HOUSTON, July 22 (Xinhua) -- Five cooling centers were opened Sunday afternoon in Houston, U.S. state of Texas, for residents who don't have access to air-conditioned buildings.

Officials urged high-risk groups, such as adults over 55-year-old, children under 5 and residents with chronic illness to seek shelter inside air-conditioned buildings during the hottest part of the day.

Temperatures on Sunday are expected to peak between 100 and 103 degrees Fahrenheit (about 37.7 and 39.4 degrees Celsius).

Residents are also urged to drink plenty of water, take frequent cool showers or baths, and wear light-colored and loose-fitting clothing.

Mayor of Houston Sylvester Turner on Sunday reminded residents of not leaving children or elderly in vehicles during the heat.

On Thursday, a 3-year-old child died after he was left inside of a daycare van. According to local police, the boy was left in the vehicle for at least four hours. Temperatures inside reached at least 113 degrees Fahrenheit (45 degrees Celsius).

The city's effort came as the National Weather Service (NWS) issued its third heat advisory in as many days. A Heat Advisory will remain in effect for the southeastern part of Texas, including the Houston area, during the hot hours of the day through Monday.

According to the NWS on Sunday, dangerous heat remains in place across the southern Plains, lower Mississippi Valley, and much of the Southwest and far western United States. This heat is expected to remain in place through Monday across the southern Plains and Lower Mississippi Valley, and through at least mid-week for the Southwest and much of the western coast.

Excessive heat watches, warnings and heat advisories are currently in place across these regions. by Tuesday, the Desert Southwest will see temperatures climb well above 110 degrees Fahrenheit (over 43.3 degrees Celsius).