Mill Valley Weather
Town • San Francisco Bay Area
Mill Valley climbs from the marshy edge of Richardson Bay into wooded canyons on the southeast slopes of Mount Tamalpais. Downtown, around Lytton Square, sits where Blithedale and Cascade canyons open out, a short walk from Old Mill Park and its creek. Public stairways, lanes, and paths climb the hillsides, and the old scenic railway grade winds up Blithedale Canyon. The course of the Dipsea Race runs from downtown up and over the mountain to the Pacific. It is the town most tied to Mount Tam's trails.
Plan your week
10-Day Forecast
Hour by hour
Hourly Forecast
Current Conditions
Comfort Breakdown
Mill Valley weather today and through the year
It's 54°F at Mill Valley right now (feels like 52°F), with 4 mph wind and a comfort score of 78. Today's forecast high at Mill Valley is 63°F, close to the mid November normal of 62°F. No fog in the forecast for today at Mill Valley. In November, 25% of morning hours here are foggy on average. The best window today is 9 AM to noon, at about 54°F with a 3 mph wind (comfort 60).
September is the warmest month at Mill Valley, with an average high of 73°F. January is the coldest, with an average low of 43°F. December is the wettest month (7.8 in.), out of about 35.8 in. a year. By typical temperature, wind, cloud, humidity, and rain odds, the most comfortable months at Mill Valley are September, July, and August. The best hours are usually 11 AM to 2 PM in September, 11 AM to 2 PM in July, and 11 AM to 2 PM in August.
Mount Tamalpais shields Mill Valley from the ocean to the west, so its fog arrives by a back door. In summer, marine air that streams through the Golden Gate and over the low ridges of the Marin Headlands spreads up Richardson Bay and through Tamalpais Valley. Low clouds often cover the bayfront neighborhoods in the morning and pull back by midday. Muir Beach, on the ocean side of the ridge, may stay gray all day.
Forecast updated November 15, 2026 at 4:00 AM PST. Climate figures come from NOAA 1991-2020 normals. Hourly patterns come from NOAA's HRRR hourly analysis from September 2014 to April 2026.
What to expect at Mill Valley in the next few days
No active National Weather Service alerts for this location.
Fog
No fog in the forecast for today at Mill Valley. In November, 25% of morning hours here are foggy on average.
Best time to go
The best window today is 9 AM to noon, at about 54°F with a 3 mph wind (comfort 60).
Best day this week
Of the next 7 days, Friday looks best for Mill Valley, with a 60°F high and midday comfort near 78. Today looks weakest (48).
Rain
Next good chance of rain: today (83%, about 0.56 in.).
Live weather map
Weather around Mill Valley right now
Overcast and 54° at Mill Valley right now.
About the live weather map for Mill Valley
The map centers on Mill Valley and stacks fog, satellite clouds, and precipitation radar on one view. Clouds come from the GOES-West satellite and rain from NOAA radar, and both show current conditions. Fog comes from our HRRR-based fog model, and the slider steps through its forecast for the next 12 hours.
Dots mark nearby places with their current temperature, colored by comfort score. Use the layer buttons to turn any layer off, or open the full map for every destination in the region.
Nearby Temperature Comparison
Conditions at nearby San Francisco Bay Area destinations
Tip: Bay Area temperatures can change by 20 to 30°F over a short distance because of microclimates.
Mill Valley vs nearby places
Typical summer conditions compared with Mill Valley, from the same NOAA HRRR hourly record. The list shows the closest places, then nearby places whose climate differs the most.
