The Interior, home of Fairbanks and Denali National Park, has some of the most extreme weather in the world with rapid temperature swings, thunderstorms with hail and lightning and snow in the summer. Winters are very long, lasting from late September to mid-April. They are very cold and dry, with temperatures sometimes dipping down to -65 °F (-53.9 °C). Often the temperature is below zero Fahrenheit (-17.8 °C) for entire months.

The coldest temperature ever recorded in Fairbanks was -66 °F (-54.4 °C) on January 14, 1934. The average January low is -19 °F (-28.3 °C) and the average January high is -2 °F (-18.8 °C). Winter snowfall averages around 67.40 inches per year. During the winter months, if the temperature drops below -20 °F (-28.9 °C), ice fog can occur. The summers are usually very warm, with temperatures often reaching into the 80s °F and sometimes reaching into the 90s °F. The average July low is 53 °F (11.6 °C) and the average July high is 72 °F (22.2 °C).

According to the New York Times, spectacular displays of the aurora borealis (”northern lights”) are visible on an average of 200 days a year in the vicinity of Fairbanks. (Jerry Garrett, “The Cold Show in Fairbanks Alaska,” New York Times, March 2, 2007). The highest temperature ever recorded in Fairbanks was 99 °F (37.2 °C) on July 28, 1919.

Thunderstorms with hail and lightning can occur in summer. August and September can be rainy, and snow often starts falling in September. The average rainfall is 10.34 inches per year. Fairbanks is known for its lingering summer days. The sun is up for 21 hours and 49 minutes on the 21st of June with 24 hours of usable daylight. In summer the local golf clubs have all night golfing. Conversely, the sun is up for 3 hours and 42 minutes on the 21st of December with 6 hours and 33 minutes of usable daylight.

Snow cover is persistent in Fairbanks, without interruption, from October through April. Snowfalls of 4 inches or more in a day occur only three times during winter. Blizzard conditions are almost never seen, as winds in Fairbanks are above 20 miles an hour less than 1 percent of the time. Precipitation normally reaches a minimum in spring and a maximum in August, when rainfall is common. During summer, thunderstorms occur in Fairbanks on an average of about eight days.

Thunderstorms are about three times more frequent over the hills to the north and east of Fairbanks. Damaging hail or wind rarely accompanies thunderstorms around Fairbanks. There are rolling hills reaching elevations up to 2,000 feet above Fairbanks to the north and east of the city. During winter, the uplands are often warmer than Fairbanks, as cold air settles into the valley. In some months, temperatures in the uplands will average more than 10 degrees warmer than Fairbanks.

During summer, the uplands are a few degrees cooler than the city. Precipitation in the uplands around Fairbanks is heavier than it is in the city by roughly 20 to 50 percent. Fairbanks exhibits an urban heat island, especially during winter. Low lying areas nearby, such as the community of North Pole, are often colder than the city, sometimes by as much as 15 degrees.

During winter, with temperatures of -20 degrees or colder, ice fog frequently forms in the city. Cold snaps accompanied by ice fog generally last about a week, but can last three weeks in unusual situations. The fog is almost always less than 300 feet deep, so that the surrounding uplands are usually in the clear, with warmer temperatures. Visibility in the ice fog is sometimes quite low, and this can hinder aircraft operations for as much as a day in severe cases. Aside from the low visibility in winter ice fog, flying weather in Fairbanks is quite favorable, especially from February through May, when crystal clear weather is common and the length of daylight is rapidly increasing.