The Hottest June Ever Recorded in California Was Like a Permanent Suana

Written by Kristin Hitchcock
Updated: June 13, 2023
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According to Daniel Swain, a researcher with the UCLA Institute of the Environment and Sustainability, June 2021 was California’s hottest June on record. The average temperature of this June was 6.8 degrees above the average, which is based on the recorded temperatures from 1901 to 2000.

With that said, different places in California did experience different temperatures during this month. It’s just that the average was higher than usual across the whole state. For instance, San Bernardino County had an average temperature of 87.3°F in June, while Death Valley National Park had an average temperature of 102.8°F.

What really surprised me about the Death Valley National Park average is that it includes both nighttime and daytime temperatures. That means the days likely got much hotter than 102.8°F.

Abandoned, Absence, Building Exterior, Built Structure, California

Death Valley National Park had an average temperature of 102.8°F.


What Are Other Notable Heatwaves?

Heatwaves aren’t all that rare in California, though they are still considered abnormal. California has experienced several heat waves throughout history, some of which have been deadly.

Here’s a list of notable heatwaves:

  • 1913 – In July, the hottest heatwave ever struck California. During this July, Death Valley reached its record high temperature of 134°F at Furnace Creek (which really lived up to its name that day). Today, that still remains the hottest ambient air temperature ever recorded on Earth.
  • 2006 – In July and August, California experienced one of the longest heatwaves in its history. This prolonged heatwave affected California and other states around it for nearly two months, causing over 140 deaths and widespread power outages. This heatwave was caused by a strong high-pressure system that blocked airflow from the Pacific Ocean.
  • 2017 – In June and July, several heatwaves hit California and surrounding states. During this time, several daily and monthly records were broken.
  • 2020 – In August and September, California had a series of later-than-usual heatwaves. These coincided with dry lightning storms and wildfires, which were difficult to control. Death Valley almost made a new record, reaching 130°F on August 16. Los Angeles County did reach a new record of 121°F at Woodland Hills on September 6.
  • 2022 – Recently, in 2022, an intense heatwave broke out across Southern California in September. The hot conditions helped start and sustain several wildfires in the region.

Why Did It Get So Hot?

There are many contributing factors to every heatwave, and the one that happened in June 2021 was no different.

However, the primary reason was a dome of hot air traveling across the western United States. This dome caused temperatures to skyrocket across the western United States, breaking records all over the place.

This was one of the more severe heat waves of the year throughout the United States. Plus, it was also one of the earliest on record. Most heatwaves in California occur between July and September.

The heatwave heightened the existing drought. Many people were concerned with fires, but no major ones broke up.

Here is a roundup of records that were broken in the state:

  • Palm Springs: 123°F
  • Sacramento: 109°F
  • Woodland Hills: 109°F
  • Death Valley: 128°F, which was the highest temperature ever measured on Earth in June
A dramatic south-looking view of Stevens Creek reservoir in California during a drought

Water evaporates faster at higher temperatures, and people


more water at higher temperatures. It’s a lose-lose situation.

©Jake Osborne/

How Were People Impacted?

Besides being hot and miserable, the heatwave also caused many other impacts on the local populations.

Health Risks

High temperatures can increase the odds of certain illnesses, especially in vulnerable groups like seniors and children. Outdoor workers and those with chronic conditions are also at risk for heat-related illnesses.

According to the CDC, there were 3,504 heat-related emergencies in California from June 11 to July 4, 2021 (when this heatwave occurred). It was reported that nearly 1,000 people died in the state due to the heat.

Power Outages

The heat wave strained the state’s power grid. Many people turned on their air conditioners and fans to cope with the heat, but the state’s power system couldn’t handle the load. The California Independent System Operator had to issue several Flex Alerts urging customers to conserve energy.

Sadly, some power outages did occur in parts of the state. In the end, thousands of customers were affected.

Water Shortages

Water evaporates faster at higher temperatures, and people need more water at higher temperatures. It’s a lose-lose situation.

California was already experiencing a severe drought that had gripped the state for months. The heatwave only worsened that, reducing the water supply for millions of people and farmers.