| Place | Distance | Summer afternoons | Morning fog | Afternoon wind | Compared with Mill Valley |
|---|---|---|---|---|---|
| Muir Woods National Monument | 1.7 mi | -2°F | 24% | 9 mph | a very similar climate |
| Larkspur | 2 mi | +3°F | 18% | 5 mph | a very similar climate |
| Corte Madera | 2.3 mi | +3°F | 14% | 6 mph | a very similar climate |
| Rodeo Beach | 5.1 mi | -20°F | 48% | 13 mph | about 20°F cooler on summer afternoons and more summer morning fog (48% vs 19% of morning hours) |
| Ocean Beach | 10.3 mi | -19°F | 49% | 11 mph | about 19°F cooler on summer afternoons and more summer morning fog (49% vs 19% of morning hours) |
| Pacifica | 20.4 mi | -20°F | 56% | 9 mph | about 20°F cooler on summer afternoons and more summer morning fog (56% vs 19% of morning hours) |
Places with a climate like Mill Valley's
- Visitacion Valley (15 mi away): similar temperatures through the year
- Point Reyes Station (18 mi away): similar temperatures through the year
- South San Francisco (19 mi away): similar temperatures through the year
Climate Dashboard
Current conditions vs. NOAA normals and recent destination baseline
What the Mill Valley climate comparisons mean
These cards compare recent conditions at Mill Valley with the available local baseline. Temperature and year-to-date rainfall use long-term normals when available. Fog, sunshine, wind, and comfort use the matching recent or modeled baseline identified on each card.
Positive and negative differences describe how Mill Valley departs from its own usual pattern. They should not be read as a direct comparison with another city or as a forecast beyond the period shown.
Mill Valley weather by month
September is the warmest month at Mill Valley, with an average high of 73°F. January is the coldest, with an average low of 43°F. December is the wettest month (7.8 in.), out of about 35.8 in. a year. Morning fog peaks in December, when fog or low cloud covers 39% of the hours from 6 to 10 AM. July has the clearest middays, with clouds covering about 14% of the sky from 11 AM to 3 PM.
By typical temperature, wind, cloud, humidity, and rain odds, the most comfortable months at Mill Valley are September, July, and August. The best hours are usually 11 AM to 2 PM in September, 11 AM to 2 PM in July, and 11 AM to 2 PM in August.
| Month | Avg high | Avg low | Rain | Rainy days | Morning fog | Midday cloud | Afternoon wind | Daylight | Comfort |
|---|---|---|---|---|---|---|---|---|---|
| Jan | 56°F | 43°F | 6.8 in | 11 | 33% | 37% | 5 mph | 9.8 h | 37 |
| Feb | 58°F | 44°F | 6.8 in | 11 | 18% | 27% | 6 mph | 10.7 h | 46 |
| Mar | 61°F | 45°F | 5.0 in | 9 | 19% | 31% | 7 mph | 11.9 h | 52 |
| Apr | 63°F | 46°F | 2.3 in | 6 | 13% | 25% | 8 mph | 13.2 h | 69 |
| May | 65°F | 49°F | 1.1 in | 4 | 14% | 24% | 9 mph | 14.2 h | 79 |
| Jun | 70°F | 51°F | 0.3 in | 2 | 14% | 15% | 8 mph | 14.8 h | 86 |
| Jul | 72°F | 53°F | 0.0 in | 1 | 21% | 14% | 9 mph | 14.5 h | 88 |
| Aug | 73°F | 54°F | 0.1 in | 1 | 21% | 17% | 8 mph | 13.6 h | 88 |
| Sep | 73°F | 54°F | 0.1 in | 2 | 19% | 17% | 7 mph | 12.3 h | 91 |
| Oct | 70°F | 51°F | 1.6 in | 5 | 20% | 20% | 6 mph | 11.1 h | 84 |
| Nov | 62°F | 47°F | 3.9 in | 8 | 25% | 25% | 5 mph | 10.0 h | 68 |
| Dec | 56°F | 43°F | 7.8 in | 12 | 39% | 40% | 6 mph | 9.5 h | 35 |
Morning fog is the share of hours from 6 to 10 AM with fog or low cloud. Midday cloud is the average from 11 AM to 3 PM, and afternoon wind is the average from 1 to 5 PM. The highlighted rows are the most comfortable months.
What makes Mill Valley's weather different
When the fog burns off
3 PMwhen December fog usually thins (45% foggy at 8 AM)
Fog or low cloud covers Mill Valley in 45% of 8 AM hours in December, the foggiest month. It usually thins to a third of that by 3 PM, but 15% of mid-afternoon hours are still foggy. April mornings are the least foggy (13%).
