The Unique Summer Weather of the Northern Pacific Coast

Melissa and I are spending July traveling along the coasts of northern California and Oregon, en route from San Francisco to Seattle. When we look at the national news, we see headlines about the extreme heat waves and forest fires that are plaguing parts of the Pacific Northwest.

In case anyone is worried about us, the places we’re visiting are far away from those threats. The Pacific coast in this part of the country is its own unique ecosystem with its own climate. During our time here, the weather has been cool, windy, partly cloudy, and sometimes drizzly (from clouds of fog rather than from rain). Daytime highs this time of year rarely top 65 degrees F, and nighttime lows stay in the mid-50s. The only other place we’ve experienced those temperatures in July was Denmark, where people sat in outdoor cafes in Copenhagen in high summer wearing scarves and warmed by heat lamps.

The difference between the weather on the northern California and Oregon coasts and the weather even a few miles inland is enormous. As we drove north out of San Francisco on Highway 101, the road turned inland. When we stopped for lunch in the cute town of Petaluma, about 25 miles from the coast, the temperature was 98 degrees. That was hot, though with only 24 percent humidity, it felt more tolerable than 98 degrees in humid Washington, DC, or tropical Southeast Asia. Three hours later, when we reached our destination in the coastal town of Fort Bragg, the temperature was in the 50s!

The ocean has so much effect on the local weather that conditions can shift from dense fog to bright sun, and from cool to hot, in the space of a few miles. I always thought of fog as something that rises up from the ground and hangs over streams and low-lying areas. In San Francisco in the summer, it’s the exact opposite. Fog is a great wall of cloud extending in from the sea. Often, you can see it from miles away as you drive toward the city under sunny skies. The fog settles on the city’s many hilltops and creeps downward, swallowing the view, like clouds on a mountain pass.

Wall of fog behind parking lot in Davenport, CA lot
The wall of fog heading for San Francisco Bay is visible in Davenport, CA, more than 60 miles away. (This parking lot is home to refugees from local wildfires in 2020.)

Apparently, in the summer, the layer of moist cloud that hangs over the open ocean (caused by evaporation) gets pulled onshore by the difference in temperature and pressure between the coast and the hot central part of California (the Central Valley). San Francisco, which is surrounded on three sides by the ocean and San Francisco Bay, is especially susceptible to summer fog. But we’ve experienced it farther north, too.

In Ferndale, CA, a little farming town a few miles from the coast, a layer of low cloud hangs over the town like a giant bubble for most of June. (Local people call it the June gloom.) This year, it was still going strong when we stayed there a few days ago. The woman we rented a room from was thoroughly tired of not seeing the sun all day and having to put on a coat to walk to the post office. Though she did say that if she wanted some sunshine, she could just drive 10 miles to the east.

We’ve also encountered coastal fog in Oregon, though usually it burns off in a few hours. Sometimes it hugs the beaches and sometimes only the high headlands. (The photo at the top of this page was taken on Yaquina Head about halfway up the Oregon coast.)

Redwood trees in fog
California’s coastal redwood trees get about half of their moisture from fog

During the summer, northern California and Oregon can go weeks or months at a time with almost no measurable rain. But here on the coast, damp from the frequent fog offers some protection against the wildfires that flourish in the dry conditions inland. (It also helps plants survive the lack of rain.) Forest fires do occur on the coast, but they’re far less common than they are farther inland. Right now, there are no fires on our route north (God willing, it will stay that way).

There’s not much warm weather in the forecast either. The next time we’re here in the summer, we’re going to pack fewer sandals and capris and more long pants.

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