Muir Beach Weather

June, July, and August are the clear winners at Muir Beach. The data backs this up: June 2024 saw highs averaging 76°F with a comfort score of 88 out of 100, zero rainfall, and over 12 hours of sunshine per day. July and August matched that performance closely, with highs in the mid-70s and essentially no rain. September is also excellent, often reaching into the upper 70s with comfort scores around 87. The pattern here is that Muir Beach performs like a classic Northern California coastal gem in summer: warm enough to be comfortable, rarely hot enough to be oppressive, and the fog that defines San Francisco's summer is lighter here than it is closer to the Golden Gate. Morning fog averages just 1.7 to 2.3 hours per day during peak summer months, which means by 10 or 11 a.m., you're usually looking at open sky. Fall is worth a mention too. September 2025 logged a comfort score of 83 with highs around 68°F, and October still delivers occasional warm, clear days. The worst months are November through January, when rainfall climbs above 8 inches in the worst cases and comfort scores drop into the 60s. For the best Muir Beach experience, plan your visit between late June and mid-October.

Muir Beach stays mild by most standards, but winter here is genuinely gray and wet rather than just cool. Average highs from November through February hover in the upper 50s, typically between 56°F and 59°F, with lows dropping into the mid-40s. That is not freezing, but combined with coastal wind and frequent overcast skies, it feels colder than the numbers suggest. November 2025 was one of the harder months on record in this dataset: highs averaging just 56.8°F, 8.36 inches of rain, and a comfort score of 66 out of 100. December 2025 was similar, with only 6.2 hours of sunshine per day. The fog pattern in winter is different from summer. Instead of morning marine layer that burns off by late morning, winter brings low cloud decks that can persist all day, and the rain comes in storm systems rather than drizzle. There are beautiful windows between winter storms when Muir Beach is genuinely stunning, green and dramatic. But if you are looking for reliable warmth and sunshine, winter is not the season. For more context on how Bay Area rainfall patterns shape coastal visits, see the rainiest month in the Bay Area.

Muir Beach sits at just 10 feet of elevation right at the water's edge, which means it is fully exposed to the Pacific's moderating influence year-round. The range is remarkably narrow for a California coastal location: average highs peak around 76°F in the warmest months (June and September tend to be the hottest based on recent data) and drop to the upper 50s in the coldest winter months. Lows bottom out around 44°F to 48°F in winter and stay in the mid-50s through summer. What that means in practice is that you will almost never experience a scorching afternoon at Muir Beach. The ocean keeps things honest. Even in the best summer months, highs averaging 74°F to 76°F are the norm, not 85°F or 90°F. This is actually the appeal: the beach is comfortable for long stretches of the afternoon without the heat stress you might find at inland destinations. The tradeoff is that the water temperature does not cooperate with the air temperature. Pacific Ocean water along this stretch of Marin coast runs cold year-round. For the broader picture of how Bay Area temperatures vary across different seasons and locations, the Bay Area four seasons guide is worth reading.

Fog is a real factor at Muir Beach, but not the relentless wall of marine layer you might expect given its location south of Stinson and just outside the Golden Gate. The data shows morning fog averaging 2.3 hours per day in August, 2.1 hours in June, and about 2.7 hours per day in both June and July 2025. Those are meaningful but manageable windows. Most days, the fog rolls in overnight or in the early morning and clears by 10 a.m. to noon, leaving the afternoon open and sunny. The exceptions worth knowing: June 2025 was notably foggier than the prior year, logging 4.5 hours of morning fog per day and a comfort score of 78, compared to June 2024's 2.1 hours and score of 88. Year-to-year variation at coastal spots like this is real, and some June mornings genuinely stay gray all day. October starts to see more fog again (3.7 hours per day in October 2025), but that fog is different in character from summer marine layer, often associated with onshore moisture rather than the classic thermal-driven California coastal fog pattern. For a deep explanation of how and why coastal fog forms along this stretch of Northern California, the guide to how fog forms along the Northern California coast covers the mechanics well.

Yes, coastal wind is part of the Muir Beach experience, and it is worth planning for. The cove shape of the beach provides some shelter compared to fully exposed headlands nearby, but afternoon onshore winds are a consistent feature from spring through early fall. The wind typically picks up after noon as the Central Valley heats up and draws marine air inland through coastal gaps. By 2 or 3 p.m. on a summer day, winds of 10 to 20 mph are common. This is exactly why the comfort scores remain in the 80s rather than climbing higher despite warm temperatures: even at 74°F, a steady ocean breeze can make a t-shirt feel inadequate. Morning visits avoid the worst of it. If you arrive at 9 or 10 a.m., you often get glassy calm conditions for a couple of hours before the wind builds. The wind does not typically reach storm-level intensity on summer afternoons, but it is persistent and cooler than the air temperature suggests. For more on the regional wind patterns that affect all Bay Area coastal destinations, the Bay Area wind guide explains the mechanics clearly. The nearby Rodeo Beach is similarly exposed and offers a useful comparison point.

