October heat wave brings scorching temperatures to millions in West

A cooler weekend is ahead for the Southwest after a late-summer scorcher has brought record-setting temperatures above 100 degrees in cities like Los Angeles and San Diego.

These warmer than average temperatures could have serious health impacts for several more days, especially for parts of Southern California, where warm lows will make it hard to cool down overnight.

The culprit behind this October heat wave is a persistent area of high pressure, known as a heat dome, that is sitting over the West.

(MORE: What is a heat dome?)

Here's what you need to know to stay safe.

Through Friday: Record-breaking heat

Temperatures are running 15-20 degrees above average for much of the region, with parts of Southern California and the Southwest seeing multiple days in the upper-90s and triple digits.

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Low temperatures will linger in the low- to mid-70s in places like Los Angeles and San Diego, bringing little to no relief overnight.

The heat will continue to spread north and east over the next couple of days, bringing widespread 80s and 90s to parts of the Rockies and Northern Plains.

Dozens of record highs and warm lows could be broken throughout this week, from Southern California up to Washington and Montana. California's Central Valley will be especially prone to record heat this week.

Some places will see overnight low temperatures that look more like what you would typically see for a high this time of year.

This heat wave will bring dangerous conditions, especially for those susceptible to heat-related illnesses. You should continue to monitor your forecast closely and change your plans accordingly.

(MORE: Heat safety & prep)

Extreme heat warnings are in effect for much of coastal Southern California through at least Thursday evening, which means there is a high heat risk even for healthy individuals.

Heat advisories are out for a portion of the central part of the state as well, where temperatures could threaten those sensitive to heat like the elderly, children and those without AC.

(MORE: 5 things to know to stay safe during a heat wave)

Stay inside air-conditioned spaces as much as possible, drink more water than usual, wear lightweight clothing and consider moving any outdoor activities to the early morning or late evening when it's cooler.

(MORE: Heat domes fuel more MLB home runs in 2026)

Coming this weekend: 10-15 degrees cooler

Some relatively cooler air will begin to trickle in from the Northwest late this week and some of that could reach Northern California on Saturday.

Much of California plus the Northwest will see below average temperatures by Sunday. That means 60s and 70s for California, 70s and 80s for the Desert Southwest and 50s and 60s across much of the rest of the West. Lower elevations of Colorado and New Mexico will have to wait a little longer.

(MORE: How El Niño could impact your winter)

Record heat recap

Downtown Los Angeles has seen four days above 100 this month so far. This has only happed two other Octobers: 1971 and 1958. These 100 degree days are all in a row as well, occurring October 2 - 5. The city hasn't seen four consecutive days above 100 degrees in October before, and this ties the fourth longest stretch of consecutive days above 100 degrees.

For Downtown Los Angeles, this has been their hottest June 1 to October 4 of all time.

There were already numerous daily record highs broken across parts of California and Nevada this weekend.

On Saturday, San Diego saw their daily record high broken at 105; as well as Santa Ana, California (107); Newport Beach, California (94); Anaheim, California (105); Oceanside Harbor, California (101); Vista, California (108); Escondido, California (103); Idyllwild, California (92); Oxnard, California (97); Burbank, California (102); Winnemucca Airport, Nevada (90).

On Sunday, many of the sam cities again saw their daily record high broke, including San Diego (100); Anaheim, California (101); Oceanside Harbor, California (98); Ramona, California; Stanley, Idaho (79); Camarillo, California (99); Oxnard, California (99); Burbank, California (101); Elko, Nevada (90); Ely, Nevada (85); Eureka, Nevada (93).

On Monday, numerous records were broken across Southern California: Escondido (106); Santa Ana (106); Anaheim (104); Vista (103); Ramona (101); Chula Vista (99); Woodland Hills (106); Downtown LA (104); Camarillo (99); Oxnard (98).

More records were broken on Tuesday: Anaheim, California (100); Vista, California (101); Chula Vista, California (97); Escondido, California (105); Ramona, California (101); Laramie, Wyoming (78); Rawlins, Wyoming (80); Idaho Falls, Idaho (81); Lake Yellowstone, Wyoming (70); Buffalo, Wyoming (87); Colorado Springs, Colorado (83); Ontario, Oregon (86); Twin Falls, Idaho (82); plus many more.