When the wind picks up
noonwhen afternoon wind builds, April–September
From April through September, wind at Mill Valley typically builds after noon. In May it peaks around 3 PM, averaging 9 mph with 4% of those hours windy, while mornings average 5 mph.
Microclimate
−20°FRodeo Beach, 5.1 mi away, on summer afternoons
Rodeo Beach, 5.1 miles away, runs about 20°F cooler than Mill Valley on summer afternoons. It also has far more summer morning fog, 48% of morning hours compared with 19%.
Daylight
9.5–14.8 hof daylight, Dec to Jun
Days at Mill Valley range from about 9.5 hours in December to 14.8 hours in June. In mid-June the sun sets around 8:34 PM, and in mid-December around 4:55 PM.
Seasons at Mill Valley
- Warm seasonJul 4 – Oct 3 · highs 71°F+
The warm season lasts about 3 months, from Jul 4 to Oct 3, when the average high is 71°F or warmer. Highs peak around Sep 8 at about 73°F.
- Cool seasonDec 1 – Feb 24 · highs 59°F or lower
The cool season runs from Dec 1 to Feb 24, when the average high is 59°F or lower. The coldest nights come around Jan 8, with an average low near 43°F.
- Rainy seasonOct 26 – Apr 19 · 89% of the year's rain
The rainy season runs from Oct 26 to Apr 19, when a day has at least a 20% chance of measurable rain. That stretch brings 89% of the year's rain.
The dark line marks today. Season dates come from the smoothed daily NOAA 1991-2020 normals. Counting from Oct. 1, a typical year has its first inch of rain by Oct 19 and half of its annual total by Jan 21.
Days per year and extremes (Nov 1, 2024 to Oct 31, 2026)
This record runs from Nov 1, 2024 to Oct 31, 2026. Over this record, Mill Valley averaged 10 days a year at 90°F or hotter and no freezing nights. It averaged 21 days a year with at least half an inch of rain and 1 afternoon with wind of 20 mph or more at 2 PM. About 114 mornings a year had 3 or more hours of fog or low cloud.
In the same record, the hottest day was Sep 9, 2026 (100°F) and the coldest night was Feb 20, 2026 (36°F). The wettest day was Feb 16, 2026 (2.70 in.), and the strongest 2 PM gust was 46 mph on Mar 12, 2025.
- 10days at 90°F or hotter
- 0nights at or below freezing
- 21days with ½ in. of rain or more
- 1afternoon with 20+ mph wind
- 114mornings with 3+ hours of fog or low cloud
- Hottest day100°FSep 9, 2026
- Coldest night36°FFeb 20, 2026
- Wettest day2.70 inFeb 16, 2026
- Strongest 2 PM gust46 mphMar 12, 2025
What shapes Mill Valley's weather
Mill Valley's weather changes between the bay flats and the canyons. The flat neighborhoods near the bay get the afternoon breeze off Richardson Bay. The canyon streets up Blithedale, Cascade, and Throckmorton sit under tall trees and steep slopes that keep them shaded and damp. They stay cooler in the afternoon than the open flats along Miller Avenue.
In winter, storms that run into Mount Tamalpais drop heavy rain on its slopes, and runoff pours down the canyon creeks into the low ground by the bay. The year's highest tides are called king tides. When runoff meets one, the city says lower Miller Avenue, Camino Alto, and the Sycamore Park neighborhood can flood. Tides can also block the Manzanita ramps to Highway 101.
Tips for visiting Mill Valley
Watch for tide flooding near Manzanita
High king tides can limit or block the Manzanita on- and off-ramps at Highway 101. Never drive through standing water.
Climb the public stairways
The city maintains a network of public steps, lanes, and paths. A printed map is sold at the Mill Valley Community Center.
Walk the old railroad grade
A self-guided walk with 13 stops follows the bed of the scenic railway that ran up Blithedale Canyon from 1896 to 1930.
Head uphill to escape summer fog
On foggy summer mornings, the upper slopes of Mount Tamalpais above town often rise into sunshine above the marine layer, the low ocean cloud that fills the bayfront.
