The United States has reached a somber meteorological milestone. According to the latest data from the National Oceanic and Atmospheric Administration (NOAA), this past July was the hottest month ever documented in the nation’s history since record-keeping began in 1895. While July is traditionally the warmest period of the year for the country, the intensity and duration of this year’s heat surpassed previous historical benchmarks, affecting nearly every corner of the Lower 48 states.
What happened
The average temperature across the contiguous United States in July was 3.3 degrees Fahrenheit higher than the 20th-century average. This shift allowed July to edge out the previous record-holding years of 1936 and 2012 by approximately 0.1 to 0.2 degrees. The heat was not localized; 13 different states saw their monthly averages rank among the top five warmest on record. Notably, Wyoming experienced its hottest month ever recorded, regardless of the season.
The primary driver of these extreme conditions was a series of persistent “heat domes.” These high-pressure systems act like a lid on a pot, trapping hot air near the surface and preventing cooler air from circulating. Guided by the fluctuations of the jet stream, these domes migrated across different regions, bringing record-breaking maximum and minimum temperatures to cities such as Denver, Salt Lake City, Miami, and Minneapolis. Across the nation, more than 600 records for the highest daily temperatures were established during the month.
Context
While natural weather variability always plays a role, experts point to human-caused climate change as the fundamental reason these heat waves are becoming more frequent and severe. Research from Climate Central highlights a startling trend: since 1970, July temperatures in 229 American cities have risen by an average of 2.6 degrees Fahrenheit. The most rapid warming has been observed in the Southwest and the Pacific Northwest.
Adding to the complexity of this year’s weather was a strengthening El Niño event in the Pacific Ocean. While El Niño can contribute to rising global air and sea temperatures, scientists noted that the specific heat waves experienced in the U.S. were primarily the result of long-term climate trends and specific atmospheric patterns rather than the oceanic cycle alone. This domestic heat mirrored a global crisis, as Western Europe also faced its hottest start to summer on record, resulting in devastating wildfires across Greece, Spain, and France.
Why it matters
The record-breaking heat of July is a clear indicator of a shifting climate reality. Under normal conditions, record-high and record-low temperatures should occur with roughly the same frequency. However, this July saw over 600 record highs compared to fewer than 50 record lows—a lopsided ratio that demonstrates how the burning of fossil fuels has fundamentally altered the environment.
These rising temperatures have immediate and dangerous consequences. The extreme heat fueled massive wildfires across the Pacific Northwest and parts of Canada, mirroring the ecological destruction seen in Europe. Beyond the environmental impact, prolonged heat waves strain electrical grids, increase the risk of heat-related illnesses, and alter agricultural cycles. As these intense heat events become longer-lasting and more likely to occur, the record-setting July of today may soon become the standard for the summers of the future.