Clean Energy SF: San Francisco, fog then sun, est. 2026

Vol. 1 - No. 14 - Thursday, September 24, 2026 - Free to readers

Wind ยท Analysis

Where the delta wind meets the grid: Solano County's Montezuma Hills

Northeast of the city, in the one sea-level gap in the Coast Range, the same afternoon pressure that pours fog through the Golden Gate spins one of California's oldest wind corridors. Here is who owns it, and how to check the numbers.

Filed October 30, 2026 By the Clean Energy SF editors Reading time: 6 minutes

I. Why the afternoons do the work

Wind here is not random weather. It is a pressure engine that runs on heat. Through the warm months the Central Valley bakes, the hot air over it rises, and cooler, denser marine air gets pulled inland to take its place. The Coast Range blocks most of that air, but there is one gap at sea level, the stretch of delta and the Carquinez Strait, and the Montezuma Hills stand right in it. The air funnels through and speeds up, hardest in the afternoon and early evening.

The same engine makes San Francisco's summer fog. When inland heat is strongest, the temperature gap is steepest, and the fog and the delta wind pick up together. That also means the resource is seasonal and tied to the time of day, and it is worth being honest about the limits: the hills are quiet on a mild, gray winter day and loud on a hundred-degree inland afternoon in July. Output swings with the weather, which is why no single turbine's nameplate rating tells you what it actually made last year.

II. Who owns the hills

SMUD, the Sacramento Municipal Utility District and a publicly owned utility, is the best known public owner in the Montezuma Hills, with a Solano wind project that has turned here since the 1990s and has been expanded and partly repowered since. It is a plain example of a public agency owning generation outright rather than buying it on contract. Private operators own the larger share, in projects that have carried names like High Winds and Shiloh over the years, developed and held by companies in the EDF Renewables lineage and others.

None of these turbines are wired directly to San Francisco. They deliver into the California Independent System Operator grid (CAISO, the nonprofit that runs the high-voltage network and the wholesale market for most of the state), and providers like CleanPowerSF and Pacific Gas and Electric buy and schedule power on top of that shared system. So the honest answer to whether the city's electrons come from Montezuma Hills is this: some of the region's wind does, and the provider's contracts and the state's disclosure label are where that gets checked.

III. The honest math on capacity and age

Two numbers get quoted loosely about places like this, and both need hedging. The first is capacity, the nameplate rating, which across the Montezuma Hills projects runs on the order of a thousand megawatts combined at last public report, with SMUD's own share a few hundred of that. The second is how much they actually make, which is always lower, because wind is intermittent. A good onshore wind site in California tends to deliver roughly a third of its nameplate averaged over a full year, so treat any big capacity figure as a ceiling, not a promise.

Age matters here too. Some of the original turbines date to the 1980s and 1990s, small by today's standards, and the trend across the corridor has been repowering: taking down many small, older machines and putting up fewer, much taller ones that make more power from the same ground. For the real picture of a specific project, the California Energy Commission's power plant database lists capacity, online date, and owner, and the federal Energy Information Administration publishes generation by plant. Those are the documents to trust over any round number, including the ones in this entry.

IV. Worth watching this month

1. The California Energy Commission's power plant database is the place to catch any new or amended Montezuma Hills listing, which would flag a repowering or expansion, though most months it shows no change.

2. CleanPowerSF's annual California Power Content Label (the state-required disclosure of where a provider's electricity comes from) usually posts in the fall, and it is where to read the wind share in the mix CleanPowerSF actually buys.

3. On the next hot inland afternoon, CAISO's public 'Today's Outlook' page should show statewide wind output climbing as the delta gradient builds, a routine daily rhythm rather than news.

4. SMUD's generation reporting for its Solano wind turbines is a slow-moving figure that tends to confirm the seasonal pattern rather than surprise anyone.

5. Solano County planning notices are where a new wind permit or repowering application would surface, occasional and worth a look when they do.

Frequently asked questions

Does my CleanPowerSF electricity actually come from Montezuma Hills?

Not in a direct, wired sense. The turbines feed the shared CAISO grid, and your provider buys and schedules power on top of it. Some regional wind is in the blend, but no line runs from a Solano turbine to your home.

Is the wind there reliable all year?

No. It is a seasonal, afternoon-heavy resource driven by inland heat. It is strongest from late spring through summer and much quieter on cool winter days.

Who owns the turbines, public or private?

Both. SMUD, a publicly owned utility, owns a share through its Solano wind project, and private companies own the larger portion across projects built over several decades.

How can I check a specific project's size and age?

Open the California Energy Commission's power plant database for capacity, owner, and online date. The federal Energy Information Administration's data covers generation plant by plant.

Why do the fog and the wind seem to arrive together?

They share a cause. The temperature gap between the hot Central Valley and the cool ocean drives marine air through the one sea-level break in the Coast Range, which both pushes fog through the Golden Gate and speeds up wind over the Montezuma Hills.

References