, and autumn. Even though winter is cold, the area receives more sunlight during mid-winter than many warmer regions in the country, including all of the Great Lakes states, the Pacific Northwest, parts of the South, and nearly all of the Northeast. Unless stated otherwise, the weather data below comes from Minneapolis/St. Paul International Airport, the official weather station for the Twin Cities. The data is based on the 1981–2010 period.
General climatology
The climate of the Twin Cities is classified as a hot-summer humid continental climate with no dry season (Köppen Dfa). A key feature of this climate in the United States is that weather can change quickly and unpredictably, with extreme temperatures sometimes occurring. For example, the Twin Cities recorded a high temperature of 108 °F (42 °C), even though it is nearly 1000 miles farther from the equator than many other places. In contrast, winter temperatures in the Twin Cities are colder than in any other major city in the continental United States and are similar to those in Anchorage, Alaska. The area also experiences droughts, floods, and frequent winds that are often above 10 miles per hour (16 km/h).
Because the Twin Cities are located in the center of North America, they experience some of the largest temperature changes in the United States. Average temperatures range from 15.6 °F (−9.1 °C) in January to 73.8 °F (23.2 °C) in July. Without natural barriers to block cold air from Canada, the Twin Cities are often affected by cold air masses during winter, which bring very low temperatures and sometimes strong winds. Summer temperatures in the Twin Cities are similar to those in nearby cities like Chicago, but winter temperatures in the Twin Cities are colder. For example, the Twin Cities’ average January temperature of 15.6 °F (−9.1 °C) is lower than Chicago’s 23.8 °F (−4.6 °C), even though the two cities are only 350 miles (563 km) apart. During summer, Minneapolis often has hot temperatures and high humidity from May to September.
Temperature records in the Twin Cities date back to October 1, 1872. The coldest temperature recorded was −41 °F (−41 °C) on January 21, 1888, while the hottest was 108 °F (42 °C) on July 14, 1936, during the Dust Bowl. The coldest daily maximum temperature was −20 °F (−29 °C), and the warmest daily minimum was 86 °F (30 °C). Monthly average temperatures have ranged from −3.4 °F (−19.7 °C) in January 1875 to 81.4 °F (27.4 °C) in July 1936. Annual average temperatures have ranged from 38.5 °F (3.6 °C) in 1875 to 50.8 °F (10.4 °C) in 1931 and 2012.
In recent years, the urban heat island effect has influenced temperatures in the Twin Cities. Concrete, asphalt, and tall buildings trap heat, making temperatures warmer, especially at night, compared to surrounding areas. For example, the average annual temperature at Minneapolis-St. Paul International Airport is 45.4 °F, which is warmer than the average temperatures in Rochester (43.4 °F) and Mankato (44.7 °F), both of which are farther south.
The Twin Cities experience many types of precipitation. Rain is most common in summer, while snow, hail, sleet, freezing rain, and sometimes rain occur in winter. Summer months (June, July, and August) account for nearly half of the annual rainfall, often from thunderstorms. Thunderstorms can occur from March to November, and on rare occasions, thunder and lightning may accompany snowstorms (called thundersnow). Some summer thunderstorms are severe, producing strong winds, large hail, and occasionally tornadoes. The Twin Cities have experienced major derecho events, such as the Late-May 1998 tornado outbreak and derecho that traveled from South Dakota to New York. Summer thunderstorms are fueled by high humidity, with dew points often reaching the 70s °F (21 °C) or even 80 °F (27 °C). The highest recorded dew point in Minneapolis was 82 °F (28 °C) on July 19, 2011.
Winter precipitation includes snow, which is the most common form, but freezing rain, hail, sleet, and sometimes rain can also occur. Large storms, such as Panhandle hooks, can bring heavy snow and blizzard conditions. The average annual snowfall in the Twin Cities is 45.3 inches (115.1 cm), with about 100 days per year having at least 1 inch (2.5 cm) of snow. The most snowfall recorded in one winter was 98.6 inches (250 cm) during 1983–1984, while the least was 14.2 inches (36.1 cm) during 1930–1931.
Weather events
The Twin Cities metropolitan area is located near the northern edge of Tornado Alley. Because of this, the region experiences tornadoes almost every year. The first tornado recorded in the Twin Cities metro area was in 1820 at Fort Snelling. A damaging tornado struck St. Paul in 1891.
The worst tornado event in the Twin Cities occurred on May 6, 1965. That day, six tornadoes touched down in several counties in and around the western and northern parts of the metro area. These tornadoes killed 13 people and injured over 600. Four of the tornadoes were rated F4, and two of them hit Fridley, Minnesota, about an hour apart. This event was important because it was the first time in Minnesota history that civil defense sirens were used to warn people about severe weather. Live coverage by Twin Cities media was also never done before. WCCO’s continuous weather reports are credited with helping people stay safe during the tornadoes.
In 1981, a tornado called the Har-Mar tornado touched down in Minneapolis and affected the northern suburbs, including killing a man near Lake Harriet. On July 18, 1986, a tornado struck Fridley. Video from a KARE 11 news helicopter was shown live on their 5:00 pm newscast. The aerial footage from that day was never done before and was studied closely.
On May 25, 2008, an EF3 tornado hit the town of Hugo during the Late-May 2008 tornado outbreak. The tornado damaged or destroyed several homes, causing about $25 million in damage.
Although derechos do not have as strong winds as tornadoes, they affect larger areas and can cause similar damage. The costliest severe weather event in Twin Cities history was a derecho that happened on May 15, 1998. Large hail and damaging winds caused most of the $1 billion in reported damages. Two weeks later, on May 30, another large derecho produced winds over 80 miles per hour (130 km/h) across much of the Twin Cities. These two events together caused $1.5 billion in damage and created the largest debris cleanup project in Minnesota history.
On November 11, 1940, the Armistice Day Blizzard affected all of southeast Minnesota, killing 60 people. The Twin Cities recorded 17 inches of snow, and temperatures dropped nearly 60 degrees in one day. The largest snowstorm to affect most of the Twin Cities area was the Halloween Blizzard from October 31 to November 2, 1991. The Twin Cities airport reported 28.4 inches (72 cm) of snow. The heaviest snow fell in a line from there northward to Duluth. Smaller amounts fell to the east and west of that line, but it was the largest early-season snowstorm for the region.
The largest flash flood in Twin Cities history happened on July 23–24, 1987. Known locally as The Super Storm, this event brought more rain than any other recorded event. The storm damaged 9,000 homes, killed two people, and caused $27 million in damage. Some areas in the southern metro area received 11 inches (279 mm) of rain. The 9.15 inches (232 mm) that fell on July 23 is the highest official single-day rainfall for the Twin Cities. Overall, at least 10 inches (254 mm) of rain fell over 93 square miles (241 km²), and at least 4 inches (100 mm) fell over 1,460 square miles (3,781 km²). This event was ranked the eighth most significant weather event in Minnesota during the 20th century. Three days before this event, on July 20–21, up to 9 inches (230 mm) of rain fell in some of the same areas. These two storms combined to make the Twin Cities’ wettest summer on record, with 23.52 inches (597 mm) of rain falling from June to August.
The Minnesota River and Mississippi River both flow through the Twin Cities, and river flooding happens almost every year. The worst floods on these rivers in Twin Cities history occurred in 1965. Other major floods happened in 1969, 1993, 1997, and 2001.