More than 35 million people are under heat alerts on Sunday afternoon as a dangerous multi-day October heat wave continues across nearly all of California.Temperatures are expected to soar up to 20 degrees above normal for this time of year, into the 90s and 100s, from Northern California, including the San Francisco Bay Area, to the Mexico border.Anadolu via Getty Images - PHOTO: People flock to Baker Beach near the Golden Gate Bridge as a heat advisory is issued in San Francisco, California, October 3, 2026. In some areas of California, especially urban areas, warm nights will provide little to no relief.Los Angeles and San Diego remain under an extreme heat warning, with heat advisories posted on Sunday for San Francisco and Sacramento.ABC News - PHOTO: The high-temperature forecast for California, October 4, 2026.Temperatures Sunday afternoon once again soared into the 90s across much of California, with some areas surpassing 100 degrees.High temperatures on Sunday afternoon will be near 104 in downtown Los Angeles, 103 in Bakersfield, and will climb well into the 90s in San Diego and Sacramento.ABC News - PHOTO: Afternoon temperatures, October 4, 2026, are expected to top 100 degrees in multiple Southern California cities. The extreme heat warnings in Southern California will remain in effect until 8 p.m. local time on Thursday.ABC News - PHOTO: A dangerous heat wave in Southern California is expected to extend into the work week.The heat will expand over much of the West over the next 24 hours, with temperatures running well above average for early October across a large part of the region.Highs on Monday will reach the upper 80s as far north as southern Idaho and Montana, challenging daily record highs in Boise and Billings.ABC News - PHOTO: Tracking the California heat wave through Tuesday, October 6, 2026. It will also be heating up in Denver on Monday, with afternoon temperatures in the upper 80s, potentially challenging a daily record high as well.On Saturday, at least eight Southern California cities broke daily high-temperature marks, including Anaheim and San Diego, which both reached 105 degrees, and Santa Ana, which hit 107 degrees.Southern California under extreme heat warning, increased fire riskMeanwhile, Vista, Calif., north of San Diego, reached a high temperature of 108, breaking a daily temperature record and tying an all-time record high set on June 30, 1985.Rounds of heavy rain across parts of the Gulf Coast and SoutheastFlood watches remain in effect from southeastern Louisiana to southern Georgia, including New Orleans; Mobile, Alabama; Tallahassee, Florida; and Brunswick, Georgia.ABC News - PHOTO: Flash-flood risk through Monday, October 5, 2026, in the Southeast from New Orleans to Jacksonville, Florida.There is a level 2 of 4 risk on Sunday afternoon for excessive rainfall and flash flooding from southeastern Louisiana to the Florida panhandle and up into South Carolina.ABC News - PHOTO: Tracking rainfall in the Southeast from New Orleans to Jacksonville, Florida, through Monday morning. Torrential rain could also trigger potentially significant flash flooding across portions of South Texas on Sunday afternoon and into the evening.The biggest rainfall totals will occur along portions of the northern Gulf Coast, the Florida Panhandle, and from Mobile, Ala., and Biloxi, Miss., to Pensacola and Panama City, Fla., and Brownsville, Texas. In these areas, 2 to 6 inches of rain is forecast, with localized totals of 8-10 inches possible.This article originally appeared on ABC News at https://abcnews.com/US/37-million-people-alert-dangerous-temperatures-october-heat/story?id=136984812