It wasn’t your imagination. Last year was the hottest ever in the Coachella Valley, according to an analysis of federal data collected in Thermal. The Coachella Valley was the only site in the United States that experienced its highest average temperature in 2018, according to a nonprofit group that crunched data collected by the National Oceanic and Atmospheric Administration. But a warming trend over the past decade continued across the nation.

“So of the 244 cities that we did the analysis on, only one had the hottest year on record, and that was Palm Springs,” said Sean Sublette, a meteorologist with Climate Central, a science and communications group based in Princeton, NJ. “For this particular analysis, we wanted to see when each city had its hottest year on record. We know the planet is warming due to greenhouse gases.”

The Coachella Valley's average annual temperature last year was 76.1 degrees, up from averages of 72 to 73 degrees in the 1950’s. July 23 and 24 were the steamiest days, with the thermometer hitting 122 degrees. Month to month, the area experienced its highest overall heat since 1950, when record-keeping began.

While it can be tough for humans to notice a few degrees difference in temperature, signs of the trend are evident, said longtime Coachella Valley ecologist James Cornett, of JWC Consultants. Until the 1970’s, it was common for there to be snow downtown about once a decade. But the last time snowflakes accumulated on Palm Canyon Drive was in January 1979, he said.

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“It’s clearly getting warmer, there’s no question about it,” said Cornett, who was also director of natural sciences at the former Palm Springs Desert Museum for 30 years. He said joshua trees, teddy bear cholla and other signature desert species are also all but disappearing at hotter and drier lower elevations.

Using NOAA data in the Applied Climate Information System, Climate Central tracks nearly 250 cities representing nearly every weather range and ecosystem in the country, from New York and Los Angeles to smaller sites. The data in the Coachella Valley is collected continuously from a station at Jacqueline Cochran Regional Airport in Thermal that contains thermometers and other instruments measuring wind speed, humidity, sky conditions and other variables.

The stations are typically placed at or near airports because atmospheric information is critical for aircraft conditions, Sublette said. Individual thermometers in a region may register higher temperature spikes, but the airport station offers a steady stream of data. Air traffic controllers and pilots depend on the information to properly estimate necessary distances, for instance. Hotter air is thinner and requires a longer take-off to lift a plane off the ground.

Palm Springs airport data is not as consistent as at nearby Cochran Airport, Sublette said, with numerous gaps in the '80s and '90s, while the data at Cochran offers an accurate long-term climate record. Cornett said he has studied the same federal data sets as those used by the Princeton group, and they were right to use the Thermal airport measurements because they are more consistent, although Palm Springs’ can be helpful for information before 1950.

Other infrastructure can also be affected by extreme heat. “Rail lines buckle once you have temperature in excess of 115 degrees, and even sidewalks can get soft,” said Sublette. Electric grids are taxed as air conditioners are cranked higher, meaning more greenhouse gas emissions that are causing the warming are emitted. Seniors, children and people with chronic illnesses or working outdoors also face increased health risks.

“It all adds up,” said Sublette.

Across the nation, the West coast and Southeast continued to experience near-record high average temperatures, the analysis found. The Northeast region experienced unusually large rainfall, which kept temperatures at about what they were in the last few years. Only isolated areas in the Great Plains saw slightly cooler temperatures.

As for Palm Springs, “obviously you’re in a much more arid climate, so you don’t have the heat and humidity issue. But heat is still heat,” said Sublette. “When people say, ‘oh it’s a dry heat,’ I say ‘oh, you mean like an oven?’”

A series of United Nations scientific reports have identified human-caused global warming as a major threat, including one last fall that warned if drastic action is not taken within the next decade to slash harmful carbon dioxide and other greenhouse gases, then widespread impacts will be unavoidable, including more extreme weather, rising seas and increased public health concerns.