September is typically associated with the transition from summer to autumn. However, across the country, it offers a fascinating spectrum of temperatures. While some regions still have the warmth of late summer, others experience a noticeable chill in the air as they prepare for the impending fall season. Here, we explore the top 15 coldest states in September, which are ranked by the lowest temperatures they commonly encounter during September.
1. Alaska
It should come as no surprise that Alaska tops our list as the coldest state in September. With its vast expanse and northerly location, Alaska experiences frigid temperatures, especially in its northern and interior regions. In some areas, temperatures can drop below freezing, with Barrow and Fairbanks frequently recording temperatures between 20-30°F during September nights.
Average Temperature
September temperatures in Alaska vary significantly based on the region. In the southern coastal areas like Anchorage, the average highs range from 50°F to 60°F, while the northern cities such as Barrow and Fairbanks experience average highs in the 30-50°F. Nighttime lows can drop well below freezing.
Coldest Temperature on Record
The coldest temperature ever recorded in Alaska occurred on January 23, 1971, in Prospect Creek Camp, where the mercury plummeted to a chilling -80°F.
Population
Alaska, despite its vast size, is sparsely populated. In 2021, it had a population of approximately 731,000 people. Consequently, its population density is one of the lowest in the United States.
Wildlife
Alaska is also renowned for its diverse wildlife. The state is home to iconic species like grizzly bears, moose, bald eagles, and wolves. The cold temperatures in September, therefore, mark the beginning of the salmon spawning season, drawing brown bears to the rivers to feast on this essential food source.
2. Montana
Montana is known for its rugged landscapes and dramatic weather changes. It is also the second coldest state in September. As fall approaches, temperatures plummet, especially in the mountainous regions. Places like Butte and Helena can experience overnight lows in the low 30s°F, reminding residents that winter is just around the corner.
Average Temperature
In September, Montana experiences a significant temperature drop from the summer. Average highs range from 60-70°F in the west, including Missoula, to 50-60˚F in places like Butte and Helena. Nighttime lows often dip into the 30s and 40s in degrees Fahrenheit.
Coldest Temperature on Record
Montana’s lowest recorded temperature occurred on January 20, 1954, in Rogers Pass, a frigid -70°F.
Population
Montana had a population of approximately 1.08 million people in 2021. Despite its large land area, it is one of the least densely populated states in the U.S.
Wildlife
Montana’s diverse ecosystems support a range of wildlife. In September, visitors might spot elk and deer preparing for the mating season, while bighorn sheep roam the mountains. Birdwatchers can also enjoy sightings of bald eagles, golden eagles, and various migratory species passing through.
3. Wyoming
Wyoming, another state with significant elevation variations, ranks third on our list. Places like Casper and Cheyenne often see September lows in the low 30-40°F. The higher-altitude areas, like Yellowstone National Park, can even witness sub-freezing temperatures.
Average Temperature
September in Wyoming brings cooler temperatures, with average highs ranging from the 60sËšF in cities like Casper and Cheyenne to the 50sËšF in Yellowstone National Park. Nighttime lows often drop into the 30s and 40s in degrees Fahrenheit.
Coldest Temperature on Record
The state’s record low occurred on February 9, 1933, in Moran, dropping to -66°F.
Population
Wyoming had a population of approximately 580,000 people in 2021. It’s the least populous state in the country, known for its wide-open spaces.
Wildlife
Wyoming is famous for its national parks, including Yellowstone and Grand Teton, teeming with wildlife. September is therefore an excellent time to witness the elk rut in Yellowstone, with bugling elk echoing through the valleys. Visitors might also encounter bison, grizzly bears, and pronghorn in their natural habitats.
4. Idaho
Idaho, with its diverse geography ranging from fertile valleys to lofty peaks, comes in fourth place. In cities like Boise and Coeur d’Alene, September nights can be quite chilly, with temperatures hovering around the mid-30s in degrees Fahrenheit. The higher elevations in the state, including Sun Valley, can experience even colder conditions.
Average Temperature
In September, Idaho experiences a cooling trend, with average highs ranging from the 60sËšF in cities like Boise to the 50sËšF in higher-elevation areas like Sun Valley. Nighttime lows can also dip into the 30s and 40s in degrees Fahrenheit.
