Kansas Trends and Changes in Temperature, Precipitation, Drought, and Frost-Free Days from the 1890s to 2015

Kansas extends 660 km from the moderate elevations and semi-humid conditions of the Lower Missouri Basin to the High Plains lying above the Ogallala Aquifer and along the Rockies' eastern slope. Such characteristics result in significant climate variability across the state, making timely and accurate climate trend and change information valuable for water resources management and crop production. Here we used high-quality daily and monthly climate observations spanning a long-term period of 121 years (1895-2015) to assess trends and changes in air temperature, precipitation, drought, and frost-free days across Kansas. We show that a statewide average warming rate of 0.06 degrees C (0.11 degrees F) per decade was mainly driven by trends in daily minimum temperatures. However, there were no statistically significant trends in precipitation in either western, central, or eastern Kansas. Western Kansas tended toward increasing dryness, but central and eastern Kansas trended wetter as indicated by changes in the Palmer Drought Severity Index (PDSI), a trend that was consistent with a weak wetting signal in eastern Kansas. The length of frost-free season increased by 5.2 days in western, 7.2 days in central, and 12.6 days in eastern Kansas, which reflected more warming in the east and less in the west, especially for changing magnitudes of nighttime temperatures. Such increases of frost-free days, especially in moisture-limited areas (e.g., western Kansas), might increase seasonal evapotranspiration loss, thus exacerbating soil moisture stress and associated management challenges.