{"id":143293,"date":"2026-01-21T16:40:18","date_gmt":"2026-01-21T16:40:18","guid":{"rendered":"https:\/\/www.newsbeep.com\/us-ca\/143293\/"},"modified":"2026-01-21T16:40:18","modified_gmt":"2026-01-21T16:40:18","slug":"why-is-fog-so-heavy-in-the-sacramento-valley-and-when-will-it-end","status":"publish","type":"post","link":"https:\/\/www.newsbeep.com\/us-ca\/143293\/","title":{"rendered":"Why is fog so heavy in the Sacramento Valley and when will it end?"},"content":{"rendered":"

(FOX40.COM) \u2014 For the last few weeks, the Sacramento Valley has experienced extremely dense fog, leaving residents wanting to know what\u2019s causing it and when it will end.
\u2022 Video Above: Dense fog creates dangerous conditions in the Sacramento Valley<\/p>\n

According to FOX40 chief meteorologist Adam Epstein<\/a>, the heavy fog, particularly at night, is caused by air pollution \u2013 and it might be around for a while.<\/p>\n

\"<em>Dense<\/a><\/p>\n

Dense fog fills the atmosphere in the Sacramento Valley on Jan. 19, 2026.\/FOX40 <\/p>\n

\u201cPollutants have been combining with fog, sinking into the Valley each night, then getting trapped by a dome of high pressure,\u201d Epstein said. \u201cThe air quality has been less than ideal because of it.\u201d<\/p>\n

Foggy conditions are prominent in the Central Valley. However, it\u2019s particularly thick around the Sacramento area.<\/p>\n

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\u201cSo what\u2019s happening is, every night, the cold air is filling the valley and we\u2019re getting that fog to form \u2014 and also pollutants are getting trapped at the surface under what\u2019s called an inversion,\u201d Epstein said.<\/p>\n

The inversion keeps the colder air below the warmer air. Under those conditions, high pressure pushes down on everything, and because there\u2019s no wind or movement in the atmosphere, it remains still, except for the accumulation of more pollutants in the air.<\/p>\n

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\u201cThe pollutants accumulate each day, and each day, you have bad air quality,\u201d Epstein said.<\/p>\n

\u2018Mixing\u2019 could get rid of the fog. Mixing is a vertical stream of wind that would essentially clean out the air and improve air quality. A rainstorm could also clear the fog.<\/p>\n

Currently, the air quality in the Sacramento Valley is poor.<\/p>\n

\u201cAnytime the AQI (air quality index) gets over 150, I think twice about spending too much time outside,\u201d Epstein said. \u201cYou might not feel like yourself, but it affects everyone differently.\u201d<\/p>\n

The fog is expected to leave once the region gets another storm, which isn\u2019t forecast to happen until the end of January or early February.<\/p>\n

Copyright 2026 Nexstar Media, Inc. All rights reserved. This material may not be published, broadcast, rewritten, or redistributed.<\/p>\n

For the latest news, weather, sports, and streaming video, head to FOX40 News. <\/a><\/p>\n","protected":false},"excerpt":{"rendered":"(FOX40.COM) \u2014 For the last few weeks, the Sacramento Valley has experienced extremely dense fog, leaving residents wanting…\n","protected":false},"author":2,"featured_media":143294,"comment_status":"","ping_status":"","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[32],"tags":[71827,1842,39366,121,123,122,23136],"class_list":["post-143293","post","type-post","status-publish","format-standard","has-post-thumbnail","category-sacramento","tag-adam-epstein","tag-air-pollution","tag-dense-fog","tag-sacramento","tag-sacramento-headlines","tag-sacramento-news","tag-sacramento-valley"],"_links":{"self":[{"href":"https:\/\/www.newsbeep.com\/us-ca\/wp-json\/wp\/v2\/posts\/143293","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.newsbeep.com\/us-ca\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.newsbeep.com\/us-ca\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.newsbeep.com\/us-ca\/wp-json\/wp\/v2\/users\/2"}],"replies":[{"embeddable":true,"href":"https:\/\/www.newsbeep.com\/us-ca\/wp-json\/wp\/v2\/comments?post=143293"}],"version-history":[{"count":0,"href":"https:\/\/www.newsbeep.com\/us-ca\/wp-json\/wp\/v2\/posts\/143293\/revisions"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/www.newsbeep.com\/us-ca\/wp-json\/wp\/v2\/media\/143294"}],"wp:attachment":[{"href":"https:\/\/www.newsbeep.com\/us-ca\/wp-json\/wp\/v2\/media?parent=143293"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.newsbeep.com\/us-ca\/wp-json\/wp\/v2\/categories?post=143293"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.newsbeep.com\/us-ca\/wp-json\/wp\/v2\/tags?post=143293"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}