Climate change is enabling extreme heat to persist longer into autumn, as record-breaking temperatures for October cover much of the western U.S.

An unprecedented late-season heatwave is gripping the West, with October temperature records being broken in major cities, several of which are still experiencing triple-digit temperatures.

On Tuesday, Palm Springs reached 117 degrees Fahrenheit; Phoenix hit 113 degrees, while Tucson reached 105 degrees.

In other parts of California, San Jose set a new daily high at 100 degrees; Oakland reached 96 degrees; Napa hit a daily record at 99 degrees; and downtown San Francisco reached 94 degrees, the hottest October temperature in the city in two years.

Certain regions are anticipated to experience even more intense heat on Wednesday. Heat advisories have been issued across California, Arizona, and Nevada. Excessive heat warnings are also in place for San Francisco, Las Vegas, and Phoenix, while a heat advisory has been issued for Los Angeles.

The geographical area experiencing this exceptional heat is anticipated to extend eastward, encompassing Colorado, where Denver may achieve an unprecedented high of 90 degrees.

If Denver reaches the 90s, it would set a new record for the latest date in the year that the city has ever experienced a temperature that high, according to historical data.

The intense heat wave is forecast to continue through the weekend in much of the Western United States.

Due to the prevailing dry, hot, and windy conditions, fire risk remains elevated from California to Montana.

Climate scientists emphasize that human-induced climate change is escalating the frequency and severity of extreme heat episodes.

The average number of heat waves experienced by major U.S. cities annually has doubled since the 1980s, as revealed by the federal government's Fifth National Climate Assessment , published last November.

The record-breaking temperatures for October observed in Palm Springs and Phoenix on Monday were made at least five times more probable by human-induced climate change, according to Climate Central’s Climate Shift Index .

Global warming is also likely contributing to the extended duration of these extreme heat events, stretching well into the fall months.

An analysis conducted by Climate Central has revealed that fall nights in 212 U.S. cities have experienced an average temperature increase of 2.7 degrees Fahrenheit between 1970 and 2023.

Across the contiguous United States, fall temperatures are rising, with the most pronounced warming occurring in the Southwest, as per an analysis conducted by Climate Central.

' Matthew Glasser contributed to this report.