California—California is about to trade its unusual September heat for a much cooler pattern as Pacific breezes push across the state and much of the western United States.
The dramatic shift follows several days of temperatures running as much as 20 degrees above historical averages for mid-September. The heat reached its peak along much of the California coast on Wednesday before spreading into interior areas on Thursday.
San Francisco, downtown Los Angeles and Long Beach all experienced their highest temperatures of the year so far on Wednesday.
San Francisco climbed to 94°F, while downtown Los Angeles reached 105°F. Long Beach became even hotter, hitting 107°F. All three locations set daily record highs.
The heat also pushed inland Thursday, when Fresno challenged its daily record of 108°F, a mark that has stood since 1888. Las Vegas likewise challenged its daily record of 108°F, set in 1945.
But the intense heat is now expected to lose its grip as winds increasingly come from the Pacific rather than the deserts.
Pacific Breezes Will Bring Temperatures Back Down
As the weather pattern changes, temperatures across California should move closer to their historical averages.
San Francisco is expected to return to highs generally in the mid-70s, while temperatures along Southern California beaches should settle into the mid-80s.
Downtown Los Angeles will remain warmer, with temperatures still projected to reach around 90°F, keeping the city several degrees above its normal level.
By this weekend, much of the Southwest should see temperatures near average.
However, cooler temperatures will not necessarily mean completely comfortable conditions everywhere. Humidity could remain elevated, particularly across Southern California, even as the extreme heat fades.
The combination of changing winds and cooler Pacific air will mark a noticeable break from the unusual heat that dominated the region earlier in the week.
Northwest Braces for an Early Taste of Fall
While California cools down, the Northwest is preparing for an even sharper weather change.
A faster-moving storm will push colder air from the Washington and Oregon coasts toward the northern Rockies, bringing temperatures well below the levels seen during the middle of the week.
Along the Northwest coast, temperatures could fall 5 to 10 degrees below historical averages this weekend.
The colder air may also bring scattered showers and thunderstorms. Some of those storms could produce small hail, adding another element to the rapidly changing weather pattern.
For residents who have been experiencing late-summer warmth, the conditions could begin to feel much more like fall.
Mountain Snow Could Arrive This Weekend
The biggest sign of the cooldown may come at higher elevations.
As a pocket of chilly air moves across the Northwest, some ridges and peaks in the Cascades and Olympic Mountains could receive accumulating snow this weekend.
The northern Rockies will also see a major temperature drop. Highs in the 40s, 50s and 60s are expected to replace the midweek temperatures that had reached the 80s and 90s.
Record Heat Grips Central U.S.— Millions Could See Record-Breaking Temperatures Through Friday
The incoming storm will spread scattered rain showers and thunderstorms across parts of the interior Northwest and northern Rockies.
As the atmosphere becomes colder, precipitation will increasingly change from rain to wet snow over the highest terrain. Some intermediate elevations in Idaho and western Montana could even see a mixture of rain and wet snow.
Western Weather Pattern Takes a Dramatic Turn
The contrast between the week’s beginning and the weekend highlights just how quickly weather conditions can change across the West.
California is moving away from record-breaking September heat, while areas farther north prepare for chilly temperatures, rain and the possibility of the season’s first accumulating mountain snow.
The cooldown will not erase every trace of summer warmth, particularly in Southern California, where temperatures are expected to remain somewhat above average in places. Still, the broader pattern is shifting toward cooler conditions, especially across the Northwest and northern Rockies.
For mountain communities and travelers, the arrival of wet snow at higher elevations could provide an early reminder that fall is quickly approaching across the western United States.
Are you ready for the sudden shift from record heat to fall-like weather? Tell us what the weather is like where you live in the comments below.