(CNN) — July was the hottest month ever recorded in the United States, according to data released Monday by the National Oceanic and Atmospheric Administration. The month featured long, intense heat domes that led to record hot temperatures from the East Coast to the Plains and Southwestern states. NOAA’s temperature records date back to 1895.
By the end of the month, large wildfires were burning in the Pacific Northwest and Canada, mirroring what has been taking place in Europe, which is having its hottest summer on record.
July’s average temperature in the Lower 48 states was 3.3 degrees Fahrenheit above the 20th-century average, NOAA reported. This was about 0.1 to 0.2 degrees warmer than July 1936 and July 2012 — the previous record holders — NOAA stated.
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July tends to be the hottest month of the year in most of the US. More than 600 monthly records for highest maximum and minimum temperatures have been set this year in July across the US. There were fewer than 50 monthly records set on the cool side for temperatures. In any given month those should average out to be even. Climate change due to the burning of fossil fuels has altered this pattern.
One feature of the July weather pattern in the US was a seemingly endless series of heat domes that popped up in different parts of the country depending on the contortions of the jet stream. Heat domes act like a lid on a pot, trapping and enhancing hot air beneath them. The jet stream is a narrow corridor of fast-moving air at about 30,000 feet above the Earth’s surface, and it plays a key role in steering and providing energy for weather systems.
Long-term, human-caused climate change is making heat waves more intense, longer-lasting and more likely to occur. Last month saw an intense heat wave that enveloped the eastern half of the country through the July 4th holiday weekend, with subsequent rounds of extreme heat that hit after that as well.
Above average temperatures stretched across the entirety of the Lower 48 states, with 13 states having monthly average temperatures that ranked in their top-5 warmest Julys. Wyoming had its hottest July and hottest month of any month on record. No state had a ranking near or below average for the month, NOAA found.
July has been warming especially rapidly during the past few decades. According to Climate Central, a research and communications nonprofit, in 229 US cities, July temperatures have climbed an average of 2.6 degrees since 1970, with the highest rates of warming occurring in cities in the Pacific Northwest and the Southwest.
Cities that had their warmest Julys include Denver and Salt Lake City, as the Intermountain West had the most significant heat compared to average last month. But many cities across the country had a month that ranked in the top-5 warmest, including Miami, L.A. and Minneapolis.
In addition to long-term climate change, a rapidly intensifying El Niño event in the tropical Pacific Ocean is also beginning to be a factor in elevating global average sea and air temperatures and may have played a supporting role in increasing July’s air temperatures across the US.
However, studies showed that individual heat waves that struck the country were more connected to climate change plus the natural variability of weather systems than El Niño.
July’s extreme heat was not limited to the US, as much of Europe saw multiple heat waves that led to wildfire outbreaks at the end of the month and into early August in Spain, France, the UK, Greece and other countries. According to the Copernicus Climate Change Service, Western Europe has had its hottest first two months of summer on record so far.
Extreme weather continues into early August
The onslaught of extreme weather has continued into August in North America and Europe, from deadly and record-setting blazes in Washington and Oregon, to additional heat waves and wildfires scorching both the US and Western Europe.
A complex of three wildfires damaged or destroyed hundreds of homes and other structures in Spokane, Washington last week, amid extremely dry, windy and hot conditions that were conducive to the rapid spread of flames.
In addition, extreme heat, drought and a dearth of winter snowfall led Lake Mead, the country’s largest reservoir, to hit a record low level last week. The reservoir supplies water to 20 million people in multiple Southwestern states.
CNN meteorologist Brandon Miller contributed reporting.
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