Coldest Temperature on Record
The coldest temperature recorded in Idaho was -60°F in Island Park Dam on January 18, 1943.
Population
As of 2021, Idaho had a population of around 1.8 million people, making it one of the fastest-growing states in the U.S.
Wildlife
Idaho has diverse wildlife, including populations of elk, mule deer, and white-tailed deer. In September, the state’s forests and mountains come alive with the vibrant colors of fall, thus providing a stunning backdrop for observing these animals in their natural habitats.
5. Vermont
Located in the northeastern part of the United States, Vermont is the fifth one on the list. As the Green Mountain State transitions into fall, places like Burlington and Montpelier can experience September lows in the upper 30s°F. The onset of foliage season adds to the charm of this chilly month.
Average Temperature
September in Vermont has average highs in the 60s°F and nighttime lows in the upper 30s°F. Cities like Burlington and Montpelier experience these cooler temperatures, which are perfect for enjoying the changing foliage.
Coldest Temperature on Record
Vermont’s record low was -50°F in Bloomfield on December 30, 1933.
Population
Vermont’s population was approximately 623,000 people as of 2021. It is one of the smallest and least populous states in the U.S.
Wildlife
Vermont’s woodlands and wetlands provide habitat for various wildlife species, including white-tailed deer, black bears, and moose. September marks the beginning of the deer rut, making it an excellent time for wildlife enthusiasts to observe these majestic creatures.
6. New Hampshire
New Hampshire, nestled in the heart of New England, follows closely behind Vermont in terms of September chill. Cities like Concord and Manchester can witness overnight lows in the upper 30s°F.
Average Temperature
New Hampshire’s September temperatures have average highs around 60°F and nighttime lows in the upper 30°F. Cities like Concord and Manchester embrace autumn, visible in the leaves changing colors.
Coldest Temperature on Record
The state’s record low was -47°F in Berlin on January 22, 1885.
Population
New Hampshire had a population of approximately 1.37 million people in 2021, making it one of the smaller states in terms of population.
Wildlife
New Hampshire also offers opportunities for wildlife enthusiasts to spot black bears, bobcats, and wild turkeys. September’s cooler temperatures also mark the start of bird migration. During this time, waterfowl like ducks and geese make their way through the state.
7. Maine
Maine ranks seventh on our list. In cities like Portland and Bangor, September temperatures often dip into the upper 30s°F. The state’s northern reaches, including Presque Isle, can experience even colder nights.
Average Temperature
In September, Maine experiences average highs in the 60s°F and nighttime lows in the upper 30s°F. Cities like Portland and Bangor also embrace the changing seasons as fall settles in.
Coldest Temperature on Record
Maine’s record low was -50°F in Clayton Lake on January 16, 2009.
Population
In 2021, Maine had a population of approximately 1.34 million people. Its vast forests and picturesque coastline attract residents and tourists, but it still remains small and sparsely populated.
Wildlife
Maine’s wilderness areas are also home to an array of wildlife, including moose, white-tailed deer, and bald eagles. September marks the onset of the moose rut. Thus, it provides wildlife enthusiasts a chance to witness these massive mammals in their natural behavior.
8. South Dakota
South Dakota is located in the northern Plains and secures the eighth spot on our list. In places like Rapid City and Pierre, September lows frequently fall into the low 40s°F. As summer fades away, residents prepare for the cooler months ahead.
Average Temperature
South Dakota sees a transition to cooler weather in September with average highs in the 60s°F and nighttime lows in the low 40s °F. Cities like Rapid City and Pierre prepare for the arrival of autumn by shedding leaves off of trees.
Coldest Temperature on Record
The state’s record low was -58°F in McIntosh on February 17, 1936.
Population
South Dakota had a population of around 900,000 people in 2021. Its vast landscapes and historic sites draw visitors year-round, yet it has a small population.
Wildlife
South Dakota is also famous for its Badlands and the wildlife that calls it home, including bison, pronghorn, and coyotes. September is therefore an excellent time for birdwatchers. During this time, numerous species of waterfowl and raptors pass through the state during their fall migration.
