Across the year, daylight in San Francisco ranges from about 9h 23m in December to 14h 37m in June — a 5h 14m swing that shapes sleep, mood and training rhythms. From roughly December through February, the sun sits too low for much vitamin D production.
San Francisco is part of the San Francisco Bay Area; the nearest other Live10X guide is San Jose, about 42 miles away.
San Francisco by the numbers
- County
- San Francisco County
- Climate
- Mediterranean
- Elevation
- near sea level
- Latitude
- 37.8°N
- Shortest day
- 9h 23m
- Longest day
- 14h 37m
- Vitamin D winter
- December through February
- Metro
- Bay Area
At a glance
San Francisco at a glance
- Top local priority in San Francisco: year-round outdoor movement.
- Daylight swings from about 9h 23m to 14h 37m across the year — anchor your wake time and get morning light.
- Sunlight is too weak for much vitamin D production from roughly December through February; a blood test shows where you stand.
- Use Golden Gate Park and the Presidio for easy, regular outdoor movement.
Climate & lifestyle
What living in San Francisco means for your health
San Francisco has a Mediterranean-type climate: mild, damp winters and long, dry summers with plenty of sunshine. It's one of the easiest climates in the country for year-round outdoor training — the main watch-outs are summer UV, midsummer heat inland and smoky days in wildfire season.
- year-round outdoor movement
- daily sun protection
- protecting sleep and focus from long screen days
- air-quality awareness in fire season
Light, sleep & vitamin D
Daylight in San Francisco across the year
9h 23m
Shortest day (December)
14h 37m
Longest day (June)
~3 mo
Low-UVB “vitamin D winter”
At about 37.8°N, San Francisco sees a 5h 14m swing in day length between the solstices. Research suggests winter UVB is too weak for meaningful vitamin D production for roughly three months a year. That's roughly December through February. Bright morning light helps anchor your body clock, and a simple blood test shows whether your vitamin D is where it should be.
Calculated from latitude using standard solar formulas and published latitude research. How we calculate this
Local wellness trends
Wellness trends in San Francisco
Year-round outdoor training
Mild weather means San Francisco's runners, cyclists and outdoor bootcamps rarely need an off-season.
Executive & founder health
San Francisco's tech community drives demand for focus, energy and preventive screening — and for protecting sleep from screen-heavy workdays.
Food culture & personalized nutrition
San Francisco's food scene puts farmers markets and diverse cuisines within reach, fueling interest in gut health and nutrigenomics.
Coastal trails & ocean swims
Coastal trail runs and cold ocean swims connect San Francisco's residents to the Pacific.
Local health optimization resources
Places to move, recover and eat well in San Francisco
- ParkGolden Gate ParkGreen space for walks, bodyweight workouts and time in nature.
- Parkthe PresidioGreen space for walks, bodyweight workouts and time in nature.
- Waterfrontthe Crissy Field promenadeWaterfront paths for easy cardio and outdoor time.
Testing
At-home wellness genetic testing
Available throughout San Francisco: order online, collect a sample at home and review results with a qualified professional.
Learn more about at-home wellness genetic testingHealthcare
Preventive care & baseline labs
Primary care clinicians in San Francisco County can order baseline labs — such as a lipid panel, HbA1c, vitamin D and B12 — useful context for any wellness plan.
Learn more about preventive care & baseline labsNutrition
Farmers markets & local food
San Francisco's food scene makes it easier to eat 30+ different plants a week — shop seasonal produce at local farmers markets.
Learn more about farmers markets & local foodRecovery
Sauna & recovery studios
Gyms, spas and recovery studios around San Francisco offer sauna and cold plunge — look for clean facilities and clear safety guidance.
Learn more about sauna & recovery studiosSeasonal playbook
A seasonal wellness playbook for San Francisco
- Winter: mild temperatures keep outdoor training on track — the rainy season rarely derails a well-planned week.
- Summer: strong sun and dry heat inland — train early, use sunscreen and hydrate well.
- Late summer and fall: check air-quality forecasts during wildfire season and move hard workouts indoors on smoky days.
- Winter light: with only about 9h 23m of daylight in December, get outside in the morning and keep indoor lighting bright during the day.
Recommended reading
The most relevant guides for San Francisco residents
FAQ
San Francisco wellness FAQs
Where can I get wellness genetic testing in San Francisco?
Is San Francisco's climate good for year-round training?
Can you get enough vitamin D from the sun in San Francisco?
How do seasonal daylight changes in San Francisco affect sleep?
Where can you walk, run or train outdoors in San Francisco?
How can busy professionals in San Francisco protect energy and focus?
The bottom line
Living well in San Francisco means working with its mild, wet winters and dry, sunny summers: year-round outdoor movement, daily sun protection and protecting sleep and focus from long screen days. Add the fundamentals — consistent sleep, daily movement, strength training and a whole-food diet — and personalize with the wellness assessment and at-home testing.
