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  Update: Now Post-Tropical Storm Rachel has made landfall along northern Baja CA north of Ensenada. San Diego is thus spared brunt, but bands of torrential rainfall & severe thunderstorms are occurring from CA's Imperial Valley eastward into AZ, w/serious flash flood threat. #CAwx

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  Just did some number crunching using latest (Oct 1) ECMWF seasonal data, and I must say that I've never seen such high predictive confidence in a very wet California winter. This is a truly extraordinary forecast amid a record-strength El Niño event. [Thread: please read to end.]

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  Global model ensembles are in strong agreement that a prolonged &anomalous nearly West-wide autumn heatwave will develop this week & persist for 10+ days. While some daytime records may be set, this event will be more notable for its persistence & breadth. [Thread]

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  In case you missed it live, this session was recorded and is now available! Remarkably, it now appears that Hurricane Polo has likely become the fastest-strengthening East Pacific hurricane on record (from tropical storm to category 5 strength in ~30 hrs)! https://www.youtube.com/watch?v=9uYYzUFoan4

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  Fielding questions re: this article w/bizarre factual errors. First, there's no "Montecito County" in CA. Second, 2 fires are actually in *Monterey,* & 3rd in *Mendocino*. Third, 60k ac have *not* burned in either fictional Montecito nor real Mendocino.🤨 https://www.latimes.com/california/story/2026-09-12/three-montecito-county-fires-burn-60-000-acres

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  On Thu, Sep 10, at 10am PT I'll offer another major update regarding El Niño 2026, which is still expected to become strongest on record, summarizing latest observations and forecast updates. I'll also revisit potential California-to-global scale impacts. https://youtube.com/live/2v4k0nbUU1s?feature=share

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  At last, a clearer forecast re: California and Marie! Marie is now weakening and will stay well offshore. However, confidence has increased that Marie's remnants will actually have a substantial influence on CA weather for the next 5-6 days! [Thread] #CAwx

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  The ECMWF seasonal ensemble has just updated for September, and it continues to suggest that a soon record-strength El Niño will exert a very strong tilt in the odds toward wet conditions across the U.S. southern tier, including all of California, the Lower Colorado, and SE U.S.

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  On Friday, 9/4 at 10am PT, I'll have a another live Hurricane Maria-focused update on YouTube. I'll share the latest on the forecast evolution, answer your questions re: tropical storms/hurricanes and California weather, and try to dispel some myths. https://youtube.com/live/bbBUWnlPxMk?feature=share

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  In case you missed it live, Tuesday's #ElNiño-focused virtual town hall event hosted by CA Sen Mike McGuire was recorded and is now available. This was a really constructive and worthwhile event; I'd strongly encourage folks to check it out! #CAwx https://www.youtube.com/watch?v=mmmXUkRp6-g

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  I've got 3 live virtual public events on YouTube scheduled over next 8 days (see recent posts for links): 1) Aug 3, 1p PT: WA wildfire disaster & bigger picture 2) Aug 4, 6p: "Super El Niño Town Hall" (CA Sen. Mike McGuire) 3) Aug 10, 1p: El Niño update: The latest forecast

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  In recent weeks, there has been a remarkable surge in large, intense, fast-moving, and unfortunately in many cases destructive/deadly wildfires in multiple Northern Hemisphere regions spanning a wide range of climates & ecologies, but they all share one key commonality. [Thread]

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  Zooming in on Oregon, the enormous scope of ongoing wildfire outbreak is clear. Numerous large smoke plumes from dozens of active fires--which have now burned over 1 million acres in Oregon alone--are casting a broadening pall across the interior Northwest & N. Rockies. #ORwx

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  The extraordinary wildfire outbreak across Oregon, eastern Washington, and southern British Columbia has become even more alarming amid critical fire weather conditions. Over 500,000 acres have already burned in OR & WA alone, and that number could be >1 million acres by Mon.

