How far to the sun? (San Jose, San Francisco: live, vs, beach)

[Isebiel]

Not an astronomy question.

Assuming it's the foggiest fog time in Fog City, (qhen is that, winter?) how far inland would someone likely have to go to reach sunshine? Or is there some other easier way to find a sunny microclimate?

Locales in reach of public transit would be best.

Thanks!

[BMW3series]

Only half of San Francisco is usually covered by fog during the summer. The fog rolls in from the Pacific Ocean late late at night, covering most of the city, and then retreats back early in the morning leaving the Eastern side of the city, fogless.

[sonarrat]

Quite often, only a block or two. And the foggiest time in SF is early summer. Late summer it usually clears up.

[BayAreaHillbilly]

Originally Posted by Isebiel

Not an astronomy question.

Assuming it's the foggiest fog time in Fog City, (qhen is that, winter?) how far inland would someone likely have to go to reach sunshine? Or is there some other easier way to find a sunny microclimate?

Locales in reach of public transit would be best.

Thanks!

There are different types of fog. The fog that affects the coast is called advection fog and results from somewhat warm and very moist air being cooled by the cold ocean. That is more common in the summer because the air carried by the prevailing wind is warmer (holding more moisture) during the summer.

There is another type of fog called radiation fog. That results from rising moist air near the ground, expanding and cooling, especially at night, as the warmth (Infra Red energy) in the soil radiates upward into space. A vernacular term for this type of fog is Tule Fog. This type of fog affects inland areas and very rarely affects the bayside areas and even more rarely affects the outer lands and Coastside.

Bottom line - in summer it can be foggy in Daly City and 90 F in Walnut Creek. In winter, in between rains, it can be 65 or 70 F in Daly City and 45F with Tule Fog in Walnut Creek. Further inland, in places like Vacaville or Tracy, they even get ice fog in the winter during the coldest days!

[mayorhaggar]

Out by the beach it can get foggy sometimes to the point where you can't see to the next block, but in other parts of SF or the East Bay the fog is mainly just low cloud cover. Typically the pattern is that in the morning it's very cloudy from the beach out to Berkeley and Oakland, and it's chilly, like 55F around 8AM even in July or August. Then later in the day the cloud cover burns off and/or breaks up and it gets sunnier and warmer. Like yesterday it was gray and cloudy in Oakland as usual, and driving over the Bay Bridge yesterday you could barely see Treasure Island or the top of the bridge span, and you couldn't see Coit Tower at all. Then around 10am to 12pm the clouds burn off and the eastern part of SF gets to around 60-65. The NE part of SF is usually sunny but it's near the water so it's always very windy which keeps temps down. The Mission is warmer and less windy, especially the eastern part (which unfortunately is the grimiest and most crime-ridden part) but usually doesn't get over 70 unless there's a heat wave. Oakland can sometimes stay chilly and windy but usually the wind dies down later in the day, yesterday it was around 75 or so and felt quite warm.

If you want warmer weather than that (like 80's and 90's) I would look either to areas over the Berkeley/Oakland hills like Walnut Creek, or on the Peninsula south of Millbrae or San Mateo. Once you get far enough from the chilly Pacific things heat up.

In winter I'd say the cloud cover is higher up and you're more likely to get sunny mornings, but it's usually so chilly and windy that it doesn't really matter that the sun is out. But you can also get gray skies with rain for days on end--a full week of steady rain isn't uncommon in winter. Also it's a bit warmer towards the coast compared to the more inland areas, Walnut Creek can dip into the 30's and 20's when SF doesn't go below 45, and Oakland can definitely be about 5 degrees or so colder than SF, especially in the morning.

Also September and sometimes October are warmer than June-August, the winds shift and the fog goes away and it's sunny and warmer, then at some point it starts cooling off a bit.

[tanglenet]

Usually...East Bay, starting with Orinda and further east. Peninsula, Burlingame and further south. North Bay, San Rafael and further north.

[tstieber]

Originally Posted by BayAreaHillbilly

Bottom line - in summer it can be foggy in Daly City and 90 F in Walnut Creek. In winter, in between rains, it can be 65 or 70 F in Daly City and 45F with Tule Fog in Walnut Creek. Further inland, in places like Vacaville or Tracy, they even get ice fog in the winter during the coldest days!

I grew up in Walnut Creek and remember days like that in the winter. However, keep in mind that the summer pattern you describe (65 and foggy in Daly City, 90 in WC) reflects average and typical sky conditions and temperatures for summer, while the winter pattern you describe is much more rare. The entire Bay Area ranges from about 53 in Santa Rosa to the north, to about 60 in Gilroy or south San Jose in January, which is a small difference, while in summer, the range is much larger from the low 60s to low 90s. The average difference between Walnut Creek's and Daly City's winter daytime highs is only about 2 degrees (55 vs 57), and when the weather pattern is active, Daly City's blustery winds can make it feel much colder than being inland, where it's calmer. But when those inland fog/coastal warmth days do happen, they're pretty interesting. The Central Valley does get a lot more tule fog than the Bay Area's inland valleys too.

I remember being a kid in the winter of 1985, we had 21 straight days of tule fog in Contra Costa County, and it was a record. It was pretty weird, and it kept getting colder and colder every day, because the sun just wouldn't come through. In SF, it was in the 60s, and up on Mt. Diablo, it was in the 70s, which made for a fun but trippy Christmas Eve daytrip with the family. Down in the valley, we were starting to see high temps of about 38 to 39 degrees though, and at night, it was exactly the same temperature, no variation from day to night. This was really great weather for crops though -- lots of chilling hours below 45F for dormant stone fruit, but well above freezing for citrus.

[tstieber]

To the OP, your fastest bet for sunny AND warm weather is to cross the Golden Gate Bridge into Marin County and get at least to Mill Valley, although Corte Madera and San Rafael are usually noticeably warmer and often hot. Today's forecast calls for high 70s in San Rafael. If you want to take BART, head inland to Orinda and beyond. Walnut Creek was about 90 yesterday, and it's supposed to be about the same today.

[18Montclair]

Usually in the winter, its foggier in the inland valleys than it is around the Bay.

Otherwise, in the summer fog usually burns off around noon in Downtown and maybe a little earler around the Bay.

And many mornings don't even have fog.

Something else. Whenever there isnt fog for 2 consecutive mornings, I notice smog and haze begin to develop on the 3rd morning and then greatly increase every day until the wind and fog returns.

[mayorhaggar]

Current temps right now listed on sfgate.com at 3:30pm pacific, I'd say this is pretty typical of what you see reported in summer:

San Francisco: 65
Santa Rosa: 74
Napa: 78
Concord: 90
Oakland: 69
Livermore: 89
Hayward: 75
San Carlos: 68
Palo Alto: 76
San Jose: 82
Fairfield: 84
Mountain View: 80
Monterey: 64