Average annual temperature has increased about 2°F since the early 20th century, with greater warming in the winter and spring than in the summer and fall. The number of very cold nights has been much below average since 1990. Under a higher emissions pathway, historically unprecedented warming is projected by the end of the 21st century.
Precipitation has varied greatly from year to year in this region of transition from humid conditions in the east of the state to semi-arid conditions in the west. Projected increases in winter precipitation and decreases in summer precipitation may result in both beneficial and negative impacts.
The agricultural economy of Kansas makes the state vulnerable to droughts and heat waves, several of which occurred in the 1930s, 1950s, and in recent years. Projected increases in temperatures may increase the intensity of future droughts. The frequency of wildfire occurrence and severity is also projected to increase in Kansas.
Kansas lies in the central Great Plains, straddling the transition from relatively abundant precipitation (more than 42 inches annually) in the southeast, supporting forests and rain-fed agriculture, to semi-arid conditions (less than 20 inches annually) in the west. The state is far from the moderating effects of oceans and temperatures vary widely across seasons. The statewide average temperature is 31.3°F in the winter and 76.6°F in the summer.
The last decade has been one of the warmest on record for Kansas, surpassed only (slightly) by the extreme heat of the 1930s Dust Bowl era (Figure 1) when extreme drought and poor land management likely exacerbated the hot summer temperatures. Many record high temperatures were set during the summer of 2012, which was the hottest year on record with an average temperature of 58.2°F. One notable trend is an increase in spring temperatures that has persisted over the last three decades (Figure 2a), which has implications for crop planting. Summer temperatures have been near to above average during the 2000s (Figure 2b). There is no long trend in very warm nights (days with minimum temperature above 75°F) and extremely hot days (days with maximum temperature above 100°F), although both have been slightly above average over the past five years (Figures 3a and 3b). The number of very cold nights (days with minimum temperature below 0°F) has been below average since 1990 (Figure 4). The freeze-free season has also lengthened, averaging 9 days longer in the 21st century than the 20th century average.
Precipitation is highly variable from year to year, with the statewide average ranging from a low of 15.34 inches in 1956 to a high of 40.58 inches in 1951. The driest multi-year periods on record occurred during the 1910s, 1930s, and 1950s, with the driest 5-year period being 1952–1956. The wettest periods were the 1940s and 1990s, with the wettest 5-year period on record being 1992–1996 (Figure 3c). The majority of precipitation falls during the warm season months, and on an annual basis, precipitation was generally above average from the mid-1980s through the late-2000s. (Figure 3d). The frequency of heavy rain events has been highly variable with a general increase; the number of 3-inch rain events has been near to above average during the last two decades (Figure 5). The increase in extreme rainfall events has been more pronounced in the eastern part of the state. Several major floods have occurred since the beginning of the 20th century. The Great Flood of 1951 extended over about half the state, with both rural and urban areas suffering severe losses, including $2.5 billion in total damages and 19 fatalities.
Severe thunderstorms are common in Kansas due to the state’s geography, which allows cold, dry air from the north to combine with warm, moist air from the Gulf of Mexico, triggering severe thunderstorms, some of which can produce tornadoes. On average, the state experiences more than 50 tornadoes each year, which occasionally cause major damage and loss of life. The Topeka tornado of June 8, 1966, one of the most destructive tornadoes in Kansas history, killed 17 people, injured more than 500, and caused over $200 million in damages (at the time, the highest in American history). Since 1950, Kansas has had six EF5 (Enhanced Fujita Scale) tornadoes, the third highest of any state. The most recent EF5 tornado occurred in May 2007, when nearly 95% of Greensburg was completely destroyed and 11 people were killed.
The agricultural economy of Kansas makes the state particularly vulnerable to droughts (Figure 6). After abnormally dry conditions in 2011, a severe drought hit in 2012 (one of the top ten driest years for the state). The critical growth months of May, June, and July were the driest on record for the state, with only 4.91 inches of rain. By August, more than 95% of the state was in extreme drought status. The drought, combined with the extreme summer heat, had significant negative impacts on crop yields, livestock production, and pasture conditions. Despite the occurrence of this very severe drought, the late 20th and early 21st centuries have been generally characterized by few short-term and long-term severe droughts.
Under a higher emissions pathway, historically unprecedented warming is projected by the end of the 21st century (Figure 1). Even under a pathway of lower greenhouse gas emissions, temperatures are projected to most likely exceed record levels by the middle of the 21st century. However, there is a large range of temperature increases under both pathways, and under the lower pathway, a few projections are only slightly warmer than historical records. Heat waves are projected to increase in intensity, posing a risk to both livestock and human health, while cold wave intensity is projected to decrease. The freeze-free season is projected to lengthen.
Although projections of overall annual precipitation are uncertain, summer precipitation is projected to decrease across the state (Figure 7), while winter precipitation is projected to increase. Winter precipitation increases could potentially benefit winter wheat production, but summer drying would have negative impacts on rain-fed summer crops and rangeland.
The intensity of future droughts is projected to increase. Droughts are a natural part of the climate system. Although projections of overall precipitation are uncertain, higher temperatures will increase the rate of loss of soil moisture during dry spells, leading to more serious conditions during future naturally-occurring droughts, including an increase in the occurrence and severity of wildfires.