Catch the bay breeze at Bayfront Park
Bayfront Park, on Richardson Bay off Sycamore Avenue, has a walking trail and a big open lawn. It gets the full afternoon breeze off the water, so bring a layer.
Mill Valley through the seasons
- Spring (March–May)
- Creeks still run from the winter rains and the canyon trails stay damp and shady. Morning fog starts returning to the bayfront by late spring.
- Summer (June–August)
- Summer mornings can start foggy near the bay, with sun by midday in most of town. The redwood canyons stay cool on the warmest afternoons.
- Fall (September–October)
- September is the warmest month in Mill Valley. Wooded hillsides make fire weather a real concern, so sign up for the city's emergency alerts and know your way out of the canyons.
- Winter (November–February)
- Winter is storm season and the wettest time of year. King tides combined with heavy runoff can flood lower Miller Avenue and the Sycamore Park area. Steep slopes face a higher risk of mudslides in very wet winters.
Activities and the weather that matters
- Stairway and canyon walks: The shaded canyons are the place to be on hot days. Wet steps and leaf litter get slick after rain.
- Running or hiking the Dipsea: The Dipsea course runs about 7 miles up and over Mount Tamalpais to the Pacific, so you can start in sun and finish in coastal fog.
- Downtown around Lytton Square: A mild afternoon is best, once any morning fog has lifted. The square is sheltered from most of the bay wind.
- Picnics at Old Mill Park: Creekside shade keeps it cool in summer. After heavy winter rain the creek runs high and fast.
Official sources and current conditions
- City of Mill Valley: El Niño 2026-2027 flooding and storms
- City of Mill Valley: parks
- City of Mill Valley: emergency preparedness
Numbers on this page come from NOAA data. The text draws on the official sources linked above.
Historical Climate Data
Long-term weather patterns and climate data
Data sources: Recent temperatures come from NOAA URMA and recent precipitation from NOAA Stage IV. Fog, cloud, wind, humidity, and sunshine come from NOAA HRRR, and long-term baselines from NOAA 1991-2020 climate normals.
Climate Overview
Based on NOAA 30-year temperature/rain normals (1991-2020) with recent fog/sun baseline
🌟 Best Months to Visit
⚠️ Challenging Months
Monthly Breakdown
| Month | Comfort | High/Low | ☀️ Sun | 🌫️ Fog | 💧 Rain | Perfect |
|---|---|---|---|---|---|---|
| November 2024 | 76 | 61.3° / 48.3° | 6.2h | 7d | 6.53" | 16 |
| December 2024 | 66 | 57.5° / 47.2° | 4.4h | 16d | 10.47" | 10 |
| January 2025 | 81 | 58.6° / 43.6° | 6.7h | 8d | 0.26" | 18 |
| February 2025 | 74 | 59.6° / 45.1° | 6.6h | 8d | 9.94" | 15 |
| March 2025 | 77 | 59.9° / 45.8° | 7.7h | 5d | 2.94" | 16 |
| April 2025 | 89 | 64.7° / 47° | 10.3h | 3d | 0.35" | 25 |
| May 2025 | 94 | 73.2° / 50.7° | 12.3h | 1d | 0.14" | 31 |
| June 2025 | 94 | 72.2° / 50.5° | 12.5h | 4d | 0" | 29 |
| July 2025 | 92 | 70.5° / 52.8° | 11.6h | 7d | 0" | 29 |
| August 2025 | 96 | 80.2° / 55.6° | 11.5h | 1d | 0" | 31 |
| September 2025 | 90 | 75.7° / 58.1° | 9.3h | 3d | 0.12" | 24 |
| October 2025 | 86 | 70° / 53.8° | 7.7h | 9d | 0.71" | 24 |
| November 2025 | 74 | 61.8° / 50.9° | 5.6h | 14d | 3.85" | 12 |
| December 2025 | 58 | 52.8° / 45.5° | 4.1h | 22d | 6.1" | 4 |
| January 2026 | 75 | 59.2° / 46.9° | 6.3h | 10d | 6.13" | 16 |
| February 2026 | 75 | 62.1° / 47.9° | 6.3h | 6d | 7.84" | 16 |
| March 2026 | 94 | 75.5° / 53° | 9.6h | 2d | 0.05" | 30 |
| April 2026 | 86 | 65.9° / 49.2° | 9.3h | 3d | 3.6" | 22 |
| May 2026 | 90 | 69.8° / 51.6° | 11.3h | 8d | 0.66" | 29 |
| June 2026 | 90 | 73.3° / 53.5° | 11.9h | 8d | 0" | 27 |
| July 2026 | 92 | 77° / 54.7° | 11.6h | 4d | 0" | 30 |
| August 2026 | 90 | 74.2° / 54.4° | 10.5h | 7d | 0.02" | 27 |
| September 2026 | 92 | 75.6° / 55° | 10h | 3d | 0.3" | 27 |
| October 2026 | 90 | 75.3° / 53.2° | 8.5h | 2d | 0.3" | 28 |
Climate Trends
Average Temperature by Month
About the Mill Valley climate charts
The temperature chart compares average monthly highs and lows at Mill Valley, showing both the seasonal cycle and the typical day-to-night range. The comfort chart summarizes how often the combined weather pattern is favorable rather than judging temperature alone.
