Recent analysis by the Associated Press reveals that climate change has significantly increased humidity levels in the eastern United States, affecting over 70 million people during the past two intensely hot summer months.
This spike has led to extremely warm and potentially hazardous nights in many cities, as pointed out by the National Weather Service.
Record high humidity days, which meteorologists classify as uncomfortable, were reported across 27 states and parts of Washington, DC. Averages show that the dew point, a key metric for measuring humidity, hovered above 65 degrees Fahrenheit throughout June and July.
When considering daily averages, many areas have experienced prolonged humidity levels; for example, Philadelphia saw dew points over 75 degrees for 29 days, Washington for 27 days, and Baltimore for 24 days. Even Tampa officials described the conditions as oppressive.
Meteorologists highlight that the dew point is one of the most effective indicators of humidity. Compared to summer averages from 1951-2020, dew points in cities like Washington, Baltimore, Pittsburgh, and more have risen at least six degrees this summer. Moreover, humidity levels in the eastern U.S. have increased more than 66 degrees from historical averages recorded since 1950.
Bernadette Woods, the chief meteorologist at Climate Central, remarked that this summer has been notably steamy, with increased humid heat. Cameron Lee, a climate scientist and humidity specialist at Kent State University, recorded a staggering dew point of around 82 degrees at his local weather station in Ohio this summer.
Lee noted that regions of the U.S. are experiencing consistently rising humidity levels, particularly in spring and summer, contributing to a growing number of extreme humidity days. He observed that these intense weather patterns now last longer and cover larger areas.
Zach Taylor, head of operations at the National Weather Service’s Weather Forecast Center, mentioned that high moisture content inhibits the usual nighttime cooling. Cities like Virginia Beach, Nashville, and Charlotte experienced their hottest overnight lows. Similarly, areas such as New York City and Concord, New Hampshire, were not spared.
“The nighttime temperature has a real impact on your comfort,” Taylor explained. “If the nights are warm, it’s hard for your body to recover from the heat of the day. Over consecutive days, this can really take a toll, especially for those without access to cooling facilities.”
Woods highlighted the connection between climate change—driven by fossil fuel burning—and current weather patterns, noting the ongoing extreme heat and rainfall this summer.
AP data shows that summer dew points in the eastern U.S. have increased by an average of 2.5 degrees since 1950. Previously, in the mid-20th century, the norm was in the low ’60s, but the past six years have seen averages climbing above 65, pointing towards greater discomfort.
Lee remarked on the significance of dew point trends that now indicate extreme heat may occur much more frequently than in previous summers.
High humidity and heat mutually exacerbate each other. Meteorologists explain that warming by 1 degree Fahrenheit increases the air’s moisture-carrying capacity by approximately 4%, leading to significant repercussions in weather patterns.
This summer, both the Midwest and East have been shielded under intense high-pressure systems, associated with sweltering temperatures and heavy rainfall. Notably absent were the cooler fronts that typically relieve the oppressive conditions, although some relief finally arrived in August.
Humidity levels are not consistent across the country; the West tends to be drier, while the South experiences higher summer dew points than the North. However, this trend is shifting, according to Marshall Shepherd, a meteorology professor at the University of Georgia, who emphasized that uncomfortable humidity is reaching areas less accustomed to it.
He concluded with a poignant remark: “It’s not your grandparents’ summer anymore.”
