Rachel's remnants will trigger flooding rain and strong winds well inland across the Desert Southwest, including cities like Las Vegas.

That's not all. We'll see heavy snow in parts of the northern Rockies and Major Hurricane Simon is poised to rake southwest Mexico, including Puerto Vallarta.

First, Rachel

Potential impacts

Weather in your inbox

Forecast Location

Sign Up

By signing up you agree to the Terms & Privacy Policy. Unsubscribe at any time.

High winds

Rachel's remnants could produce gusty winds through much of the Desert Southwest through Monday morning, particularly over higher elevations of Arizona, Nevada and Utah.

These winds could lead to some tree damage, blowing dust and power outages.

Get More of Our News on Google

Set The Weather Company as a 'Preferred Source' to get quicker access to the news you value.

Flash flooding

As the remnant moisture and upper-level spin from Rachel moves into the Southwest, heavy rain could bring flash flooding across the region, including Southern California, lingering into Monday or Tuesday.

Widespread rain totals of 1 to 5 inches are expected with locally higher amounts possible.

This could lead to flash flooding of normally dry creeks, arroyos, slot canyons and urban areas, including parts of the L.A. Basin, San Diego metro, Las Vegas and Salt Lake City.

If you had plans for any of the national parks in the Southwest, we would suggest canceling those plans until Wednesday, given the threat of both flash flooding and thunderstorms.

(MORE: What to do before, during and after a flood)

Wait – is that snow on the map?

Yes, as the moisture from Rachel meets colder air from a front moving in from the Northwest, snow could accumulate in parts of the Sierra Nevada as well as the Rocky Mountains.

Parts of Wyoming, Montana and Idaho could see their first significant snow of the season, with some places forecast to get over a foot.

(MORE: The West's best shot at snowpack recovery is from El Niño)

Much-needed heat relief

As that front collides with the tropical moisture, it will also bring a long-awaited cooldown to parts of the Southwest, including Los Angeles.

After being stuck in the 90s and triple digits for over a week, temperatures will drop 5 to 15 degrees below average for much of the region by Monday.

Highs will be in the upper 60s and 70s for Southern California, while parts of Arizona and New Mexico will drop into the 70s and 80s.

Major Hurricane Simon

As all this is happening, a powerhouse hurricane is taking aim on southwestern Mexico.

Hurricane Simon is brushing along Mexico's coast at Category 4 intensity.

A Hurricane warning is in effect from Punta San Telmo to El Roblito along with Las Islas Marias.

Damaging winds and flooding rain are both likely along and near the track of Simon in southwest Mexico. Up to 30 inches of rain could lead to dangerous landslides in hilly or mountainous terrain.

This could be the strongest, most damaging hurricane to affect Puerto Vallarta in three years, since Hurricane Lidia downed numerous trees, damaged roofs and triggered landslides in and around the city in October 2023.

Some of Simon's remnant moisture could stream into the central U.S., giving a boost to locally heavy rain and thunderstorms Tuesday into Wednesday.

(MORE: What a historic El Niño means for your fall and winter)

SoCal's first tropical storm watch since 2023

As Rachel was approaching the California coast, SoCal was issued its first tropical storm watch since the remnant of former Hurricane Hilary moved into the state in 2023. (Note: While a Southern California tropical storm watch was issued in 2023, Hilary was not a tropical storm when its remnant moved over Southern California, according to a National Hurricane Center post-storm analysis.)

Caitlin Kaiser graduated from the Georgia Institute of Technology with both an undergraduate and graduate degree in Earth and Atmospheric Sciences before starting her career as a digital meteorologist with weather.com.