SLO County Rainiest Spot in Southern California: How Much Fell?

This post translates a two-day rainfall briefing from San Luis Obispo County into a Marin-focused look at where the rain piled up and how the terrain shaped the totals. It also considers what our North Bay towns might want to watch for as the weekend weather unfolds.

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Two-Day Rain Totals Across San Luis Obispo County

The rainfall map from the last 48 hours shows a pretty wide range—from a light drizzle to a solid downpour—depending on coastal and mountain terrain. For Marin readers, it’s a reminder: our hills and coastal slopes can see similar patterns, even if our totals aren’t quite as dramatic. Rocky Butte, northeast of Cambria, grabbed the top spot with a striking 3.51 inches, making it the wettest spot in Southern California for this storm.

Rocky Butte (northeast of Cambria): 3.51 inches
Cambria: 1.24 inches
Arroyo Grande: 1.12 inches
Morro Bay: 0.33 inch
Los Osos: 0.83 inch
San Luis Obispo regional airport: 0.86–1.19 inches
Downtown SLO (Broad Street and Industrial Way): 0.89 inch

Inland and northern parts of the county showed some real variability. North County totals ranged from a modest 0.37 inch in Shandon to a solid 1.82 inches west of Santa Margarita. Santa Margarita East recorded 1.02 inches.

Shandon: 0.37 inch
West of Santa Margarita: 1.82 inches
Santa Margarita East: 1.02 inches
Nipomo: 0.55 inch
Oceano: 0.96 inch

The southern reach of the county stayed drier, with Nipomo at 0.55 inch and Oceano near 0.96 inch. The inland valleys and mountains told a different story. Las Tablas logged 1.98 inches, the Nacimiento River gauge hit 1.74 inches, and Upper Lopez got 1.04 inches.

Smaller alpine sites posted lighter totals. Branch Mountain saw 0.84 inch, Bald Mountain picked up 0.71 inch, and La Panza ended up with just 0.40 inch.

Regional Patterns and Local Variability

What really jumps out here is how quickly amounts change with elevation and exposure. Coastal slopes near Cambria and central coast towns saw decent rain, while patchier totals popped up in nearby urban pockets and along the inland foothills.

For Marin folks, the takeaway’s pretty clear: even when a storm’s core isn’t right overhead, our terrain can funnel moisture into tight bands that drench hillsides, burn-scar areas, and watershed outlets just a short drive away. Makes you wonder what the next round might bring, doesn’t it?

Forecast and Marin Outlook

The National Weather Service says there’s a 70% chance of rain Sunday afternoon. Skies should clear up at night, and Monday morning brings sun with just a 20% chance of afternoon showers.

For Marin, that means a dry start to the workweek. Still, expect slick roads and some runoff, especially east of Mill Valley, around Fairfax, and along the San Geronimo Valley corridor.

Keep an eye on local advisories. Coastal systems can flip the script fast, even when the big-picture forecast looks calm.

Watch creek levels in Mill Valley and San Rafael as rains let up.
Roads could stay slick Monday morning in Santa Venetia and Tamalpais until the ground dries out.
Check drainage in Sausalito and Tiburon near the waterfront after heavy showers—ponding can sneak up on you.

Marin County keeps cycling through marine layers and quick winter showers. Terrain really shapes how things play out here.

From Santa Barbara to the Santa Lucia Range and up to the Marin hills, sudden downpours can catch drivers and hikers off guard. Maybe check National Weather Service alerts, or tune into local news in San Rafael, Novato, or Corte Madera if you want to stay ahead of the weather.

If you’re heading toward Point Reyes Station, Larkspur, or Ross, plan for wet roads just in case. Around here, a little patience—and being ready—goes a long way when these coastal storms roll through.

Here is the source article for this story: SLO County spot was rainiest in Southern California during storm. How much fell?

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Joe Harris is the founder of MarinCountyVisitor.com, a comprehensive online resource inspired by his passion for Marin County's natural beauty, diverse communities, and rich cultural offerings. Combining his love for exploration with his intimate local knowledge, Joe curates an authentic guide to the area featuring guides on Marin County Cities, Things to Do, and Places to Stay. Follow Joe on Facebook, Twitter, and Instagram.