The U.S. Is Still Sweating Out Heat Waves In September. Why?

CREDIT: AP Photo/Nick Ut

Travelers Al Parks, left with his daughter, Markeiba, right, and her 18-month son, Jaden cool off with big fans at Los Angeles Union Station before traveling to Oregon from Los Angeles, Wednesday, Sept. 9, 2015. Temperature reached 99 degrees before noon in downtown Los Angeles.

Labor Day weekend usually means that the U.S. is done with heat waves for the summer. But not this year.

Southern California hit well over 100 degrees Wednesday, putting it easily on its way to a heat wave — which technically means three consecutive days of 90 degrees or more. Citing expected temperatures of 102 to 108 degrees, the National Weather Service put out an “Excessive Heat Warning” Wednesday.

“Maximum temperatures will reach dangerous levels across much of Southern California this week,” it read. “While the afternoon temperatures will present the greatest danger, overnight temperatures will be quite warm as well and will not allow for much relief.”

Wednesday, September 9, was the hottest day of the year in Los Angeles. The air conditioning stopped working in classrooms across the city, stifling students with sometimes 90-degree temperatures inside and sending some to the hospital. Coronado schools announced they would close early for the second straight day on Thursday due to the heat wave.

Heading farther north provided Californians with little relief, as Sacramento faced forecasts of 107 degree highs on Friday. All this heat does not bode well for the massive drought impacting the state, 92 percent of which has been categorized as being in “severe drought” by the U.S. Drought Monitor. California’s four-year-long drought, influenced by climate change, has impacted farm workers, the global food system, and the economy. Wildfires, spurred on by intense drought and heat, have left 17,000 without power — dangerous during a heat wave.

New York City’s Central Park broke a 96-year-old heat record Tuesday, while the rest of the metro region baked under record temperatures as high as 98 degrees, which felt like over 100 degrees with the humidity factored in. The high temperatures are not helping New Jersey, which is struggling with a short recent drought of its own, threatening crops and lawns. South Jersey was categorized as “abnormally dry” by the U.S. Drought Monitor after less than an inch of rain fell in August.

Boston, MA had its first September heat wave in 30 years on Tuesday. Attleboro, MA students returned to school with unseasonably high temperatures, as Tuesday’s high of 96 degrees broke a record for the hottest September day ever measured. Facilities unused to such temperatures during the school year made it difficult for officials keep children from overheating — buildings were only climate-controlled enough to allow students to spend half the day in air-conditioned areas. Nearby Providence, Rhode Island saw its first all-September heat wave in 32 years on Wednesday. Westover, MA hit a record high of 92, and had its first heat wave of the year.

Towns across New Hampshire and Maine hit heat wave status on Wednesday:

Albany, NY hit 90 for the third day in a row as well, making the first heat wave since June 2014, and the third-latest heat wave on record. Dayton, OH had a five-day heat wave over the weekend.

Late, unexpected heat waves aren’t just happening in the United States. The Ukrainian capital of Kiev cancelled school last week due to record high temperatures and smoke from peat bog fires. Istanbul, Turkey saw its hottest September day on record for the month of September Sunday afternoon, hitting 100 degrees in several areas of the city. Temperatures in Israel were set to hit 100 this week even with a massive dust storm blocking much of the sun.

Observational data and climate records make clear that heat waves have already increased in duration and intensity. Climate models have shown that heat waves are “virtually certain” to get worse as greenhouse gases warm the planet. Higher ambient temperatures not just during the summer but the spring and fall, combined with a more intense hydrologic cycle and more frequent blocking patterns suggest heat waves will become worse. This is not news to anyone paying attention to global surface temperature records that continue to fall.

Worldwide, 2015 is well on its way to breaking 2014’s record for hottest year ever measured. July was just the latest month this year to break the all-time record, driven partially by the current El NiƱo but more and more by the underlying trapped heat caused by greenhouse gas pollution.