July was California’s hottest month in history

A man fishes off a jetty in Alameda, California, as the sun sets over the San Francisco Bay on 1 July. Photograph: Noah Berger/AP

California experienced its hottest month on record in July as grueling heat baked the American west for weeks on end.

The state’s average temperature for the month was 81.7F (27.6C), according to the National Centers for Environmental Information, but some areas endured days of temperatures greater than 100F (about 38C). Several cities broke temperature records during a heatwave in early July – Palm Springs hit 124F on 5 July, while Redding in the state’s far north saw a high of 119F on 6 July.

Death Valley, the hottest place on Earth, recorded its hottest month ever in July, according to the National Park Service (NPS). In Nevada, Las Vegas reached 120F on 7 July, its hottest day in history, and set a record for number of days over 115F.

The impacts of extreme heat are being felt across the US and the world as the climate crisis drives increasingly severe and dangerous weather conditions. Last month about one-third of the US population was under warnings for record heat. The Earth saw its hottest day in recorded history on 22 July, breaking a record set just one day earlier.

Extreme heat poses major health risks and is the mostly deadly type of weather-related disaster. It is particularly dangerous for unhoused people and seniors as well as those who don’t have access to cooling spaces.

California’s high temperatures in July also helped dry out vegetation and fuel wildfires across the state. Late last month, the Park fire quickly exploded after an alleged arsonist sparked by the blaze in a city park by pushing a burning car into a ravine. The area had baked at temperatures 100F and above for days before and after the fire began. The Park fire has since become the fourth-largest blaze in state history.

The Pacific north-west has also endured intense heat and intense wildfires. Oregon has seen more land burned this year, more than 1.4m acres (567,000 hectares), than any year in the last 32 years, when the north-west interagency coordination center’s record-keeping began.

The extreme heat leads to more intense fires, and makes for challenging conditions for the firefighters responding to the incidents. Firefighters battling the Thompson fire last month, not far from where the Park fire broke out, suffered heat-related injuries.

Heatwaves are increasing in intensity and frequency, as well as duration and range, and are the weather events most directly impacted by the climate crisis, Dr Alexander Gershunov, a research meteorologist with the Scripps Institution of Oceanography, told the Guardian last month. He described heatwaves as “the weather extremes that are impacted by the steroids of climate change”.

“The trend is toward more frequent, more extreme, longer-lasting heatwaves all over the world,” he said. “California is certainly no exception.”