Warning: Excessive heat arrives

The National Weather Service has issued an excessive heat warning for today in Southern Nevada, where temperatures are expected to reach 112.

Forecasts call for high temperatures through Thursday, but meteorologists say thunderstorms will dampen conditions for the weekend. A surge of moisture expected to move from the southeast could arrive anytime through Monday, said Stan Szyzyk, weather service meteorologist.

Winds are expected to be light today.

Medical officials are on alert for heat-related illnesses and are advising residents to avoid strenuous outdoor activity during the heat spell.

Gretchen Papez, spokeswoman for Valley Hospital, said about 10 percent of the patients the hospital has seen in the past two weeks have heat-related issues.

Crews at University Medical Center and Sunrise Hospital also have seen an increase in patients with heat symptoms.

Similar advisories are in effect in parts of California and Arizona, which could pose a challenge for crews battling lingering wildfires.

In Southern Nevada, two records were set last week for warmest lows. July 4 saw a low temperature of 88 degrees; July 5's was 87. Temperatures have reached 110 degrees several times this year, but the weather service said heat warnings of this magnitude haven't been issued yet.