Precipitation shows the total recorded or modeled rainfall for each month at Mill Valley. Sunshine compares average bright-sky hours with the daylight available, while fog shows the average number of morning fog or low-cloud hours per day. Switch between the chart tabs to compare the same months across each measure.
Hourly Temperature, Fog, Wind, Cloud Cover, and Solar Radiation Patterns
Average local hour by month from 2014-09-30 to 2026-04-30
- Temperature: At Mill Valley, the warmest typical hour is 4 PM in August (79°F). The coldest is 7 AM in February (46°F).
- Fog: Fog or low cloud covers Mill Valley in 45% of 8 AM hours in December, the foggiest month. It usually thins to a third of that by 3 PM, but 15% of mid-afternoon hours are still foggy. April mornings are the least foggy (13%).
- Wind: From April through September, wind at Mill Valley typically builds after noon. In May it peaks around 3 PM, averaging 9 mph with 4% of those hours windy, while mornings average 5 mph.
- Cloud Cover: July middays are the clearest at Mill Valley (14% average cloud cover), and December middays are the cloudiest (40%).
- Solar Radiation: The strongest typical sun at Mill Valley comes at 1 PM in July, averaging 977 W/m².
How to read the hourly heatmaps for Mill Valley
This heatmap shows how average temperature at Mill Valley changes by hour and month. Read left to right for the seasons and top to bottom for the time of day. Warmer colors mark the usual afternoon peaks, and cooler colors show overnight and winter lows.
This heatmap shows when fog or low cloud is most likely at Mill Valley. Darker cells mark the months and hours when fog has been most common. They help separate overnight or morning fog from cloud that tends to linger into the afternoon.
This heatmap shows the typical hourly wind pattern at Mill Valley through the year. It makes recurring afternoon wind, calmer overnight periods, and seasonal changes easier to compare than a single daily wind value.
This heatmap shows average cloud cover at Mill Valley for every month and hour. Use it to see whether cloudiness is mainly an overnight and morning pattern or commonly persists during the part of the day you plan to visit.
This heatmap shows the average solar radiation reaching Mill Valley by month and hour. Brighter cells indicate the strongest typical sun, while muted cells can reflect nighttime, shorter winter days, cloud cover, smoke, or terrain shading.
Each cell combines one month with one local hour. Hover over or focus on a cell for its value and sample coverage. The red marker shows the current month and hour.
How recent months compared at Mill Valley
- October 2026 recap: October 2026 at Mill Valley averaged a high of 75°F, 5°F warmer than the 1991-2020 normal of 70°F. It brought 0.30 in. of rain, compared with a normal of 1.65 in.
- Rain year: The 2025-26 rain year (Oct. 1 to Sep. 30) brought 29.3 in. of rain to Mill Valley, 82% of the 35.8 in. normal.
Location Details
Mill Valley weather questions
Everything you need to know about weather and visiting Mill Valley
What is the weather like at Mill Valley today?
