It will be windy and cold in San Francisco, quite cool during the day, if you are in the city itself. Inland (Napa) can be warm during the day, but it cools off at night all over California. If you are going to visit wineries, it will be chilly in the wine making and storage areas, and you will want a jacket. If you chill easily, something warmer than a windbreaker might be best. But it will be warm out in the sun. We layer lots here so we can put on and peel off layers as we need. June gloom is something we find we deal with here in California. Days are frequently overcast and grey.

One word of advice,,,, layer.

I have to admit that packing for this trip is more complicated than I thought. I always think of CA as hot & sunny and one thing I didn't realize was that the days can be so warm but the nights quite chilly in wine country. Our June nights rarely drop below mid 70's.

Hot & sunny is southern CA. Northern CA can be chilly one day and warm the next. Always plan on cool evenings in northern CA. I lived in the Sonoma wine country for 30 years before moving to Iowa.

I live 45 minutes south of SF and the weather difference in the summer can be night and day! Generally with the marine layer over SF, it's downright cold. Then on the same day you can drive inland or south, and it's in the 80's or even 90's. Crazy microclimates. I would check weather.com or similar for each area you plan to visit. You will freeze in SF if it's a typical summer day with only a windbreaker. Napa can be very hot during the day--layers, it is. Pants and shorts both. Have fun!

san fran is always cooler just because of the ocean location....as the others mentioned, layering light weight sweaters can help and not be as bulky as a coat or jacket...besdes you don't want to drag a coat while sight seeing...what helps is to throw in a pair of heavier socks...to me, warm feet are a must...

It matters WHERE in Sonoma County you are.
It can be 50 degrees on the beaches of Bodega Bay and 80 degrees in Windsor.

As the others have said... layers!

Thanks so much everyone. I live near the ocean (coastal NC). Our summers are very hot and humid. From May through usually late Oct. even cold-natured me doesn't need a jacket, though I keep a shawl or sweater handy for cold buildings. I've been watching the temps on my weather underground app. This is almost like packing for two trips!

When I first went to Sonoma County, I was so psyched for my CA adventure... warm temps, warm water, fun in the sun.

The day I arrived, the natives were walking their dogs, with coats, hats and gloves on.
The ocean was so cold that no one went in unless they had a full wet suit.
There WAS plenty of sun, but it was not warm.
I was totally unprepared for that!

Much of the coast from about Monterey north (includes SF) has pretty foggy/cool early summers. Later summertime and falls are fantastic, as is the weather when you go just a bit inland (as little as a few miles) or at places where there's a hill for separation from the coast.

Inland regions (including the wine regions) are predictably 90-100 in the summer but are dry with no humidity.

The cold water ocean is why we have such gentle weather - low humidity and no rain in spring and summer.

lindakathy is on point! Layer. Those who live there (I did), wear layers and take them off/put them on, in succession all day long.

Humorously!-you start with the bathing suit layer, followed by regular clothes, topped with an light jacket, or as we called it, a wind breaker. You take off the windbreaker, then the regular clothes and then when your'e done playing in the sun, as it gets later in the day, you add back the regular layer, then the windbreaker-reversing the order used earlier in the day.

I feel lucky. When we were in San Fran May 1 we had a week of sunny and 80 with little wind. Yosemite was the same. Loved it. Have a great time.

Layer,layer,layer. Be sure to bring something waterproof in case you get rain, it can go on top!

Rain is very unlikely, but the fog can be wet.

Remember that things are REALLY casual out here, and most people wear jeans, t-shirts and sweatshirts everywhere except in the fanciest restaurants. Dresses? I haven't seen women wear dresses for ages. Even the older women wear slacks.

If you take a ferry ride or visit Alcatraz, it'll be really cold. The weather's been cold cold all weekend--- we're down in Monterey.

Leave room in your suitcase so you can buy a couple of sweatshirts!

We have company from far away, so we went into Monterey for some sight-seeing and lunch. Saw exactly one person wearing a dress --- a six year old girl wearing a tutu!

Does anyone wear dresses anymore?

Not for sightseeing, that's for sure!

I basically live in maxi dresses all summer (except for work). I'm not a big fan of shorts: it's difficult to find any that fit me right. Same with jeans. I find the maxi dresses very comfortable and cooler than slacks. A lot of ladies wear them here and I see them on the lot of clothing websites/catalogs, so I guess they're popular somewhere. And yes, I wear them for sightseeing with sandals.

This post was edited by kittiemom on Mon, Jun 10, 13 at 23:07

My cousin says that those are popular in Hawaii, too. But the Northern CA climate has too many ups and downs during a day, or a week. On the coast, only tourists wear shorts. But I still don't see even the long dresses very often.

Layers, that's the code we live by!

Where are you located?

I'm in Wilmington, NC. Our summers are very hot and very humid. Temps during July-Aug are generally 90-100 and the humidity very high. Unless you are right on the beach, there isn't usually a lot of breeze. Our summer temps don't vary a lot. They're either hot or hotter. Our evenings and nights are very warm during the summer too.

I'm sure our climate is one reason the dresses are popular here. They're loose and there's some air flow instead of them just sticking to you in the high humidity.

Oh, yeah, our weather is very different! You'll have a great time on your visit and let us know all about it when you get home.

I totally wear dresses, even when sightseeing. There are comfortable outfits in every shape and style. Even when I lived in Monterey and Oahu. I just wore shorts under them when I was kid and climbing monkey bars. They are a thousand times cooler than contricting shorts.

I just stopped for gas this morning and saw a woman in a long dress getting gas. I said hi, and it turned out that she's a tourist just driving thru. And she was freezing this morning!

She just needed leggings for the underlayer. Ha!

How was the trip? Anything you would recommend to someone else?

The trip was great! DH& I hadn't been on a week-long vacation in 10 years. It was indeed very cool in SF. I was prepared with plenty of warm clothes but was still surprised at how cool it was. I think I took off my coat once. We didn't get as much sight-seeing done on the trip as I'd hoped. DH is a more relaxed vacationer than me. I like to get up early & see as many sights as as possible; he prefers a more laid-back schedule. We enjoyed Chinatown and Pier 39, but I'm sure most everyone who goes to SF goes to both of those. The Golden Gate Fortune Cookie Factory was quite interesting. We like jazz, so we very much enjoyed Les Joulins Jazz Bistro.

After leaving SF, we stayed at the Gaige House in Glen Ellen. We were in one of their Zen Suites, which was just beautiful. We would definitely stay there again.

The Sonoma Wine Trolley was very nice (they have one in Napa too). We went to four wineries and had a lovely catered lunch on the grounds of Buena Vista Winery. Each winery gave us a short tour and tasting. I highly recommend the blending class at Ravenswood. They teach you about what different wines do to a blend and then you get to make your own and they bottle it for you. If you're a Peanuts fan, the Charles M. Schultz Museum is nice. The Petrified Forest was quite interesting as well.

This post was edited by kittiemom on Thu, Jul 4, 13 at 14:38

sigh...made me miss ca again! glad you had such a good time in the city by the bay and wine country! maybe you can go again someday...