9. North Dakota
North Dakota, its neighbor to the north, also experiences a considerable chill in September, making it our ninth coldest state. Cities like Bismarck and Fargo often see nighttime temperatures in the low 40s °F.
Average Temperature
North Dakota experiences cooler September temperatures with average highs in the 60s°F and nighttime lows in the low 40s°F.
Coldest Temperature on Record
North Dakota’s record low was -60°F in Parshall on February 15, 1936.
Population
North Dakota had a population of approximately 770,000 people in 2021. Its vast prairies and agricultural landscapes define the state and also ensure a small population.
Wildlife
North Dakota’s grasslands also provide critical habitat for a variety of wildlife, including pronghorn, mule deer, and pheasants. In September, waterfowl hunters also flock to the state to pursue ducks and geese during their fall migration.
10. Minnesota
Minnesota, with its multitude of lakes and forests, ranks tenth on our list. As September arrives, cities like Minneapolis and Duluth can experience overnight lows in the low 40s °F. The changing leaves reflect the onset of fall in this northern state.
Average Temperature
September in Minnesota means average highs in the 60s °F in cities like Minneapolis and Duluth. Nighttime lows can often drop into the low 40s˚F.
Coldest Temperature on Record
The state’s record low was -60°F in Tower on February 2, 1996.
Population
In 2021, Minnesota had a population of approximately 5.7 million people. Its numerous lakes and outdoor recreational opportunities also attract residents and tourists. This means that despite its cold weather, the state still appeals to a lot of people.
Wildlife
Minnesota’s forests, lakes, and wetlands are also home to a wide range of wildlife, including white-tailed deer, black bears, and loons. September is therefore a prime time for birdwatching. This is because migratory birds such as warblers and sandhill cranes pass through the state.
11. Colorado
Colorado, known for its stunning Rocky Mountains, comes in eleventh place. While the state’s lower elevations in cities like Denver may not experience extreme cold in September, areas like Aspen and Vail can see temperatures dip into the low 40s°F. Therefore, this assists with the winter sports season in the few months ahead.
Average Temperature
Colorado’s September weather varies by elevation. In cities like Denver, average highs are in the 70s°F, while in high-altitude areas like Aspen and Vail, highs may only reach the 60s°F. Nighttime lows can also drop into the 30s°F.
Coldest Temperature on Record
The state’s record low was -61°F in Maybell on February 1, 1985.
Population
Colorado had a population of approximately 5.8 million people in 2021. Its diverse landscapes, including the Rocky Mountains, also draw residents and outdoor enthusiasts. This is what contributes to the relatively large population of the state.
Wildlife
Colorado’s mountains are also inhabited by iconic species like elk, mule deer, and bighorn sheep. September is therefore a popular time for elk mating rituals, with the bugling calls of bull elk echoing through the high country.
12. Wisconsin
Wisconsin is a state known for its cheese as well as its picturesque landscapes. Therefore, it secures the twelfth position on our list of the coldest states in September. Cities like Milwaukee and Madison often experience September lows in the low 40s°F, as they set the stage for autumn’s arrival.
Average Temperature
September in Wisconsin sees average highs in the 60s°F and nighttime lows in the low 40s°F in cities like Milwaukee and Madison. Fall colors start to appear, setting a picturesque scene in the state.
Coldest Temperature on Record
The state’s record low was -55°F in Couderay on February 2, 1996.
Population
Wisconsin had a population of approximately 5.8 million people in 2021. The state is known for its dairy production and outdoor recreational opportunities and therefore, has a high population.
Wildlife
Wisconsin’s forests and lakes also provide habitat for white-tailed deer, black bears, and a variety of bird species. September is, therefore, an excellent time for birdwatching, as migratory birds pass through on their way south for the winter.
13. Oregon
Oregon, with its diverse geography spanning from the Pacific coastline to the Cascade Mountains, ranks thirteenth in the list of the coldest states in September. In cities like Portland and Eugene, September nights can be chilly, with temperatures hovering around the mid-40s°F. The state’s higher elevations, including Mount Hood, can experience even colder conditions.
Average Temperature
In September, Oregon’s coastal areas like Portland experience average highs in the 60s°F, while cities like Eugene have highs in the 70s°F. Nighttime lows often drop into the 40s°F.
