Summer heat wave tracker: July was the hottest month ever recorded, by a lot

• Extreme heat waves are a defining part of summers across the globe now.
• As global temperatures rise, heat waves are becoming more common, severe, and long-lasting.

Summer is not what it used to be. Extreme heat is becoming more frequent, severe, and long-lasting, with less overnight relief as nighttime temperatures also rise.

It's now common for multiple disastrous heat waves to batter different parts of the planet at the same time, fueling droughts and wildfires.

That's because of the climate crisis: Human activities have released so much heat-trapping carbon dioxide and methane into the atmosphere that average global temperatures are rising. All over the planet, it's becoming hard to ignore.

So far, this summer has brought the hottest day, week, and month in recorded history. Deadly heat waves have pummeled the US, Mexico, Europe, the Mediterranean, North Africa and the Middle East, China, Siberia, South Asia, and even South America where it's winter.

See for yourself how rising temperatures are battering the planet. Here's the latest extreme-heat news of 2023.

July was the hottest month on record, ever, by a wide margin

NASA announced dire news on Monday: No month in recorded history, dating back to 1880, has ever been as hot as this July.

July 2023 didn't just break the record. It blew past it.

"The difference between 2023 and 2019, which was the previous record, was hugely significant," Gavin Schmidt, climate modeler and director of the NASA Goddard Institute for Space Studies, said in a live panel announcing the finding.

The return of El Niño weather pattern, which warms the tropical Pacific Ocean, may have played a small role this year, but "the long term trends that we're seeing are all due to human activity," Schmidt said.

NASA scientists said drastic measures must be taken in order to plateau these trends and stop global temperatures from continuing to rise.

Without action, "in the longer term, we are going to continue breaking these records as we continue to emit greenhouse gases," Schmidt urged.

Phoenix finishes a 31-day streak of breaching 110 degrees Fahrenheit

The July heat in Phoenix, Arizona was so bad that doctors at the local burn center reported being inundated with people who sustained severe burns from touching pavement.

For 31 days straight, every day reached a high of 110 degrees or more. The streak finally broke on July 31, the AP reported, when airport thermometers topped out at 108 degrees.

The hottest day in the world

Preliminary data indicate that Earth's average temperature hit an all-time record high on July 3 and then broke that record for the two following consecutive days, according to AP.

This data comes from the University of Maine's Climate Reanalyzer, which measures air temperature 6.5 feet (2 meters) above Earth's surface at random points worldwide, and combines them to calculate an overall average, global temp.

The figures are not an official record since the National Oceanic and Atmospheric Administration "cannot validate the methodology or conclusion of the University of Maine analysis," NOAA told NBC 5 Dallas-Fort Worth.

That said, "This is showing us an indication of where we are right now," NOAA chief scientist Sarah Kapnick told AP.

The global average on July 3 reached a record 62.62 degrees Fahrenheit (17.01 degrees Celsius) and then surpassed that on July 4, climbing to 63 degrees Fahrenheit (17.23 degrees Celsius) and sustaining that temp. through Thursday, per AP.

A combination of factors, including summer weather, a warmer atmosphere, and seasonal weather patterns like El Niño have gotten us to this point. But experts warn that it could still be getting hotter.

The hottest day is, "going to be when global warming, El Niño and the annual cycle all line up together. Which is the next couple months," said Myles Allen, a professor of geosystem science at Oxford University, told The Washington Post.

The sea around the UK and Ireland is much warmer than experts expected

In June, sea temperatures reached an "unheard of" 41 degrees Fahrenheit (5 degrees Celsius) above normal around the United Kingdom.

This represents an extreme category four marine heatwave, as defined by the National Oceanic and Atmospheric Administration.

And it poses serious harm to marine plants and animal life. For example, the category four heatwave that struck Western Australia in Feb. 2011 lasted 66 days and caused the extinction of two types of local seaweed and depleted blue crab and bay scallop populations.

"Current temperatures are way too high but not yet lethal for majority of species, although stressful for many … If it carries on through summer we could see mass mortality of kelp, seagrass, fish and oysters," in the UK, Dan Smale, an ecologist with the Marine Biological Association, told the Guardian.

Smale said that this region of the Atlantic usually isn't affected by rising sea temperatures since they typically have cool waters. So these developments are surprising and concerning to researchers in the area.

These marine heat waves are likely to increase in frequency because of climate change, according to a 2019 study in Nature.

Arctic regions are reporting record temperatures, threatening permafrost thaw

Since early June, Siberia has been experiencing a dire heat wave, with temperatures regularly climbing above 100 degrees Fahrenheit (38 degrees Celsius). In past years the average temperature in June was around 74 degrees Fahrenheit (23 degrees Celsius).

These record-setting temperatures pose a risk to the region's permafrost, a permanently frozen layer of soil that holds huge amounts of trapped carbon dioxide and methane, according to a Arctic Risk Platform report.

This is a problem because as permafrost thaws it releases these potent greenhouse gasses into the atmosphere, which will in-turn make the planet even warmer, Sergey Zimov, a geophysicist and ecologist, told Unesco.

Similar concerns have been forecasted for other arctic regions that contain vast swaths of permafrost like Greenland.

"These heat waves have major implications for people and nature and will continue to happen more frequently unless we rapidly cut emissions of greenhouse gasses," Samantha Burgess, deputy director of the European Union's Copernicus Climate Change Service, told CNN.

New York City and Boston were engulfed in unhealthy smoke wafting from unseasonable Canadian wildfires

New Yorkers looked up to an orange sky on June 6, as smoke was coming off of raging Canadian wildfires that drifted across the Northeastern US, causing concern about air quality.

