I think probably what you are describing are hazelnuts, also known as filberts. There are a couple of varieties that grow wild in this region.

One species is native here, it blooms later. The ones in bloom are orchard kinds.

Hmmm...the ones in our greenbelt woodland in north Edmonds are blooming now.
Always thought they were native Corlyus cornuta.

CULTIVATED FILBERT ... which is European in origin, was once a major orchard crop in our area, especially on the Eastside and Vashon. Both the large, leftover specimens from cultivation and completely wild youngsters are common. They differ from WESTERN BEAKED HAZEL in several ways: Besides being larger and more robust, they bloom in January, ripen larger nuts later in fall, and have larger, thicker leaves. Both FILBERTS and HAZELS grow in exactly the same places, sometimes side by side

--A.L. Jacobson, Wild Plants of Greater Seattle - Second Edition (2008)

Native Corylus cornuta, western hazelnut, is blooming early this year. As in right now. And no, they're not feral filberts, but thanks bboy for the tips.

Actually it's quite easy for many deciduous plants to id in winter without the leaves. Buds and twigs are often quite distinctive by themselves, and I find myself looking for the bud and twig characteristics even in spring and fall when leaves are present.

Alders are starting to put out their catkins already too.

These current weather conditions are typical of March, not January, so it's not at all surprising to see plants respond as if it were March.

Like March? Flowering currants are just swelling now, alders are not yet fully out. If I've gone by any California hazels in bloom, I don't remember it. Filberts have been out for some time. It's almost February, soon it will be the normal time for California hazel to bloom.

Might have seen some California hazels in bloom yesterday, from the freeway.