paragraph_text: Yellowstone National Park spans an area of 3,468.4 square miles (8,983 km), comprising lakes, canyons, rivers and mountain ranges. Yellowstone Lake is one of the largest high - elevation lakes in North America and is centered over the Yellowstone Caldera, the largest supervolcano on the continent. The caldera is considered an active volcano. It has erupted with tremendous force several times in the last two million years. Half of the world's geothermal features are in Yellowstone, fueled by this ongoing volcanism. Lava flows and rocks from volcanic eruptions cover most of the land area of Yellowstone. The park is the centerpiece of the Greater Yellowstone Ecosystem, the largest remaining nearly - intact ecosystem in the Earth's northern temperate zone. In 1978, Yellowstone was named a UNESCO World Heritage Site.

paragraph_text: The Stillwater River is a tributary of the Yellowstone River. Approximately 70 miles (113 km) long, it runs through southern Montana in the United States.

paragraph_text: The loosely defined term ``supervolcano ''has been used to describe volcanic fields that produce exceptionally large volcanic eruptions. Thus defined, the Yellowstone Supervolcano is the volcanic field which produced the latest three supereruptions from the Yellowstone hotspot; it also produced one additional smaller eruption, thereby creating the West Thumb of Yellowstone Lake 174,000 years ago. The three supereruptions occurred 2.1 million, 1.3 million, and approximately 630,000 years ago, forming the Island Park Caldera, the Henry's Fork Caldera, and Yellowstone calderas, respectively. The Island Park Caldera supereruption (2.1 million years ago), which produced the Huckleberry Ridge Tuff, was the largest, and produced 2,500 times as much ash as the 1980 Mount St. Helens eruption. The next biggest supereruption formed the Yellowstone Caldera (~ 630,000 years ago) and produced the Lava Creek Tuff. The Henry's Fork Caldera (1.2 million years ago) produced the smaller Mesa Falls Tuff, but is the only caldera from the Snake River Plain - Yellowstone hotspot that is plainly visible today.

paragraph_text: The Chief Standing Bear Memorial Bridge is a bridge across the Missouri River at the Nebraska-South Dakota border. Located near Niobrara, Nebraska, not far downstream from the confluence of the Niobrara River with the Missouri, it joins Nebraska Highway 14 to South Dakota Highway 37.

paragraph_text: The Battle of Liberty (also known as the Battle of Blue Mills Landing or the Battle of Blue Mills) was a battle of the American Civil War that took place on 17 September 1861, in Clay County, Missouri. Union forces unsuccessfully attempted to prevent pro-Confederate Missouri State Guards from northern Missouri from crossing the Missouri River near the confluence with the Blue River to reinforce Sterling Price at Lexington.

paragraph_text: Brower's Spring is a spring in the Centennial Mountains of Montana that was marked by a surveyor in 1888 as the ultimate headwaters of the Missouri River and thus the fourth longest river in the world, the -long Mississippi-Missouri River.

paragraph_text: The Chester Bridge is a continuous truss bridge connecting Missouri's Route 51 with Illinois Route 150 across the Mississippi River between Perryville, Missouri and Chester, Illinois. It is one of two motor-traffic bridges spanning the Mississippi River between St. Louis and Cape Girardeau, Missouri.

paragraph_text: Lesterville, Missouri is an unincorporated community in southeast Missouri. It is located in Reynolds County on Routes 21, 49, and 72 near the Black River.

paragraph_text: Mount Pleasant Estates is a winery in Augusta, Missouri, United States, on the north side of the Missouri River in what is called the Missouri Rhineland. It is the third-largest winery in the state.

paragraph_text: The Missouri makes a bend to the southeast as it winds through the Great Plains, receiving the Niobrara River and many smaller tributaries from the southwest. It then proceeds to form the boundary of South Dakota and Nebraska, then after being joined by the James River from the north, forms the Iowa -- Nebraska boundary. At Sioux City the Big Sioux River comes in from the north. The Missouri flows south to the city of Omaha where it receives its longest tributary, the Platte River, from the west. Downstream, it begins to define the Nebraska -- Missouri border, then flows between Missouri and Kansas. The Missouri swings east at Kansas City, where the Kansas River enters from the west, and so on into north - central Missouri. To the east of Kansas City, the Missouri receives, on the left side, the Grand River. It passes south of Columbia and receives the Osage and Gasconade Rivers from the south downstream of Jefferson City. The river then rounds the northern side of St. Louis to join the Mississippi River on the border between Missouri and Illinois.

