Is the Peninsula microclimate significantly cooler than South Bay? (San Jose: for sale, 2014)

[NapaCab]

We've been living in the South Bay for the past 4 years. While I've been enjoying the El Niño rains and cooler temperatures this winter, I am anticipating with dread another hot summer.

Where does the 'fog belt' start and end exactly? I like San Francisco's foggy microclimate on the Western side of the city where the Zoo is, for example, but living there would mean a hellish commute. Is the climate still cool and foggy further down the Bay e.g. around San Mateo, San Carlos, Belmont? Data I can find suggests about a 75-82F average summer temperature for San Mateo, a little cooler than where I am but not much. I was in San Carlos at the weekend and it didn't feel much cooler than where we live in the South Bay. It seemed greener though and with more tree cover, which is something. Would it be worth moving up from the South Bay to the Peninsula for climate alone or is it not significantly cooler?

[MountainHi]

This shows you a map of where the fog is in the summer




What Exactly is Fog?

[ketch89]

A little historical anecdote that might help - after the gold rush ended, wealthy San Franciscans built mansions in the Hillsborough and Burlingame area specifically to escape the cold and fog further north. If you want ocean influence, you need to be somewhere that the ocean breeze isn't blocked by mountains. Personally, I consider the "fog belt" to be Millbrae and north. I worked in San Carlos for a while and it was really hot in the summer, definitely not in the fog belt at all.

[HockeyMac18]

Originally Posted by MountainHi

This shows you a map of where the fog is in the summer




What Exactly is Fog?

Some of the info is a bit off - mainly what causes the fog (the air being cooled by the ocean/upwelled water cool water, not really anything to do with air from Alaska) and why it warms up as you move south on the peninsula (it has nothing to do with distance from SF, but rather is due to cooler pacific air being blocked by the hills/Santa Cruz mountains).

But this does a good job of illustrating where the fog generally sits.

As others mentioned, I generally agree that the fog line is around Milbrae/San Bruno. There is a gap between the hills above San Bruno and San Bruno mountain where the air rushes in (bringing the fog with it).

That said, when the fog is most intense in summer, it can squeak through the San Mateo gap (which 92 traverses) from Half Moon Bay. And on these days the mid peninsula can be covered for a bit (usually burns off by late morning). I live in downtown San Mateo and enjoy these days.

Regarding temperatures of San Mateo compared to the south bay, it can be 5-15 degrees cooler (depending on where in the south bay). I find that's usually enough for my comfort (I find most of the south bay to be too hot for me). The differences are most dramatic in the summer months when the microclimates are dominant. In the winter, differences in temps between the regions are much smaller.

I think mid peninsula offers weather that is comfortable to most people (warm but not hot), and you can easily move up and down the peninsula to get different tastes of weather (want cooler? Head north... Hotter? Head south...). If one is specifically looking for cool and foggy weather on the peninsula, Milbrae/San Bruno and points north are your best bets.

[NapaCab]

Thanks for the info, everyone. Sounds like we would have to go up as far as San Bruno / Millbrae to really escape the hot summers. Where I am temps average 85 in the summer months, often getting above 90 so even a slight change to 80 with more tree cover would help a lot. A bigger issue though is the lack of houses for sale around there. I hardly ever see houses coming on the market especially in Millbrae / Burlingame. Redwood City has a lot more inventory but the schools seem mixed in quality and as far as I know the climate there is the same as South Bay. What's San Mateo like?

[HockeyMac18]

Originally Posted by NapaCab

Thanks for the info, everyone. Sounds like we would have to go up as far as San Bruno / Millbrae to really escape the hot summers. Where I am temps average 85 in the summer months, often getting above 90 so even a slight change to 80 with more tree cover would help a lot. A bigger issue though is the lack of houses for sale around there. I hardly ever see houses coming on the market especially in Millbrae / Burlingame. Redwood City has a lot more inventory but the schools seem mixed in quality and as far as I know the climate there is the same as South Bay. What's San Mateo like?

I don't think you have to go that far north to escape the hot south bay-like summers. My point about going north of Milbrae is if you really want that cool weather (high 50's-60's) that you get along the coast in SF/Daly City, you'd want to go that far north to find it.

But if all you're hoping to do is get away from the typical south bay weather, things start to get cooler fast once you're north of Redwood City. When I used to work in Palo Alto, I used to enjoy watching the thermostat on my car drop as I drove north (when I drove) from work to home in San Mateo (and SF where I lived for a bit)...it could be as much as 10-15 degrees different (depending on the day) between PA and SM. And I play hockey in San Jose at least once a week, so I know how much warmer it can be down there compared to SM.


San Mateo is generally in the low 70's (high 60's aren't uncommon) in the summer - sometimes it'll creep into the 80's, but it won't stay there for long (at most a few days). I think I can count on one or two hands the number of times it's been in the 90's since I've lived here (>5 years). I don't have AC - my window fan does a great job of cooling my apt in the summer.

It also cools down fairly substantially in the evening when the cool breeze (rushing down through the San Bruno gap) spreads over the area. The San Mateo coast (between Coyote point and the SM bridge) is a very popular area to kite/wind surf because of this very consistent breeze in the afternoon/evening during the spring and summer - it's also a great place to bike/run/walk.

You can see climate info here: http://www.city-data.com/city/San-Ma...a.html#climate

I'd say weather in San Mateo (and surrounding mid-peninsula towns) is fairly ideal for what most people like. You seem to really prefer cooler weather (like me), but I think you'd still like SM weather.

[jade408]

San Mateo and Oakland have quite similar weather. Sunny in the summer, but rarely too hot.

[HockeyMac18]

Originally Posted by jade408

San Mateo and Oakland have quite similar weather. Sunny in the summer, but rarely too hot.

Agreed, Oakland and San Mateo I think have some of the best weather in the Bay Area.

[NapaCab]

Thanks, HockeyMac. San Mateo sounds like it might be right up my street, climate-wise. I can deal with some heat, up to about 80F, and if the nights are cool then that is a big plus. I noticed from a table of average weather too that the summer seems shorter there. What bugs me about where I am right now is that the hot temperatures start around April and it is still hot in October, sometimes even into November. That is just too much summer for me.

What are the San Mateo schools like? Any areas to avoid? Most seem pretty highly rated from San Carlos through to Burlingame. We are at the elementary school stage.

I had no idea Oakland had a cool microclimate either. Most of the East Bay is such a furnace in the summer so that is surprising. Oakland wouldn't work for us from a commuting point of view but still good to know...

[bentobox34]

Originally Posted by NapaCab

I had no idea Oakland had a cool microclimate either. Most of the East Bay is such a furnace in the summer so that is surprising.

You must be thinking of areas east of the Caldecott tunnel along I-680 or maybe the southern reaches of the East Bay (Fremont/Union City). Oakland/Alameda and all of the cities along I-80 (Berkeley, Albany, El Cerrito, etc.) get a heavy dose of cool air blowing in through the Golden Gate on a daily basis. This effect is especially noticeable in locations north of the Bay Bridge.