The layering approach that applies across the Bay Area coast applies at Muir Beach in particular. This is a place where arriving in shorts and a t-shirt is a gamble, even in summer. Here is how to think about it: pack for a morning in the low 60s with potential fog, an afternoon that might reach the low 70s with full sun, and persistent wind off the water that can drop the feels-like temperature 10 to 15 degrees below the air temperature. A light windproof jacket or softshell is the single most useful item you can bring. It blocks the afternoon breeze without making you sweat if the sun breaks through. Underneath, a long-sleeve layer gives flexibility. For footwear, the beach itself is sandy and casual, but the walk from the parking area involves some light trail terrain and can be damp or sandy, so trail shoes or sturdy sneakers work better than sandals. Bring sunscreen regardless of cloud cover. On foggy mornings UV still penetrates the marine layer, and once the sun comes out on a clear day the reflected light off sand and water adds up quickly. See the dressing in layers guide for a more complete breakdown of how to dress for Bay Area coastal days. Sunglasses, a hat with a brim, and a small daypack to carry shed layers round out a practical kit.

Cold. That is the honest answer. The Pacific Ocean along the Marin coast runs between approximately 50°F and 58°F year-round, with slight warming in late summer. This is the California Current at work: cold water upwells from depth along the Northern California coast, and it does not heat up the way Atlantic beaches or Southern California beaches do. Air temperatures at Muir Beach can be a perfectly pleasant 72°F on a summer afternoon while the water is 54°F. This gap between air and water temperature is one of the defining characteristics of Northern California beaches and why most people do not actually swim here in the conventional sense. Wading is common, and the brave go in, but extended swimming without a wetsuit is uncomfortable for most people regardless of season. Late summer, specifically August and September, brings the warmest ocean temperatures of the year, and that is when the water is most approachable. For the full picture of Bay Area ocean water temperatures by month and location, the Bay Area ocean water temperatures guide has detailed data. The nearby Tennessee Valley Beach has similar water temperature conditions given its position on the same stretch of coast.

The data shows roughly 226 perfect days per year at Muir Beach, which is a high number for a Northern California coastal location and reflects the genuine sunshine potential of this spot when conditions align. Average daily sunshine across the 18-month observation period runs about 9.4 hours per day. The sunniest months are April through August. April 2025 led the dataset with 12.8 hours of sunshine per day, followed closely by May at 12.6 hours and June at 11.2 to 12.4 hours depending on the year. These are genuinely long, bright days. The December-January trough brings the shortest days, down to 6.2 hours of recorded sunshine, and those hours are often partially obscured by cloud cover given the winter rainfall pattern. One useful observation: March 2025 was a pleasant surprise in the dataset, logging 11.1 hours of sunshine per day with a comfort score of 81 and only 0.52 inches of rain. Spring shoulders at Muir Beach can be excellent if you catch a good spell. For a comparison of sunshine and weather patterns in the adjacent watershed, the Muir Woods weather guide is a useful reference given how close the two destinations are.

Almost never. The Mediterranean climate pattern that defines the Bay Area means Muir Beach's summer is essentially dry. June 2024 recorded zero rainfall. July 2024 logged 0.12 inches, and August 2024 had just 0.07 inches for the entire month. June and July 2025 were similarly rain-free. This reliability is one of the things that makes summer the consensus best season: you are not just hoping for good weather, you are planning around a near-certainty. The shift happens in October. October 2024 brought nearly 6 inches of rain, and October 2025 added another 4.84 inches. The rainy season arrives fairly abruptly in the fall, and once November arrives, rain is a regular feature through April. Even within the rainy season, the pattern is storm-driven rather than continuous: a system moves through, drops significant rain over a few days, then clears out for a period of sunshine before the next system arrives. This means there are plenty of good beach days even in winter, just fewer of them and with less predictability. If you are planning a summer visit, weather uncertainty is genuinely not a concern. If you are considering an off-season visit, a three-to-five day weather window is worth checking before you commit.

Muir Beach sits in an interesting position in the local beach hierarchy. It is more sheltered than Rodeo Beach to the south, which faces more direct wind exposure given its position at the mouth of Rodeo Lagoon without the same cove protection. Stinson Beach to the north tends to be warmer and sunnier on good days because it sits in a wider, more southward-facing bay that captures afternoon sun more directly and is slightly more protected from the prevailing northwest wind. On peak summer days, Stinson can run 5 to 8 degrees warmer than Muir Beach. That said, Muir Beach has a quieter character that changes the experience independent of temperature. The cove is small and less developed, which means the crowd dynamics are different and the immediate environment feels more intimate. Tennessee Valley Beach, accessible by trail from the valley, shares a similar exposed coastal character but requires a hike to reach. The Muir Beach Community nearby provides some amenity context for planning a longer visit. For anyone choosing between nearby beaches based on weather alone, Stinson is the warmest option, Rodeo Beach is the most dramatic and windswept, and Muir Beach splits the difference. For a broader look at Bay Area beach options and how to choose based on conditions, the Bay Area beach day trips weather guide covers the trade-offs in useful detail.