paragraph_text: Being 1,000 miles (1,609 km) from any large body of water (with the exception of Lake Superior), temperatures and precipitation in North Dakota can vary widely. North Dakota is far enough north to experience − 60 ° F (− 51 ° C) temperatures and blizzards during the winter months, but far enough south to experience 121 ° F (49 ° C) temperatures and tornado outbreaks in the summer. The 181 ° F degree (100 ° C) variation between North Dakota's highest and lowest temperature is the 3rd largest variation of any U.S. State, and the largest of any non-mountainous state.

paragraph_text: Snowden Bridge is a high-clearance, vertical-lift railroad bridge, built in 1913, that spans the Missouri River between Roosevelt and Richland Counties in Montana, USA, between Bainville and Fairview, Montana, and near Fort Union Trading Post National Historic Site and the ghost town of Mondak near Montana's eastern border with North Dakota. Snowden Bridge is a near twin of the Fairview Bridge, which crosses the Yellowstone River in North Dakota, both bridges having been built by within ten miles of each other over different rivers in different states.

paragraph_text: The Missouri River is the longest river in North America. Rising in the Rocky Mountains of western Montana, the Missouri flows east and south for 2,341 miles (3,767 km) before entering the Mississippi River north of St. Louis, Missouri. The river takes drainage from a sparsely populated, semi-arid watershed of more than half a million square miles (1,300,000 km), which includes parts of ten U.S. states and two Canadian provinces. When combined with the lower Mississippi River, it forms the world's fourth longest river system.

paragraph_text: Waterloo is a community in Lafayette County, Missouri, United States. The community is located in west central Missouri on MO 224, near the south bank of the Missouri River. Nearby towns include Napoleon, Wellington, and Lexington.

paragraph_text: The Gardner River (also known as the Gardiner River) is a tributary of the Yellowstone River, approximately long, in northwestern Wyoming and south central Montana in the United States. The entire river is located within Yellowstone National Park. It rises on the slope of Joseph Peak, Gallatin Range in the northwestern part of the park, and winds southeast through Gardner's Hole, a broad subalpine basin which is a popular trout fishing location. Angling on the Gardner is governed by Yellowstone National Park fishing regulations. After merging with Panther Creek, Indian Creek and Obsidian Creek, it then turns north and flows through a steep canyon where it cuts through a basaltic flow from approximately 500,000 years ago known as Sheepeater Cliffs. Below Sheepeater, Glen Creek out of Golden Gate Canyon and Lava Creek out of Lava Creek Canyon join the Gardner near Mammoth Hot Springs. The river crosses the 45th parallel in Gardner Canyon and is also home to a popular hot spring known as "The Boiling River". The river continues north through Gardner Canyon and empties into the Yellowstone near Gardiner, Montana.

paragraph_text: The Boulder River is a tributary of the Yellowstone River, approximately 60 mi (96 km) long, in south central Montana in the United States. It is one of two rivers named the Boulder River in Montana.

paragraph_text: The Yellowstone River rises on the continental divide near Younts Peak in Wyoming's Teton Wilderness. It flows north through Yellowstone National Park, enters Montana near Gardiner, and passes through the Paradise Valley to Livingston. It then flows northeasterly across the state through Billings, Miles City, Glendive, and Sidney. The Yellowstone joins the Missouri in North Dakota just east of Fort Union. It is the longest undammed, free-flowing river in the contiguous United States, and drains about a quarter of Montana (36,000 square miles (93,000 km2)).

paragraph_text: The Yellowstone Club, also Yellowstone Ski Resort, is a private residential club, ski resort, and golf resort located in the state of Montana, USA. The Rocky Mountain ski and golf club is located in eastern Madison County, just west of Big Sky, Montana, south of Bozeman and northwest of Yellowstone National Park.

paragraph_text: St. Charles is a city in, and the county seat of, St. Charles County, Missouri, United States. The population was 65,794 at the 2010 census, making St. Charles the ninth - largest city in Missouri. It lies to the northwest, and is a suburb of St. Louis, Missouri on the Missouri River.

paragraph_text: The Harry S Truman Bridge is a vertical lift rail drawbridge over the Missouri River connecting Jackson County, Missouri with Clay County, Missouri in Kansas City, Missouri. It has a 427 foot main span, and is the tenth longest span in the United States.

Question: When does it get cold in the state where the Yellowstone meet the Missouri river?
Answer: winter months