Now playing
01:35
Heat wave breaks records in the West
Larry Pierson, from the Isle of Palms, S.C., purchases bottled water from the Harris Teeter grocery store on the Isle of Palms in preparation for Hurricane Florence at the Isle of Palms S.C., Monday, Sept. 10, 2018. (AP Photo/Mic Smith)
Larry Pierson, from the Isle of Palms, S.C., purchases bottled water from the Harris Teeter grocery store on the Isle of Palms in preparation for Hurricane Florence at the Isle of Palms S.C., Monday, Sept. 10, 2018. (AP Photo/Mic Smith)
PHOTO: Mic Smith/AP
Now playing
00:57
How to prepare for a hurricane
IN SPACE - In this handout photo provided by NASA, Hurricane Patricia is seen from the International Space Station. The hurricane made landfall on the Pacfic coast of Mexico on October 23. (Photo by Scott Kelly/NASA via Getty Images)
IN SPACE - In this handout photo provided by NASA, Hurricane Patricia is seen from the International Space Station. The hurricane made landfall on the Pacfic coast of Mexico on October 23. (Photo by Scott Kelly/NASA via Getty Images)
PHOTO: NASA
Now playing
01:07
Why hurricanes are so hard to predict
PHOTO: Courtesy Amy Lloyd
Now playing
01:06
Why flash floods are so dangerous
Now playing
01:26
Hurricanes: What you don't know
LAS VEGAS, NV - JULY 07:  Lightning strikes during a thunderstorm on July 7, 2015 in Las Vegas, Nevada. The monsoon storm dropped heavy rain and hail in parts of the valley causing street flooding and power outages.  (Photo by Ethan Miller/Getty Images)
LAS VEGAS, NV - JULY 07: Lightning strikes during a thunderstorm on July 7, 2015 in Las Vegas, Nevada. The monsoon storm dropped heavy rain and hail in parts of the valley causing street flooding and power outages. (Photo by Ethan Miller/Getty Images)
PHOTO: Ethan Miller/Getty Images North America/Getty Images
Now playing
01:36
How to protect yourself from lightning
how hurricanes are named orig_00002729.jpg
how hurricanes are named orig_00002729.jpg
Now playing
01:38
How are hurricanes named?
Now playing
01:21
What is a polar vortex?
PHOTO: Franck Verdière/Twitter
Now playing
01:10
What 'rapid intensification' means for storms
A plea for help on a New Orleans rooftop, days after Hurricane Katrina struck the city in 2005.
A plea for help on a New Orleans rooftop, days after Hurricane Katrina struck the city in 2005.
PHOTO: AFP/Getty Images
Now playing
02:14
Top five costliest hurricanes in US history
Storm chasing photographers take photos underneath a rotating supercell storm system in Maxwell, Nebraska on September 3, 2016. Although multiple tornado warnings were issued throughout the area, no funnel cloud touched down. / AFP / Josh Edelson / XGTY
RESTRICTED TO EDITORIAL USE  / MANDATORY CREDIT:  "AFP PHOTO / Josh EDELSON" / NO MARKETING / NO ADVERTISING CAMPAIGNS /  DISTRIBUTED AS A SERVICE TO CLIENTS  ==        (Photo credit should read JOSH EDELSON/AFP/Getty Images)
Storm chasing photographers take photos underneath a rotating supercell storm system in Maxwell, Nebraska on September 3, 2016. Although multiple tornado warnings were issued throughout the area, no funnel cloud touched down. / AFP / Josh Edelson / XGTY RESTRICTED TO EDITORIAL USE / MANDATORY CREDIT: "AFP PHOTO / Josh EDELSON" / NO MARKETING / NO ADVERTISING CAMPAIGNS / DISTRIBUTED AS A SERVICE TO CLIENTS == (Photo credit should read JOSH EDELSON/AFP/Getty Images)
PHOTO: JOSH EDELSON/AFP/AFP/Getty Images
Now playing
00:59
The difference between a tornado watch and a warning
DODGE CITY, KS - MAY 24: A tornado is seen south of Dodge City, Kansas moving north on May 24, 2016 in Dodge City, Kansas. About 30 tornadoes were reported on Tuesday in five different states from Michigan to Texas. Damage to homes and property was also reported in Ford County, Kansas. (Photo by Brian Davidson/Getty Images)
DODGE CITY, KS - MAY 24: A tornado is seen south of Dodge City, Kansas moving north on May 24, 2016 in Dodge City, Kansas. About 30 tornadoes were reported on Tuesday in five different states from Michigan to Texas. Damage to homes and property was also reported in Ford County, Kansas. (Photo by Brian Davidson/Getty Images)
PHOTO: Brian Davidson/Getty Images
Now playing
01:41
How to prepare for severe weather
weather storm chaser convergence nccorig_00010423.jpg
weather storm chaser convergence nccorig_00010423.jpg
Now playing
06:39
Traffic puts tornado chasers' lives in danger
Now playing
01:20
A 'dry' monsoon? They're more common than you think.
ring of fire chad myers weather orig_00003221.jpg
ring of fire chad myers weather orig_00003221.jpg
Now playing
01:13
What is the 'Ring of Fire'?
This picture taken on July 26, 2015 shows a child playing in a fountain on a square to cool himself amid a heatwave in Binzhou, eastern China
This picture taken on July 26, 2015 shows a child playing in a fountain on a square to cool himself amid a heatwave in Binzhou, eastern China's Shandong province. CHINA OUT AFP PHOTO (Photo credit should read STR/AFP/Getty Images)
PHOTO: STR/AFP/AFP/Getty Images
Now playing
01:14
What NOT to do in a heat wave

Story highlights

The heat-related deaths of two elderly people were reported in northern California

Excessive heat warnings have been issued for parts of California, Nevada and Arizona

(CNN) —  

The record-breaking heat roasting the West has killed at least two people.

A 72-year-old man and an 87-year-old woman died Monday in San Jose, California. Their deaths were attributed to the heat, Santa Clara County officials said.

“It is tragic when someone dies of hyperthermia since in most every case it could have been prevented,” Dr. Michelle Jorden of the county’s medical examiner office said in a statement. “Hyperthermia and heat stress happen when a body’s heat-regulation system cannot handle the heat.”

San Jose sweltered in record-breaking, 103-degree weather on Sunday, and the area is under heat advisory until 9 p.m. PT Thursday.

Large swaths of California, Nevada and Arizona are under excessive heat warnings as residents have endured stifling, triple-digit temperatures in the last few days. Parts of eastern Texas and New Mexico are under heat advisories.

In New Mexico, two hikers were found dead earlier this week at Carlsbad Caverns National Park, and heat could have been a factor in their deaths, authorities told CNN affiliate KRIS.

Phoenix burns through the records

For the third day in a row, the heat in Phoenix set new daily records.

The week started with a high of 118 degrees on Monday, then hit 118 degrees on Tuesday and 117 degrees on Wednesday.

Though it has cooled off a few degrees in the Grand Canyon state, it’s still burning hot, with a forecast of 113 degrees for Thursday, according to the National Weather Service.

Crayons melt in Las Vegas

In Las Vegas, which also has seen its share of record-shattering heat, National Weather Service staffers got creative – and conducted an experiment to show just how hot it is.

They eschewed the cliché of frying an egg on the sidewalk and instead left crayons outside in the sun on Wednesday, when the temperature hit 114 degrees. The wax sticks melted into a rainbow sludge of colors.

CNN’s Sonya Hamasaki contributed to this report.