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By Alan Smith, Meteorologist Posted 8 months ago October 2, 2023

September 2023 Review & October Outlook for the Western U.S.

Fall is well underway across the West as the leaves are hitting peak color in the mountains, while snow is also becoming more common across the higher elevations. October is expected to be a fairly active month in terms of rain and snow chances with Pacific storm systems expected to make landfall on a somewhat regular basis. 

September 2023 Review:

Overall, September was a very pleasant month for most areas as summer began to transition into fall. At a larger scale, there were not any extremes in terms of temperatures, precipitation, or wildfires relative to normal.

Rainfall was above normal for many areas of the West during September, including the Pacific Northwest, Northern California, Great Basin, and Northern Rockies. These regions were impacted by significant storm systems over Labor Day weekend and around September 20th-24th.

Conditions were drier than average across the Southwest as well as Western Colorado, though parts of the Colorado Front Range did see above-average rainfall.

Many high-elevation areas, including the summits of some ski resorts, saw their first snow events of the season during September as well. This was especially true later in the month when cooler air arrived. This was nothing out of the ordinary, but it's always exciting to see the first dustings of snow on the peaks as the seasons change.

Temperatures were warmer than average across the Rockies and Intermountain West in September, but we also did not see any major late-season heatwaves as temperatures cooled off nicely from July-August levels. The exception was Southern New Mexico where the late-season heat was rather excessive.

Temperatures were closer to average across the West Coast states and were even a bit cooler than average along the California Coast.

October 2023 Outlook:

The first few days of October are proving to be wet and cool across portions of the Northwest, Great Basin, and Northern Rockies, and this includes significant snow for the upper portions of ski areas from Utah into the Northern Rockies. 

As the month progresses, most areas will see alternating periods of wet and dry conditions with snow falling across the higher terrain. 

NOAA is projecting above-average precipitation for most of the West, except for the Pacific Northwest where near to below-average precipitation is projected. However, the medium-range outlook for the PNW is actually looking quite wet heading into mid-October, so we'll see whether or not NOAA's below-average projection holds true.

Despite the active pattern, temperatures are expected to be warmer than average throughout the West as the pattern will not be conducive to early-season cold air shots arriving from the Canadian Interior.

Rather we will probably see cool but moderated Pacific air arrive with storm systems, with warmer temperatures in between storms – not necessarily a bad thing if you're hoping to enjoy a few more weeks of summer/snow-free activities before winter sets in.

Keep in mind that "average" temperatures decrease rapidly over the course of the month in October. So just because the signal is for "above average" for the month as a whole, that doesn't mean we won't be seeing chilly temperatures with shots of mountain snow. 

Fire and Smoke Outlook:

Fire season is winding down for most mountainous regions of the West. Aside from parts of Oregon, this has been a mild fire season for most of the Western U.S. while conditions were much more severe north of the border in Canada.

Heading into October, no areas of "above normal" significant wildland fire potential are projected across the Contiguous Western U.S. And the Santa Ana wind region of Southern California is expected to see below-normal fire potential, which is great news as fall is the peak season for Santa Ana winds. 

Keep in mind that occasional high fire danger days will be possible in drier regions prone to high winds during the fall. 

El Niño and the Winter Ahead:

El Niño conditions have developed in the Pacific, and confidence is increasing that we will experience a strong El Niño this winter, meaning that ocean temperatures in the Eastern Equatorial Pacific are well above normal.

Seasonal forecasts are always a challenge because there are many factors that cannot be anticipated ahead of time, but we do have some clues on which areas may be more favored for above or below-average snowfall based on past El Niño winters. 

Our forecasters have been writing articles over the past several weeks explaining the science behind El Niño, other factors aside from El Niño that could influence the Western U.S. winter, and Winter Forecast Previews for regions across the West.

Check out these articles we've posted so far, and stay tuned for more as winter approaches...

U.S. Winter Forecast Preview

El Niño Is Strengthening, Potential 2023-2024 Impacts

How Atlantic Ocean Temps Could Impact El Niño & 2023-2024 Winter Forecast

El Niño's Effect on Atmospheric Rivers

Colorado Winter Forecast Preview

Jackson Hole Winter Forecast Preview

British Columbia Winter Forecast Preview

Palisades Tahoe Winter Forecast Preview

Oregon Winter Forecast Preview

Washington Winter Forecast Preview

Montana Winter Forecast Preview

Alan Smith, Meteorologist

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About The Author

Alan Smith

Meteorologist

Alan Smith received a B.S. in Meteorology from Metropolitan State University of Denver and has been working in the private sector since 2013. When he’s not watching the weather from the office, Alan loves to spend time outdoors skiing, hiking, and mountain biking, and of course keeping an eye on the sky for weather changes while recreating.

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