The United States experienced its hottest July on record, with average temperatures across the Lower 48 states surpassing a record that had stood since the Dust Bowl era, according to the National Oceanic and Atmospheric Administration.

The average temperature across the contiguous US reached 76.89°F (24.94°C) in July, 3.3°F (1.8°C) above the 20th-century average. The figure narrowly exceeded the previous July record set in 1936, when severe drought and extreme heat caused widespread devastation across the country.

The new record followed weeks of intense heatwaves, prolonged periods of extreme temperatures and widespread wildfires.

Heat domes fuel record temperatures

Three major heat dome events developed across the US during July, trapping hot air over large parts of the country under persistent high-pressure systems.

The West, Rockies, Upper Midwest, Gulf Coast and Southeast all experienced prolonged periods of extreme heat. NOAA said every state in the Lower 48 recorded a July average at least 1°F (0.6°C) above its 20th-century average.

Wyoming recorded its hottest July as well as its hottest month ever, with average temperatures 5.1°F above normal.

One of the most significant factors behind the national record was unusually warm overnight temperatures. The average minimum temperature across the Lower 48 exceeded the previous record by 0.7°F.

Meteorologists say elevated nighttime temperatures can make heatwaves particularly dangerous because the human body has less opportunity to recover from daytime heat.

“If you’re talking heat waves, that nighttime low is incredibly important for determining total heat stress,” meteorologist Jeff Masters of Yale Climate Connections said. “So if it doesn’t cool off at night, your body doesn’t have time to readjust to all the heat.”

Heatwaves linked to wider climate concerns

The extreme temperatures coincided with widespread wildfires in the Pacific Northwest and Canada, sending smoke across large parts of North America.

Scientists have increasingly linked the rising frequency and intensity of extreme heat and wildfire conditions to human-driven climate change and the continued burning of fossil fuels.

The record-breaking heat also disrupted daily life for millions of Americans. An AP-NORC poll found that nearly half of respondents said higher electricity bills caused by increased air-conditioning use had a major impact on their finances.

Around 40 per cent said extreme heat disrupted their travel plans, while roughly two-thirds reported changes to family outdoor activities. About half said the heat affected their exercise routines.

Masters said the fact that July’s record surpassed a benchmark set during the Dust Bowl era was particularly concerning, given the severe drought and heat that devastated large parts of the US in the 1930s.

The latest record adds to growing concerns over the increasing frequency of prolonged and intense heat events across the United States.