A summer that began early across the US continues, with warmer-than-normal temperatures expected to persist into autumn. The US Climate Prediction Center forecasts increased odds for above-normal temperatures across much of the country through at least the end of September, influenced by El Niño and climate change. Computer models indicate a pronounced ridge pattern in the atmosphere, which can sustain warmer conditions. The Upper Midwest and the Deep South are projected to experience temperatures 5 to 10 degrees Fahrenheit above normal in the latter half of September.
This summer has been the hottest on record in the US, with nearly 44,000 record daytime highs and over 53,000 record-high overnight minimum temperatures recorded at weather stations nationwide. Since the beginning of 2026, thousands of monthly and all-time heat records have been broken, while only about 21,500 low-temperature records have been set. Notable records include Salt Lake City reaching 109 degrees Fahrenheit on July 12, and Washington, DC tying its warmest overnight low of 84 degrees Fahrenheit on July 3.
Despite the arrival of September, heat warnings have been issued in areas typically less affected by heat waves, including Southern California. Climate change is identified as the primary driver of the extreme heat, raising average temperatures and increasing the severity of hot days. The increase in overnight temperatures has also been significant, contributing to the dangers of heat waves, as the lack of nighttime cooling exacerbates heat stress.
The warming climate alters upper-level atmospheric patterns, making extreme heat events more common. While temperatures for the remainder of September may not reach the extremes of July, many areas will still experience summer-like heat. El Niño, characterized by warmer-than-normal Pacific Ocean waters, is expected to influence weather patterns, particularly in the colder months. This year's El Niño is anticipated to be record-setting, suggesting continued warmer-than-normal temperatures across a large portion of the US through the fall and winter, indicating that heat records may continue to be broken this year.