Coldest Temperature on Record
The state’s record low was -54°F in Seneca on February 10, 1933.
Population
In 2021, Oregon had a population of approximately 4.2 million people. The state’s natural beauty, including Crater Lake and Mount Hood, attracts residents and visitors. However, the state’s residents, while numerous, are still very protective of their natural lands.
Wildlife
Oregon’s diverse ecosystems are also home to a variety of wildlife, including black-tailed deer, cougars, and bald eagles. September is therefore a great time for birdwatchers like in other states, as migratory birds stop over in Oregon’s wetlands and forests.
14. Michigan
Michigan is surrounded by the moderating power of the Great Lakes. Yet, it is our fourteenth coldest state in September. Cities like Detroit and Lansing typically experience nighttime temperatures in the mid-40s°F. As the summer tourism season winds down, locals and visitors alike embrace the cooler weather.
Average Temperature
September in Michigan brings cooler temperatures with average highs in the 60s°F in cities like Detroit and Lansing. Nighttime lows can drop into the low 40s°F.
Coldest Temperature on Record
The state’s record low was -51°F in Vanderbilt on February 9, 1934.
Population
In 2021, Michigan had a population of about 10 million people. The state is known for its Great Lakes, forests, and automotive industry, and these also contribute to its huge population for its small size.
Wildlife
Michigan’s forests and lakes also support a variety of wildlife, including white-tailed deer, black bears, and loons.
15. Washington
Last one on our list of the top 15 coldest states in the country is Washington, the Evergreen State, which often experiences cool September nights. In cities like Seattle and Olympia, temperatures can drop into the mid-40s°F, signaling the start of the rainy season in the Pacific Northwest.
Average Temperature
September in Washington means average highs in the 60s°F in cities like Seattle and Olympia. Nighttime lows can drop into the mid-40s°F. This is also when the rainy season begins.
Coldest Temperature on Record
The state’s record low was -48°F in Winthrop on December 30, 1968.
Population
In 2021, Washington had a population of approximately 7.8 million people. The state’s diverse landscapes, including the Olympic Peninsula and Cascade Range, attract residents and tourists. This also contributes to the state’s huge population.
Wildlife
Washington’s ecosystems are home to species like Roosevelt elk, black bears, and bald eagles. September marks the start of salmon spawning, drawing in predators like orcas and bald eagles to feed on them.
Summary Table of the Top 15 Coldest States in September
Rank | State | Average Temperature in September (°F) | Coldest Temperature on Record (°F) | Wildlife Overview |
---|---|---|---|---|
1 | Alaska | 43.6 | -80 | Diverse wildlife, including bears, moose, and bald eagles. |
2 | Montana | 57.1 | -70 | Home to bison, elk, and mountain goats, with Yellowstone National Park. |
3 | Wyoming | 57.7 | -63 | Offers habitat for bison, pronghorn, and grizzly bears. |
4 | Idaho | 61.2 | -60 | Features diverse ecosystems, including forests and high mountain ranges. |
5 | Vermont | 61.3 | -50 | Abundant wildlife, including white-tailed deer, moose, and black bears. |
6 | New Hampshire | 63.3 | -50 | Home to white-tailed deer, foxes, and various bird species. |
7 | Maine | 61.2 | -48 | Features extensive forests and is known for its lobster industry. |
8 | South Dakota | 63.5 | -58 | Bison herds roam the prairies, and the Black Hills offer diverse wildlife. |
9 | North Dakota | 62.7 | -60 | Prairies and badlands support bison, pronghorn, and coyotes. |
10 | Minnesota | 63.9 | -60 | Home to moose, wolves, and loons, with numerous lakes and forests. |
11 | Colorado | 66.5 | -61 | Diverse ecosystems with elk, mule deer, and mountain lions. |
12 | Wisconsin | 63.1 | -55 | Abundant wildlife, including white-tailed deer and black bears. |
13 | Oregon | 64.3 | -54 | Diverse ecosystems with black-tailed deer, cougars, and bald eagles. |
14 | Michigan | 62.2 | -51 | Known for the Great Lakes and wildlife like black bears and loons. |
15 | Washington | 65.1 | -48 | Diverse landscapes host Roosevelt elk, black bears, and bald eagles. |
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