Air quality alerts were issued all the way down to the Carolinas and as far west as Minnesota, per The New York Times. North Carolina issued a Code Red air quality alert for countries across the state and maintained it through June 7.

Canada is battling hundreds of wildfires that are hitting both sides of the country at the same time, an "unusual" occurrence for this time of year, Michael Norton, an official with Canada's Natural Resources ministry, told Reuters.

"At this time of the year, fires usually occur only on one side of the country at a time, most often that being in the west," he said.

The fires follow record-breaking temperatures battering the country's northwest in May (see below). Persistent droughts seen across the country are precipitating the wildfires, which have already burned an area about 1200% larger than normal this year.

"If this rate continues, we could hit record levels for area burned this year," Norton told Reuters.

Summer outlook for the US: hotter than average

Extreme heat may define this summer in the US, according to modeling by the Climate Prediction Center of the National Weather Service released May 18.

Their three-month outlook, in the map below, shows above-average temperatures across most of the states through August:

An early-season heat dome baked the Pacific Northwest

Four locations in the Seattle region set temperature records on May 13. Quillayute reached 90 degrees Fahrenheit, which is 10 degrees higher than its 1975 record, The New York Times reported.

Canada is also feeling the effects of the heat dome. Alberta is fighting 92 wildfires, almost a third of which were labeled "out of control" as of May 18, according to the Alberta Wildfire Status Dashboard. Around 19,500 people had to evacuate their homes as of May 16, CBC news reported.

The smoke from those fires rolled across the central US that weekend, triggering air quality alerts and darkening skies from Seattle to St. Louis.

The region's historic June 2021 heat wave is still fresh on residents' minds. Studies estimate that the event killed almost 800 people.

Michael Wehner, a climate scientist at Lawrence Berkeley National Laboratory, told Axios that it's unusual for the same region to have two extreme heat events happen in such short succession.

"I realize that the two events are completely independent, but it is still a surprise," he told Axios.

Back-to-back heat waves menaced China's power grid

Heat advisories were issued across China as Beijing was expected to swelter to 36 degrees Celsius (97 degrees Fahrenheit) on Monday, Reuters reported on May 15.

China's usually moderate-climate area Yunnan has already recorded heat up to 40 degrees Celsius (104 degrees Fahrenheit), putting pressure on the local power grid as millions turned to their air conditioners for relief.

The heat waves are hitting China earlier in the season than usual, which could be damaging to crops and lead to food shortages. That could exacerbate inflation in a country that's still recovering from its three-year strict zero-COVID-19 policy, Reuters reported.

An incoming El Niño could turn up the heat

An El Niño effect could exacerbate this summer's heat.

The El Niño Southern Oscillation (ENSO) is a recurring climate cycle that has a major impact on global weather patterns year-to-year. It alternates between a cool phase, called La Niña, and a warm phase, called El Niño.

The National Oceanic and Atmospheric Administration just declared the end of an almost two-year cool phase in March.

You can see in the animation below that warm water is starting to replace the cool water in the tropical Pacific, traveling East to West. That indicates El Niño is coming, pushing warm water and warm weather toward the Americas.

El Niño will likely emerge in the coming months and last until winter, according to a NOAA blog published May 11.

Though every ENSO cycle is different, El Niño tends to increase global temperatures an average of 0.2 degrees Celsius (0.36 degrees Fahrenheit), the BBC reported.

It's not just the tropical Pacific that's warming up. The map below shows how oceans worldwide hit record-high temperatures in April:

Scientists sounded alarm bells as the average global ocean temperature hit 21.1 degrees Celsius (70 degrees Fahrenheit), which is 0.1 degrees Celsius higher than the previous 2016 record, according to a news update from the scientific journal Nature.

Horses collapsed amid Spain's scorching April temperatures

Temperatures surpassed 100 degrees Fahrenheit in Spain multiple times that month. According to The Guardian, the airport in Córdoba reported the highest April temperature ever recorded in Europe: 38.7 Celsius, which is nearly 102 Fahrenheit.

Reuters reported that two horses collapsed — one of them dying — with symptoms of dehydration while pulling passenger carriages in Seville. In Catalonia, an irrigation canal serving 50,000 hectares of farmland closed because there wasn't enough water.

Deadly humid heat swept South Asia

The last two weeks of April broke temperature records across Bangladesh, India, Thailand, and Laos.

In large regions of South Asia in April, the heat index exceeded the "dangerous" threshold of 41 degrees Celsius (105.8 degrees Fahrenheit) and, in some areas, approached the "extremely dangerous" 54 degrees Celsius, where the human body struggles to maintain its temperature, according to World Weather Attribution.

Vietnam broke the record for its hottest day on May 6th, with a blistering temperature of 111.3 degrees Fahrenheit (44.1 degrees Celsius), according to the BBC.

The extreme early-season heat brought a sudden spike in heat stroke cases, a surge in electricity demand, melting roads, early schools closures, and over a dozen deaths reported in India and Thailand.

High humidity made the heat wave much more dangerous. That's because humid air can inhibit the human body's main cooling mechanism: the evaporation of sweat. That's why heat index — a proxy for how hot it really feels — factors in humidity and is often higher than the actual temperature.

"The true cost to human lives will only be known months after the event," the organization wrote in a press release.

Climate change made that heatwave 30% more likely, according to a study by World Weather Attribution, a renowned organization of scientists that uses peer-reviewed methods to do rapid assessments of extreme weather events.

This post has been updated with new information. It was originally published on May 19, 2023.