Multiple factors may contribute to increasing drought risk across the Midwest. Trends of higher temperatures, longer growing seasons, and more multi-day periods without rainfall may have compounding effects. Additionally, vapor pressure deficit (the difference between how much moisture is in the air and the amount of moisture the air can hold at saturation) is projected to increase by 20-80% by the end of the century across a range of climate scenarios. This will lead to a net drying effect as the air draws more moisture out of plants and soil. Surface soil moisture is generally expected to decline across the Midwest by the end of the century, although there will be considerable local variation based on soil type, vegetation, topography, and local hydrology.