The dense fog advisory goes into effect at 2 a.m. Friday, Friday, Feb. 27, and impacts communities including Fresno, Merced, Bakersfield, Clovis, Hanford, Madera, Porterville Reedley and Visalia.<\/p>\n
Here\u2019s what to know:<\/p>\n
How long will fog last in Fresno?<\/p>\n
The dense fog advisory will remain in effect through 10 a.m. Friday, the weather service said.<\/p>\n
\u201cVisibility one quarter mile or less\u201d is possible on local roads, making \u201cdriving conditions hazardous,\u201d the weather service said in its advisory.<\/p>\n
\u201cSignificant travel delays<\/a>\u201d are expected Friday and Saturday, the weather service said in a Tuesday, Feb. 24, post on X.<\/p>\n The fog comes from high pressure building<\/a> over central California, the weather service said in an X post on Wednesday, Feb. 25.<\/p>\n With high pressure building in over central California over the next few days, stable conditions will bring back chances for dense fog in the San Joaquin Valley. This image shows the percent chance for quarter mile visibilities for Thursday morning, February 26th. #CAwx<\/a> pic.twitter.com\/aRibJ77Ag3<\/a><\/p>\n \u2014 NWS Hanford (@NWSHanford) February 25, 2026<\/a> Why is it so foggy in the Central Valley?<\/p>\n These low-lying clouds typically form in the valley during the colder months when winds are light and the soil is moist.<\/p>\n Tule fog becomes especially dense when moist marine air<\/a>, calm winds and clear skies come together.<\/p>\n \u201cThe Central Valley is fertile ground for the formation of tule fog, a persistent radiation fog, in late autumn and winter,\u201d NASA said.<\/p>\n \u201cThe perfect recipe for radiation fog … is for there to be low-level moisture, clear skies and light winds,\u201d said former National Weather Service forecaster Jan Null, a professor of meteorology at San Jose State University.<\/p>\n Null said the area\u2019s early fall weather patterns caused a perfect storm for a particularly heavy fog year.<\/p>\n Driving in foggy conditions<\/p>\n Take extra caution<\/a> when on the road or avoid driving if possible. If you must drive in foggy conditions, keep the following safety tips in mind, the National Weather Service said:<\/p>\n Slow down and allow extra time to reach your destination.Make your vehicle visible to others both ahead of you and behind you by using your low-beam headlights since this means your taillights will also be on. Use fog lights if you have them.Never use your high-beam lights. Using high-beam lights causes glare, making it more difficult for you to see what\u2019s ahead of you on the road.\u00a0Leave plenty of distance between you and the vehicle in front of you to account for sudden stops or changes in the traffic pattern.To ensure you are staying in the proper lane, follow the lines on the road with your eyes.In extremely dense fog where visibility is near zero, the best course of action is to first turn on your hazard lights, then simply pull into a safe location such as a parking lot of a local business, and stop.If there is no parking lot or driveway to pull into, pull your vehicle off to the side of the road as far as possible. Once you come to a stop, turn off all lights except your hazard flashing lights, set the emergency brake, and take your foot off of the brake pedal to be sure the tail lights are not illuminated so that other drivers don\u2019t mistakenly run into you.<\/p>\n Loading\u2026<\/p>\n Related Stories from Fresno Bee<\/p>\n
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