Excess rainfall from storms (i.e. severe thunderstorms, hurricanes, extratropical cyclones) can produce short-term and long-term flooding conditions both locally and regionally. The frequency of extreme rainfall events has increased across the southeast over the past twenty years. Increases in extreme rainfall events are most prevalent across the lower Mississippi River Valley and along the northern Gulf Coast. Most climate models are in agreement that the number of days with extreme rainfall events (more than 4 inches) will continue to increase throughout the century.
Relative to the climate region, precipitation increase is accumulated precipitation above the average values. Across the southeast, there has been a long-term upward trend of accumulated precipitation during the fall. In general, precipitation is expected to continue to increase during the fall, winter, and spring months.
Lack of rainfall can lead to short and long-term drought conditions across the region. Over the past few decades, there has been a downward trend in rainfall during the summer months. Most climate models simulate that the decrease in summer rainfall may continue into the future. Additionally, the annual mean precipitation is expected to decrease across the western portion of the Southeast.
Above average temperatures can negatively impact crop yields and introduce new pests and pathogens. Since the 1970s, temperatures have steadily increased across the southeast. It is most distinct during the summer, especially along the Gulf and Atlantic coasts. Additionally, there has been an increase in the number of days exceeding 95°F. Climate models agree that annual temperatures will continue to increase in the future as well as an increase in days exceeding 95°F.
Hurricanes and tropical storms produce a multitude of impacts ranging from damaging winds, inland flooding, coastal surges, and sometimes an isolated tornado. Tropical storms most frequently make landfall along the North Carolina Outer Banks, southern Florida, and southeast Louisiana. There has been a slight increase in the frequency of tropical storms in the Atlantic. The frequency of major hurricanes (category 3-5) will likely increase, while the number of tropical storms will decrease.
Above average temperatures can negatively impact crop yields and introduce new pests and pathogens. Temperatures have remained above average annually and especially during the winter and spring season across the northeast. Since the 1980s, the number of heat waves was moderately high. Climate models simulate an increase in the average temperature as well as temperature extremes by the end of the century. Additionally, the number of days exceeding 95°F is projected to increase.
The Northeast is subject to nor’easters which have the ability to produce significant rain and snow amounts. Over the past 30 years, an increase in the amount of extreme precipitation (both rain and snow) has occurred all across the region. The greatest increase being 30% in parts of New York while the smallest occurred mainly along the coastal regions at 9-12%. Climate models project that extreme precipitation will continue to increase into the century.
The Northeast is especially susceptible to the hazardous impacts due to sea level rise. Coastal flooding and erosion can interfere with ecosystems and species along the coast. Over the 20th century, coastal flooding has increased due to the fact the sea level rose approximately 1.2 inches per decade.
Above average temperatures can negatively impact crop yields and introduce new pests and pathogens. There was an upward trend in annual temperature and especially night and winter temperatures across the Midwest. The frequency of extremely cold winters has decreased as most recent winters were much above average. Climate models simulate an increase in the annual temperature as well as throughout all seasons across the region. The number of day’s consecutive and singular days with temperature exceeding 95°F is projected to increase, too.
Since the late 20th century, the freeze-free season has gradually increased. The last spring freeze has been occurring earlier and the first fall freeze has been occurring later. This increase is expected to continue into the 21st century, with climate models simulating an increase of up to 26 days annually across most of the Midwest.
The Midwest is susceptible to various precipitation extremes due to severe storms and frequent winter storms. In recent decades, the number of extreme precipitation (both rain and snow) events has increased significantly across most of the region. Climate models simulate that number of days exceeding one inch of precipitation will continue to increase into the 21st century.
Annually, precipitation has increased about 0.31 inches per decade across the Midwest. Most of the precipitation increases occurred during the warm season. Annual snowfall amounts have decreased across the western and southern portion, while snowfall increased along the northern portion. Climate models simulate an increase in average annual precipitation along the northern tier and a decrease in the southwestern portion. Generally, the upward trend will continue during the winter, spring, and fall across much of the region, while the southern portion is expected to decrease during the summer.