Residents of Northern California’s interior valleys are experiencing continued above-average temperatures, with highs ranging from 95°F to 105°F in many areas, including the Trinity River Valley and Ukiah. The National Weather Service in Eureka has extended the Heat Advisory for interior Humboldt, interior Mendocino, and Lake Counties through Friday, as a strong upper-level ridge keeps temperatures well above seasonal norms.
While the ridge will begin to move eastward tomorrow, bringing a slight reduction in temperatures, highs will remain around 10 degrees above average, with most areas still seeing temperatures in the mid-90s. A cooling trend is expected over the weekend as the ridge breaks down, bringing temperatures closer to seasonal averages.
In addition to the heat, there is a slight chance (less than 10%) of isolated thunderstorms in interior Del Norte County, with even lower chances in northeastern Humboldt and northwestern Trinity counties. These storms are expected to develop as an upper-level trough approaches the coast, bringing some mid-level moisture and a marginal environment for instability.