Chance for thunderstorms in Las Vegas Valley

Temperatures in Las Vegas will cool slightly by the start of next week, but before that there’s a possibility for thunderstorms in the valley, according to the National Weather Service.

An excessive heat warning issued for the valley expired at 8 p.m. Wednesday after the high reached 108, the weather service said. The Colorado River Valley’s excessive heat warning, which covered Laughlin and Bullhead City, Arizona, also expired.

Wednesday also saw brief showers that left trace amounts of rainfall throughout the valley, and there’s a 20 percent chance for rain overnight, meteorologist John Adair said. By 9:30 p.m. a shower was forming between Henderson and Boulder City.

“There’s still a chance that another storm could rumble through tonight,” Adair said.

Rain chances will continue to sit at 20 percent on Thursday, the weather service said.

“Thursday is really the day to watch for rain,” meteorologist Chirs Outler said. “We may have some morning showers with a chance in the afternoon as well.”

Thursday is expected to reach 103 degrees, followed by a high of 104 on Friday and 103 again on Saturday.

A trend toward fall temperatures will come as early as Sunday, Outler said.

“We should finally have highs that are in the mid-90s instead of triple digits,” he said.

Sunday has an expected high of 95, and Monday is expected to reach 96, the weather service said. Overnight lows this week will be right around 80 degrees before dropping to the mid to low 70s early next week.

Last month finished as the second hottest August on record with an average temperature (the daily high and low each day) of 94.3 degrees, just 0.1 degree under the previous August at 94.4 degrees.

The average August temperature for Las Vegas is 90.6 degrees.