The climate of Bismarck in the U.S. state of North Dakota is humid continental (Köppen Dfa/Dfb), caused primarily by the combination of its mid-level latitude and location not far from the geographic centre of the U.S. Its summers are hot enough for it to border on having a Köppen Dwa classification, and precipitation is high enough for it to barely avoid being classified as semi-arid (Köppen climate classification BSk). The city's climate displays four very distinct seasons and great variation in temperatures over very short periods of time. Like other cities in the northern Great Plains, its climate is also fairly dry.
Temperatures in Bismarck are variable throughout most of the year, with some stability in summer due to the yearly weakening of the jet stream. Nevertheless, there are four very distinct seasons, with great temperature variation. The warmest month of the year is July, when the average high temperature is 84.5F. Overnight low temperatures in July average 56.4F. The coldest month of the year is January, with an average high temperature of 21.1F and lows of -0.6F on average.
Highs exceed 90F on 21 days per year, and 50F for only 17 days from November to March. Highs reach the freezing mark on about one-third of the days from December to February, and lows reach 0F or below on 42 nights per year.
The highest temperature ever recorded in Bismarck was 114F, on July 6, 1936.[1] The temperature has reached or exceeded 110°F in Bismarck a total of five times in recorded weather history. Two of those occasions were in the same five-year period: 111°F in June 2002, and 112°F in July 2006. The coldest temperature ever recorded in Bismarck was -45F, on both January 13, 1916 and February 16, 1936.
The climate of Bismarck tends to be dry, with yearly precipitation averaging only 16.8inches. The wettest month of the year on average is June, when a majority of precipitation falls as rain from thunderstorms. June averages 2.59inches of precipitation.[1] December is the driest month, averaging only 0.44inches,[1] as precipitation falls as fluffy, low moisture-content snow. In the winter, Bismarck averages 49.3inches of snow annually.
The 1990s were a very moist period for Bismarck. The earlier part of the decade was documented for heavy snowfall as the snowiest winter on record in Bismarck was the winter of 1996–97, when 101.6inches of snow fell. The decade was noted for heavy rainfall as well as 4.63inches of rain fell, the most rain ever received in a standard 24-hour day, on August 21, 1998. In addition, just one year later, the second highest 24-hour rainfall occurred on August 12, 1999, with 4.48inches.[2] This wet period led into an extended drought period in the early 2000s that continued into 2006.
The area averages 4 hours of daily sunshine in December.[3] July is the sunniest month, with an average 11.4 hours of daily sunshine.[3] The total of around 2740 hours of sunshine per year means that the area receives 62.53% of possible sunshine.[3]