Take a trek to the rainiest spot in SLO County — 3,245-foot Rocky Butte

On the rugged North Coast, there’s a place high atop a remote mountain that’s known as the rainiest spot in San Luis Obispo County.

It takes an hour and a half to get there from San Luis Obispo, it’s not open to the public and when you reach the top, you’re more than twice as high as Bishop Peak.

Rocky Butte, a peak east of San Simeon that rises 3,245 feet above sea level, almost seems like a magical oasis, an island of green in a sea of rolling golden hills.

It’s sandwiched between Hearst Castle and Lake Nacimiento, and on a clear day, you can see for miles.

Most people probably have never heard of the spot. That is, unless you’re something of a weather buff, like PG&E meteorologist John Lindsey. In that case, Rocky Butte is almost legendary.

When we asked San Luis Obispo County’s preeminent weather expert if he could guide us to the rainiest place in the county, not only did he agree, he was downright giddy about the idea.

Built for rain

It may seem as though Rocky Butte gets all of its rainfall from magical properties, but it actually has its unique geography to thank.

Lindsey said an effect known as an “orographic lift” helps enhance the amount of precipitation that falls on the mountain.

Basically, wind blows off the ocean and carries moist air up over Rocky Butte’s ridges. The high elevation causes the air to cool and the moisture to condense, creating rain.

“It’s literally like wringing out a sponge,” he said.

As a result, the peak will easily receive more than double the rain San Luis Obispo does, and three, four or five times what falls in Paso Robles.

Last year — one of the wettest in decades — the county rain gauge atop Rocky Butte had measured 87.11 inches of precipitation by this time, compared to 36.19 inches at Cal Poly and 14.74 at the Paso Robles Airport, Lindsey said.

This year, the peak has received 13.47 inches of rain, compared to 6.28 inches at Cal Poly and 5.81 inches at the Paso Robles Airport.

Adventure trip

Getting to Rocky Butte from San Luis Obispo is a trek to say the least, and not just anyone can go there. We needed special permission, a county escort and Lindsey in the driver’s seat of a four-wheel-drive SUV.

After turning off Highway 1 onto San Simeon Road, we headed off on a private road that winds to the peak.

Only a few private landowners and the county have access to a gate that opens onto a steep, bumpy dirt path through a densely forested area.

Lindsey, who had only visited Rocky Butte one other time, was especially excited to see the wildlife and experience the forest-like setting.

Here, deer and wild turkeys — he called them “turkeys in the mist” — roam the sparsely populated woodlands. Technicolor-green moss grows on the trees, and a waterfall flows over rocks on the side of one stretch of road.

On a rainy day, the damp fog fills the air all the way up the mountain, and it gets colder and colder the higher you climb.

At one point, Lindsey, ever on the lookout for Twitter material, stopped to take a group photo next to a sign pointing the way toward the Rocky Butte Truck Trail.

Off the beaten path

Rocky Butte is the most remote of the county’s rain gauges, according to Ray Dienzo, the technical unit supervisor in the Water Resources division of the county Public Works Department who also joined us for the trek.

In the competition for most-difficult-to-reach rain monitors, only Davis Peak east of Montaña de Oro comes somewhat close, but it’s already much closer to San Luis Obispo.

When you near Rocky Butte’s summit, blackened trees dot the landscape and pink streaks of fire retardant color the ground — persistent remnants of the Chimney Fire that threatened Hearst Castle in 2016.

County and state radio facilities and a solar-powered rain gauge line the peak, which Dienzo jokingly called “the ring of power.” Hearst Castle and Lake Nacimiento can even be seen on a clear day.

Even through the fog, the Oak Shores community that lines one side of the lake is visible — the curves of the blue lake cutting through the white mist.

The county’s radio tower transmits data from the tipping bucket rain gauge — which is hidden inside a tube-like structure — down the mountain to the county’s offices.

A gauge of Nacimiento

The Rocky Butte rain gauge is particularly important to the county because it can be used to monitor precipitation being deposited into Lake Nacimiento, Dienzo said.

“This captures a lot of what’s going into this watershed,” he said.

On a stormy afternoon, the peak is not the most comfortable spot in SLO County, and a cold wind whips up and over the peak’s ridges, visibly demonstrating the orographic lift effect as it pushes misty air around the summit.

Lindsey took videos of the swirling gusts, excited to witness the “physics of weather” in action.

It won’t be long before more rain is on the way.

This story was originally published March 9, 2018 at 2:17 PM with the headline "Take a trek to the rainiest spot in SLO County — 3,245-foot Rocky Butte."