Triple-digit heat was recorded Sunday in Dallas for the first time this year.

The temperature broke 100 degrees at the DFW International Airport rising to 101 just before 4 p.m., according to the National Weather Service in Fort Worth.

The weather service also extended its heat advisory for most of North Texas through 8 p.m. Monday as temperatures were expected to remain in the upper 90s and lower 100s. Heat index values were predicted to be as high as 110 during this time.

The weather service’s forecast predicted the Dallas-Fort Worth area to reach a high of 100 Sunday with a heat index of 108 followed by a low around 81. Monday is expected to be hotter with highs reaching 102 and heat indexes rising to 111.

Dallas experiences about 17 triple-digit days a year on average, according to weather service data. The city had 47 days with 100-degree or hotter weather last year — the sixth-most on record. Twenty-one of those days ran consecutively from mid-July to early August.

The metroplex usually records its first 100-degree day on July 1, “so we’re just a little ahead of schedule,” the weather service said in a tweet Sunday afternoon. “Welcome to summer!”

Possible storms Sunday night will make for a hot and humid climate early in the week, a weather service report said.

A weather watch issued Sunday by ERCOT, the state’s power grid operator, indicates there will be a higher demand on the grid than typically expected. The watch is in effect through Friday.

Up to 41 million people in the United States could be exposed to dangerous heat on Sunday, according to a report from The Washington Post. The five hottest cities in the country, the article said, were all in Texas with Fort Worth being the hottest followed by Austin, Dallas, Houston and San Antonio.

Urban heat islands, like some neighborhoods in Dallas, which have fewer trees and more heat-absorbing pavement can be up to 20 degrees hotter than surrounding areas, according to the National Oceanic and Atmospheric Administration.

The latest forecast from NBC5:

MONDAY: Sunny, hot and humid. Low: 82, High: 102

TUESDAY: Sunny, hot and humid. Low: 81, High: 102

WEDNESDAY: Sunny and very hot. Low: 83, High: 105

THURSDAY: Mostly sunny and very hot. Low: 81, High: 103

FRIDAY: Partly cloudy, hot and humid. Low: 80, High: 100