June Was Earth’s Hottest on Record. August May Bring More of the Same.

The News

Last month was the planet’s warmest June since global temperature record-keeping began in 1850, the National Oceanic and Atmospheric Administration said in its monthly climate update on Thursday. The agency also predicts unusually hot temperatures will occur in most of the United States, almost everywhere except the northern Great Plains, during August.

The first two weeks of July were also likely the Earth’s warmest on human record, for any time of year, according to the European Union’s Copernicus Climate Change Service.

Why It Matters: Many places have suffered sweltering heat and humidity.

Many daily temperature records were set in June across the Southern United States, particularly in Texas and Louisiana. Temperatures in Laredo, Texas, reached 100 degrees on more than 20 days in June. Austin, El Paso and San Antonio reached triple digits on more than 10 days each. The heat index, which also accounts for humidity, was well past 100 much of the time in all of these cities.

Extreme heat can be dangerous for anyone’s body, but older people and outdoor workers are at particular risk. Summer heat waves in Europe last year may have killed 61,000 people across the continent, according to a recent study.

This year’s heat and humidity have been devastating in northern Mexico, where more than 100 people have died of heat-related causes, according to reports from the federal health ministry.

Background: A heat dome parked over northern Mexico, made worse by climate change.

Heat domes are weather phenomena that form naturally from time to time. Some meteorologists and climate scientists believe that a warming Arctic is causing the jet stream to slow down, meaning weather systems stay longer in one place. John Nielsen-Gammon, director of the Southern Regional Climate Center, said it’s too soon to know whether this happened with the June heat dome specifically.

Other scientists have suggested that last month’s heat wave was made five times as likely and 5 degrees Fahrenheit hotter than it would have been without climate change.

Although heat waves happen naturally, the sheer heights of June’s temperatures around the globe were very unlikely without climate change, said Dr. Nielsen-Gammon.

What’s Next: More abnormal heat across most of the United States.

There’s currently another heat wave over a huge swath of the country, and it is more diffuse.

More than a quarter of the U.S. population experienced dangerous heat on Thursday, according to a New York Times analysis of daily weather and population data. Phoenix has baked at more than 110 degrees Fahrenheit for at least 19 days in a row.

The Atlantic Ocean and parts of the Pacific are both abnormally warm right now because of the natural El Niño climate pattern in the Pacific and also because of human-caused climate change. About 40 percent of the planet is experiencing a “marine heat wave,” NOAA scientists previously said last week, warning that coral reefs are at risk of bleaching and dying.

Sea surface temperatures in the Atlantic, particularly off the coast of Africa, have been “well above normal” for the past month, said Matt Rosencrans, a meteorologist at NOAA’s Climate Prediction Center. “That is quite the interesting dynamic to have both the Pacific and the Atlantic Ocean basins so anomalously warm at the same time.”