Summer heat wave tracker: New York City bathed in wildfire smoke drifting down from Canada

• 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. heat waves are becoming more frequent, severe, and long-lasting, with less overnight relief as nighttime temperatures also rise.

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

Disastrous heat waves pummeled almost every part of the globe over and over again last year, 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. Forecasts show 2023 may bring another exceptionally hot summer.

Already this year, a heat dome broke records across the Pacific Northwest. Smoke from hundreds of wildfires in Canada drifted all the way to New York City and Boston. Meanwhile, deadly heat waves have struck China and South Asia.

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

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 bakes 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 menace 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 collapse 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 sweeps 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.

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.