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  Growing signs of prolonged & potentially intense heatwave across SW by early Aug. A broad Four Corners ridge will strengthen far beyond usual levels on its western flank, possibly due in part to indirect effects from a yet-to-develop East Pacific hurricane. Details TBD. #CAwx

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  Yesterday's "lightning bust" in eastern Oregon & Washington has already resulted in >100,000 acres burned & dozens of new wildfire ignitions. Many are in grass & brush and may be managed soon, but at least 10 are in heavier (forest) fuels and are taking off this PM. #ORwx #WAwx

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  Federal agencies are rapidly moving to curtail the ability of American scientists to collaborate internationally, and this is latest of several dramatic recent developments: "NSF policy set to ban almost all collaborations with Chinese scientists." https://www.science.org/content/article/new-nsf-policy-would-ban-almost-all-collaborations-chinese-scientists

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  A major new wildfire outbreak is now underway across interior Pacific Northwest, with dozens (or more) new wildfires already popping up in eastern Oregon & Washington following tens of thousands of lightning strikes in region experiencing moderate to extreme drought. #ORwx #WAwx

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  A major thunderstorm outbreak is unfolding across the interior Pacific NW. While not "dry thunderstorms" (w/briefly heavy showers), numerous wildfire ignitions are still likely due to strikes outside of rain cores, severe pre-existing drought, & heatwave to follow. #ORwx #WAwx

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  Well, the extreme heatwave across the Northern Rockies/Northern Plains/Upper Midwest is living up to expectations with some locations (as of only 2pm local time) reaching or breaking all-time (any month) temperature records today in Wyoming and eastern Montana. #MTwx #WYwx

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  Another month & another upward shift in predicted #ElNiño peak intensity (between Oct & Dec) in the multi-model ensemble median. The single most likely outcome is now a very strong ("Super") El Niño event; a record-breaking event is possible, but not guaranteed. Full steam ahead.

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  On Thu, Jul 9 at 11am PT, I'll have a livestream to discuss building "heat dome" that will eventually expand to encompass most of western & central US by mid Jul. I'll discuss impacts, including record heat, wildfire risk, & monsoon moisture/thunderstorms. https://youtube.com/live/Uys8re8I0BI?feature=share

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  I just submitted my formal comment on the disastrous proposal to transform essentially all U.S. federal grantmaking--affecting every sector of American science, technology, education, & health--into an overtly partisan political process. Full text here: https://weatherwest.com/wp-content/uploads/2026/07/Daniel-Swain-comments-on-OMB-proposed-rule-changes-July-2026.pdf

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  I wanted to share my thoughts on the proposed OMB rule change that would radically transform federal grant-making into an overtly partisan political process. It's highly alarming, and would be devastating for American science (among many other things). https://youtu.be/ZyBibk4a6Vs?si=Bg1KCBtDR1wOTKir

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  There are growing indications that large, intense, & perhaps record-breaking mid-atmospheric high pressure system (aka a "heat dome") will develop somewhere between Rockies & Central Plains by mid-Jul. This could bring a widespread & severe heatwave across much of the U.S.

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  Unfortunately the interior West wildfire outbreak has continued to intensify under "extremely critical" fire weather conditions today and record-dry vegetation in some areas. Existing fires have re-intensified, and there are 2 new fires of particular concern in Colorado. [Thread]

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  NOAA SPC has once again upgraded today's fire weather risk in western Colorado & Four Corners region to "extremely critical"--marking rare third consecutive day. Multiple existing fires will likely make further large runs today, & new ignitions willl take off quickly. #COwx #AZwx

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  NOAA once again highlighting a rare, highest-end "extremely critical risk" region today around Four Corners/CO Western Slope for exceptionally adverse fire weather conditions amid severe drought. Numerous lightning holdovers are popping up during unusual summer wind event.

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  On Thursday, Apr 16 at noon PT, I'll have a "lunch hour" livestream to discuss the already prolonged & severe marine heatwave affecting Pacific ocean near California. Also: are upcoming April showers connected to a West Pacific supertyphoon? https://youtube.com/live/SIRF3D4-ccs?feature=share

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  I'll have another "lunch hour" live virtual office hour at 12 noon PT on Tue, Apr 21, to discuss continuation of an unusually active spring weather pattern in California, broader context of strange 25-26 Water Year, and links to now record-warm NE Pacific. https://youtube.com/live/nic7KSZMyE0?feature=share