FXUS66 KEKA 202148 AFDEKA AREA FORECAST DISCUSSION National Weather Service Eureka CA 248 PM PDT Sun Sep 20 2026 .KEY MESSAGES... * Warmer and drier interior temperatures begin to slowly ease on Monday. * A shallow but strong marine layer along shore will weaken with some clearing by possible by Tuesday. * Cold front late in the week with a 20% chance of light wetting rain along the North Coast. && .SYNOPSIS...High pressure has peaked today with warm conditions across the interior and thin but persistent marine clouds near shore. Low pressure passing south will cool conditions in the coming days with clearer skies possible along shore by Tuesday. && .DISCUSSION...High pressure peaked across the area today. Many interior valleys reach into the upper 80s, though some passing upper level clouds took the edge off heat, especially for the southern half of the area. A persistent but shallow marine layer has continued to keep the coast blanketed in clouds. Low pressure moving into the Central California Coast will help to ease high pressure over the next couple of days. By Tuesday, high temperatures in the interior will most likely drop back below 80 degrees. Marine influence will pull more inland, giving some chance for fog for near coastal valleys. Weak east flow on the back end of the low pressure will bring better chance for clearing along the coast, especially on Tuesday and Wednesday. Ensemble models have started to show better clarity for the forecast by late weak. Most show high pressure weakly and briefly reforming around Thursday. A cold front is expected to cross the area around Friday, helping to drop interior highs into the low and mid 70s for next weekend. The front will also disrupt and lift any marine layer that manages to reform on Thursday. Most models still show the front mostly dry, but now about 20% show very light wetting rain focused along the North Coast. Weak high pressure is most likely to quickly rebuild behind the front. Despite the cooler air, there is little potential (20% or less even for the coldest valleys) for frost behind the front. /JHW && .AVIATION...High pressure has again enabled a persistent deck of marine stratus all along shore through the day. Ceilings have barely lifted to MVFR with just a few breaks expected through the afternoon. Ceilings will most likely gradually fall back to IFR conditions overnight though true LIFR conditions remain unlikely. High pressure will weaken in the coming days. increasing ht potential for clearer skies. /JHW & .MARINE...Moderate to isolated strong north winds have now built throughout the outer waters, though condition remain calmer closer to shore, especially north of Cape Mendocino. Short period seas have built in response to the winds with waves over 8 feet in the outer waters and some steep seas up to 6 feet migrating into the inner waters. Similar winds will persist for the next several days and even strengthen in the southern outer waters with some near gale conditions by Tuesday morning. Winds will gradually weaken form north to south mid to late week as a cold front approaches. Short period wind waves will continue to dominate the environment alongside a very minor southwest swell. /JHW && .EKA WATCHES/WARNINGS/ADVISORIES... CA... None. NORTHWEST CALIFORNIA COASTAL WATERS... Small Craft Advisory until 9 PM PDT Tuesday for PZZ455-470- 475. && $$ NOTE: The full forecast discussion is now regularly issued between 10 am/pm and 1 pm/am. Additional updates will be issued as needed. Visit us at https://www.weather.gov/eureka Follow us on Facebook and Twitter at: https://www.facebook.com/NWSEureka https://www.twitter.com/NWSEureka For forecast zone information see the forecast zone map online: https://www.weather.gov/images/eka/zonemap.png