11. Northern California
In February of 2019, record-setting levels of rain in California led to floods throughout the northern part of the state. Scientists predict that extreme precipitation events will continue to increase in intensity in California in the future, as well as greater variability between wet and dry years — meaning more droughts and more floods. One study published in the May 2018 edition of the peer-reviewed journal Nature Climate Change found that wet extremes in California will increase by 100% to 200% by 2100.
12. Southwest: Colorado, Utah
Snowpack in the western states was dramatically lower in the winter of 2017-18. By mid-February, statewide snowfall had fallen to 49% of normal in Utah, and 85% below average in Colorado. According to the National Climate Assessment, the reduced snow levels are part of a larger trend of declining winter snowpack throughout the southwestern United States over the last 50 years, due largely to warmer temperatures that cause precipitation to fall as rain rather than snow and cause existing snowpack to melt earlier in the year.
Snow drought can lead to reduced water availability in the summer and have negative impacts on economies that rely on outdoor tourism and recreation. Snow drought can also have other impacts on people, agriculture, and wildlife.
13. Western United States
After historic amounts of rain fell in the winter of 2016-17 and snowpack levels rose, much of the western United States experienced an early spring melt, leading to increased risk of flooding and dangerous fluctuations in river flow. The faster snowmelt is partially the result of warmer temperatures earlier in the year, causing spring conditions to arrive as many as 20 days earlier than normal in some parts of the country. Scientists say because of human-caused climate change, spring is beginning about 2.5 days earlier every decade on average.
14. West: California, Arizona
According to the Third U.S. National Climate Assessment, heat waves in the United States have become more frequent since the 1960s, while the frequency of cold waves has declined. The annual average temperature over the contiguous United States has risen 1.8 degrees from 1901 to 2016 and is projected to increase an additional 2.5 degrees from 2021 to 2050.
New all-time heat records were set in the summer of 2019 in places such as Palm Springs, California, as well as Phoenix and Tucson, Arizona.
15. Northeast: Pennsylvania, New York, New Jersey
In August 2018, historic levels of rainfall led to disaster declarations in several counties in New Jersey, and substantial flooding throughout parts of New York and New Jersey. According to the Environmental Protection Agency, flood events have increased in frequency and intensity throughout much of the Northeast since 1965.