If you’re making plans for outdoor activities Sunday in Las Vegas, check the weather forecast first.

It might be cooler and wetter than normal.

The strongest chances of Southern Nevada receiving any rain during the Labor Day weekend will happen Sunday, said Brian Planz, a meteorologist at the weather service office in Las Vegas.

If it does rain, it won’t be a lot, about 0.25 inches or less, he said. And the high temperature may not top 90 degrees, he said. The average high for early September is in the upper 90s.

However, the rain chances are “not a direct result” of Hurricane Marie, which is spinning well off the southwest Mexico coast and moving northwest.

Planz explained the situation this way: A low-pressure system off the California coast is interacting with a high-pressure system to the east of Las Vegas. Moisture from a very-warm eastern Pacific Ocean will be pulled up between them this weekend, affecting the Southwest.

There’s an “abundant amount” of moisture in that region, he said.

The eastern Pacific has experienced a very active hurricane season so far, with Lowell currently threatening Hawaii. The state got battered by Lala last month.

How much rain falls in the valley, and exactly when, is dependent on a lot of variables, Planz said.

But Las Vegas will not experience a Hilary-type event, he said. In September 2023, a weakened Tropical Storm Hilary soaked the valley and caused flooding in the Spring Mountains and Death Valley National Park.

Planz said Labor Day looks “relatively dry,” with highs in the 90s, and more chances of monsoon storms may emerge next week.

Weak monsoon season

The monsoon season, which began in late June and lasts through September, has been almost nonexistent for the valley during a very dry year.

In August, the airport recorded 0.18 inches of rain, its wettest month since February (0.35). But the August average is 0.32. Reid has registered 0.69 inches of precipitation so far in 2026. The average through late August is 2.64.

Reid saw no measurable rain in July. On June 23, the airport recorded 0.02 inches of rain, breaking a rainless streak of 124 days. It was the only rainfall of the month.

But changes may be on the horizon in September.

The weather service’s Climate Prediction Center said “an unsettled pattern and widespread above-normal precipitation are favored for the West through mid-September. Potential for tropical moisture may produce heavy rainfall for some areas, especially the Southwest.”

The average September precipitation for Las Vegas is 0.32 inches. Last year, the valley recorded 0.28 inches.

Contact Mark Davis at mdavis@reviewjournal.com.