The Impact of El Niño and Climate Change on Record-Breaking Summer Heat

As summer transitions into fall, the heat wave across the country shows no signs of abating. El Niño and climate change have combined forces to bring about record warmth this season, delaying the much-anticipated arrival of pumpkin spice.

According to forecasters at the U.S. Climate Prediction Center, the likelihood of warmer-than-normal temperatures remains high until at least the end of September. Computer models predict a sustained period of unseasonal warmth, particularly in the upper Midwest and Deep South, with temperatures potentially reaching 5 to 10 degrees Fahrenheit above normal in late September.

This summer has already gone down in history as the hottest on record in the U.S., with tens of thousands of heat records shattered across the country. Tens of thousands of daytime maximum temperature records and nighttime minimum temperature records have been broken since the beginning of 2026, outnumbering cold records by a significant margin.

The persistence of this heat wave into September has caught many areas off guard, with even traditionally cooler regions experiencing extreme temperatures. Southern California, for instance, saw unprecedented heat warnings well into the second week of September, making places like Rodeo Drive feel more like Bourbon Street.

Exploring the Causes of Autumn Heat

The primary driver behind these heat waves is unequivocally climate change. Rising average temperatures have elevated the threshold for extreme heat, leading to more humid and intolerable conditions during very hot days and nights.

The increasing frequency of heatwaves can be attributed to shifting upper-level patterns favoring extreme heat events, exacerbated by a lack of mitigation measures. The intensification of high pressure systems in the atmosphere results in heat domes, causing compressed air to heat up significantly when combined with sunlight and dry soil.

Predicting the End of the Heat Wave

While temperatures may not reach the extremes seen in July, many regions are expected to endure summer-like heat well into the remaining days of September. The looming presence of El Niño further complicates the situation, with its influence on global weather patterns likely to persist in the coming months.

Historically, strong El Niños have been associated with warmer-than-normal temperatures across the United States, suggesting that the trend of breaking heat records may continue throughout the fall and winter seasons.