Many areas were forced to restrict their water due to state regulations or voluntarily. Usually, this involved limiting outdoor watering and washing cars. Some rural areas ran out of water and relied on bottled water deliveries.

Relief Efforts

There were several relief efforts in the area to help people cope with the excessive heat. Some counties opened cooling centers where people could escape the heat and access water.

Some utilities assisted low-income customers facing very high bills due to the heat. Nonprofits also distributed fans and water bottles.

Infrastructure Effects

On top of affecting people, the heatwave also affected the state’s infrastructure.

As we’ve stated, several power outages did occur. Mostly, this was caused by the mass use of air conditioners to cope with the heat. Some power outages did occur, affecting thousands of customers. Governor Gavin Newsom had to sign an emergency proclamation to free up the use of backup power generation.

The heat also caused damage to roads and rail infrastructure. At very high temperatures, roads can crack, and that’s exactly what happened. For instance, a section of Highway 99 near Sacramento had to be repaired after the pavement buckled due to the heat.

The Bay Area Rapid Transit had to reduce its train speeds by ten mph to prevent heat-related damage to tracks. While that might not seem like a lot, it significantly affected route times.

Some of the roads in Death Valley literally melted.

The high temperatures even caused some buildings to break. For instance, a fire station in Stockton had to be evacuated because its roof collapsed due to the heat.

Sign posted in a shop window: Shop closed, no electricity. Energy crisis, blackouts concept.

Some power outages did occur, affecting thousands of customers.

©pamela ranya/

How Were Plants and Animals Affected?

Animals and plants do not have air conditioners. Therefore, they are seriously impacted by heat waves like the one that occurred in June 2021.

The heatwave killed and displaced many animals. For instance, in high temperatures, thousands of clams, mussels, and other marine animals were cooked (literally) on the shores of Bodega Bay. Many salmon were also killed due to lower river flows and warm water.

Many birds and other animals suffered from heat exhaustion and dehydration.

Crops also weren’t made to withstand the high temperatures. The heatwave also caused the drought to worsen, reducing the water available to farms. Many farmers had to reduce their irrigation, thin orchards, or leave some fields empty.

The heat also affected the quality of crops that did make it, including strawberries and lettuce.

Heat always increases the risk of wildfires in the state. Very dry vegetation and hot winds create favorable conditions for igniting a fire and helping it spread. Some wildfires did break out in the state, such as the Lava Fire and Salt Fire in Northern California. Luckily, neither of these was as bad as some people feared.

Still, the smoke from these fires worsened air quality and destroyed visibility in some areas.

Forest Fire, California, 2020, Fire - Natural Phenomenon, Smoke - Physical Structure

Very dry vegetation and hot winds create favorable conditions for igniting a fire and helping it spread.


What Did We Learn?

The heatwave taught state officials and residents in California a few new things about coping with extra heat.

In April 2022, the state released the Extreme Heat Action Plan, which outlines a comprehensive set of actions the state can take to adapt and strengthen its resistance to extreme heat. Many of the things in this plan were learned during the 2021 heatwave.

The plan includes increasing public awareness and notification of the risks of heat. It recommends providing timely information to high-risk communities, for instance.

The state has also taken steps to increase its energy capacity, which (hopefully) helps the state avoid power outages in the future. Several campaigns centering on reducing energy use have also been launched, including the “Flex Your Power” campaign, encouraging residents to reduce their nightly power usage.

California has also recognized the need to implement urban cooling measures. Urban areas often attract heat due to the lack of greenery. To counteract this, California is considering planting more trees, creating green spaces, installing cool roofs and pavements, and increasing water features. These measures may reduce the heat held on by these urban areas.

Finally, California has also invested in community services and response efforts to reduce the health consequences of extreme heat. For instance, the state has helped fund local initiatives and increased heat illness prevention requirements for workers.

The photo featured at the top of this post is © Katrina Brown/

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About the Author

Kristin is a writer at A-Z Animals primarily covering dogs, cats, fish, and other pets. She has been an animal writer for seven years, writing for top publications on everything from chinchilla cancer to the rise of designer dogs. She currently lives in Tennessee with her cat, dogs, and two children. When she isn't writing about pets, she enjoys hiking and crocheting.

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