It's 54°F at Mill Valley right now, with a comfort score of 78 (great). Today's forecast high at Mill Valley is 63°F, close to the mid November normal of 62°F. The best window today is 9 AM to noon, at about 54°F with a 3 mph wind (comfort 60).
What is the best month to visit Mill Valley?
By typical temperature, wind, cloud, humidity, and rain odds, the most comfortable months at Mill Valley are September, July, and August. The best hours are usually 11 AM to 2 PM in September, 11 AM to 2 PM in July, and 11 AM to 2 PM in August. The warm season lasts about 3 months, from Jul 4 to Oct 3, when the average high is 71°F or warmer. Highs peak around Sep 8 at about 73°F.
What are the warmest and coldest months at Mill Valley?
September is the warmest month at Mill Valley, with an average high of 73°F. January is the coldest, with an average low of 43°F.
When does the fog burn off at Mill Valley?
Fog or low cloud covers Mill Valley in 45% of 8 AM hours in December, the foggiest month. It usually thins to a third of that by 3 PM, but 15% of mid-afternoon hours are still foggy. April mornings are the least foggy (13%).
When is it windiest at Mill Valley?
From April through September, wind at Mill Valley typically builds after noon. In May it peaks around 3 PM, averaging 9 mph with 4% of those hours windy, while mornings average 5 mph.
How much rain does Mill Valley get?
December is the wettest month (7.8 in.), out of about 35.8 in. a year. The rainy season runs from Oct 26 to Apr 19, when a day has at least a 20% chance of measurable rain. That stretch brings 89% of the year's rain. The 2025-26 rain year (Oct. 1 to Sep. 30) brought 29.3 in. of rain to Mill Valley, 82% of the 35.8 in. normal.
How does Mill Valley weather compare with Rodeo Beach?
Rodeo Beach, 5.1 miles away, runs about 20°F cooler than Mill Valley on summer afternoons. It also has far more summer morning fog, 48% of morning hours compared with 19%.
What kind of place is Mill Valley?
Mill Valley climbs from the marshy edge of Richardson Bay into wooded canyons on the southeast slopes of Mount Tamalpais. Downtown, around Lytton Square, sits where Blithedale and Cascade canyons open out, a short walk from Old Mill Park and its creek. Public stairways, lanes, and paths climb the hillsides, and the old scenic railway grade winds up Blithedale Canyon. The course of the Dipsea Race runs from downtown up and over the mountain to the Pacific. It is the town most tied to Mount Tam's trails.
What is Mill Valley weather like in November?
November at Mill Valley averages a high of 62°F and a low of 47°F, with 3.9 in. of rain over about 8 rainy days. About 25% of morning hours are foggy. Afternoon wind averages 5 mph.
More about Mill Valley weather
Guides that explain the weather here and nearby
Data sources and methods
- Monthly temperatures and precipitation: NOAA 1991-2020 normals.
- Fog, cloud, wind, sun, and comfort by hour and month: NOAA's HRRR hourly analysis from September 2014 to April 2026.
- Daily records and recent months: NOAA URMA and HRRR analyses, plus NOAA Stage IV precipitation.
- Nearby comparisons and regional rankings use the same hourly HRRR summaries for every destination in the region.
- Alerts: National Weather Service. Tides and ocean temperature: NOAA CO-OPS, where shown.
- All statements on this page are computed from these datasets, apart from the “What shapes the weather” guide, which cites its sources inline.
- City of Mill Valley, El Niño 2026-2027 Flooding and Storms (accessed 2026-10-27)
- City of Mill Valley, Parks (accessed 2026-10-27)
- City of Mill Valley, Steps, Lanes and Paths (accessed 2026-10-27)
- City of Mill Valley, Emergency Preparedness (accessed 2026-10-27)
- Visit Marin, Mill Valley (accessed 2026-10-27)
- Visit Marin, Mountain Railroad Walk: a self-guided walk in Mill Valley (accessed 2026-10-27)
- California State Parks, Mount Tamalpais State Park map and park information sheet (accessed 2026-10-27)
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