Large variation exists for projected changes in precipitation for Michigan and the Upper Midwest. Although individual model projections may differ, there is general agreement that annual precipitation is expected to increase slightly (2 to 4 inches) during the 21st century. Models also tend to agree that precipitation patterns between seasons may shift substantially. Averages across multiple climate models indicate that winter and spring may experience 20-30% more precipitation by the end of the century, while summer precipitation is projected to decrease by less than 10%. As seasonal precipitation changes, it is reasonable to expect that soil moisture regimes will also change. Longer growing seasons and warmer temperatures may also result in greater evapotranspiration losses and lower soil-water availability later in the growing season. 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. Model outputs indicate that forests in northern Minnesota may become increasingly moisture-limited under climate change. This may be the case particularly in locations where soils and landforms do not allow precipitation from intense events to be retained.