The National Weather Service’s Weather Prediction Center said in a post on Saturday that excessive heat warnings and advisories are in effect throughout much of California, the Desert Southwest and the Deep South.

The post said several cities across the lower Mississippi Valley and Southeast are expected to break their records for daily warmest nighttime lows over the weekend, and the heat wave is bringing the risk of illness with it.

Intense heat has spread across the country, especially in the South, as summer has gotten underway. Texas has had heat waves for three straight weeks, and at least 13 deaths related to the heat have been reported in the state.

Experts said these types of heat waves will become more common in the future and cause additional deaths.

Data from the Centers for Disease Control and Prevention shows that the region of the country made up by Texas, Louisiana, Arkansas, Oklahoma and New Mexico have more than 1,000 emergency department visits associated with heat-related illnesses per 100,000 visits overall on Saturday.

pll/lam/dfm