San Francisco
Vitamin D from the sun in San Francisco
9 months of sun
In San Francisco you can synthesize vitamin D from February to October.
From November to January synthesis isn't possible — this is when a supplement can help.
San Francisco: we'll tell you the days you can make vitamin D.
Loading notifications…Today's sun in San Francisco
Today's sunrise, sunset, golden hour and day length.
Year-round profile in San Francisco
Daily hours with enough sun to synthesize vitamin D across the year.
Seasonal windows
- March: between 10:00 and 16:00, about 9 min for 1000 IU.
- June: between 09:00 and 17:00, about 5 min for 1000 IU.
- September: between 10:00 and 16:00, about 8 min for 1000 IU.
- December: synthesis isn't possible.
Estimated for Fitzpatrick type III skin, arms and face exposed, clear sky.
When to supplement in San Francisco
During the months without solar synthesis, vitamin D comes only from food or a supplement. It is usually taken as D3, often with magnesium — which the body needs to activate it — and vitamin K (as K2), which contributes to the maintenance of normal bones.
More about supplementsSunrise and sunset by month in San Francisco
How sunrise, sunset and day length change over the year.
| Month | Sunrise | Sunset | Day length |
|---|---|---|---|
| 07:24 | 17:14 | 9 h 49 min | |
| 07:02 | 17:46 | 10 h 44 min | |
| 07:24 | 19:15 | 11 h 51 min | |
| 06:36 | 19:44 | 13 h 08 min | |
| 06:00 | 20:12 | 14 h 11 min | |
| 05:47 | 20:33 | 14 h 46 min | |
| 05:59 | 20:31 | 14 h 32 min | |
| 06:26 | 20:02 | 13 h 36 min | |
| 06:53 | 19:15 | 12 h 22 min | |
| 07:21 | 18:29 | 11 h 08 min | |
| 06:53 | 16:57 | 10 h 04 min | |
| 07:19 | 16:52 | 9 h 34 min |
Approximate values for mid-month (the 15th).
Frequently asked questions about vitamin D in San Francisco
- Can I get vitamin D from the sun in winter in San Francisco?
- In San Francisco you can synthesize vitamin D from February to October.
- How many minutes of sun do I need in San Francisco?
- In summer, about 9 minutes with arms and face exposed is enough for 1000 IU (Fitzpatrick type III skin, clear sky).
- What time does the sun rise and set in San Francisco?
- It shifts with the seasons: in June the sun rises around 05:47 and sets around 20:33; in December it rises around 07:19 and sets around 16:52.
- What is the longest day of the year in San Francisco?
- Longest day: June, with about 15 h of daylight. Shortest day: December, with about 10 h.
- When is golden hour in San Francisco?
- It's roughly the last hour before sunset: in June it starts around 19:54 and in December around 16:11.