Arriving just in time for Sunday’s equinox, autumn is spreading across the West, Rockies and Southwest.

The system driving the change is an upper-level system moving across the Southwest today and into the southern Rockies tonight. As seen on the WeatherRadar, the system will produce showers and a few thunderstorms across the Southwest and Rockies. Wet snow will be possible over the Continental Divide.

Big shifts in temperatures will accompany the Southwest system. Highs on Saturday will only be in the 80s in Phoenix and Las Vegas, while San Francisco and Los Angeles will barely hit 70.

The TemperatureRadar will show where it will be even colder, with the Pacific Northwest, Mountain West and Great Basin being in the 60s. A few spots of northern Idaho could have their first frosts.

The autumn trend will continue through the rest of the weekend. It will be short-lived. The TemperatureRadar does show 90s returning to the West Coast with triple digit highs in the Desert Southwest by midweek.

Remember to turn on the alerts to get the latest forecast details this weekend.