Clothing/Shoes/Weather Gear: I cannot stress this enough: layer. It's true that San Francisco can be very cold and foggy, and fog often makes way to light rain, so rain jackets are a must 9 months out of the year. However, if you plan on doing a fair amount of walking, you're going to get warm pretty fast, as the hills can be brutal. Good walking shoes with traction are great for the steep downward slopes on the other side of those hills.
Luggage and bags:
Backpacks are excellent for putting your camera as well as some of the souvenirs you buy along your visits to the shops.
Clothing/Shoes/Weather Gear: Make sure you bring a beanie, scarf, sweatshirt, sweater and a nice warm jacket. The weather can be very cold around the pier.
Clothing/Shoes/Weather Gear: San Francisco is a place of fairly mild weather all year long during the daylight hours. However, by night the weather can change very rapidly, the fog rolls in from the bay, and the city can experience some pretty chilly nights. Pack warm comfortable shoes, dress in layers, carry a sweater or two and maybe a well lined jacket. Come to San Francisco but dress for WARMTH!
Luggage and bags:
Backpack it all the way! Towing luggage around the hills of SF is no fun.
Clothing/Shoes/Weather Gear: If you are staying in the bay area, make sure to dress appropriately for your location. The weather can change dramatically within a 15 minute drive. The city (SF) is always much cooler than anywhere else. If you stay in Marin (like I did), you will want flip-flops, shorts, and a t-shirt for summer visits. But a 15 minute drive into the city can change your wardrobe drastically so be sure to layer!
Camping/Beach/Outdoor Gear: Bring outdoor walking shoes. There are tons of great trails around the bay area. They are a must do if you enjoy walking along the green hills and California coast.
Always dress in layers. It can be really warm at noon, and it gets chilly a few hours later. Summer in SF is generally chilly, so be prepared to be able to take out and add layers of clothes throughout the day.
Camping/Beach/Outdoor Gear: Don't bother with bikinis :). In as much as we have beaches all along the coast, the water is always cold.
Just remember that SF always gets cool during the evening hours. Even if it is warm and mild during the day make sure you always carry a light sweater or jacket with you if you are going to spend the entire day on the go.
You're going to do alot of walking so bring your comfy shoes.
Photo Equipment: Always bring your camera. There are photo opps everywhere.
Luggage and bags:
Your usual roller board and duffel bags.
Clothing/Shoes/Weather Gear: Casual wear and good walking shoes and socks. Sweaters, gloves/mittens, scarfs and an umbrella during the Oct-April months.
Toiletries and Medical Supplies: Your medications and vitamins. Should you forget them, local pharmacies are easy to accommodate your prescription orders and can get them to you on the same day.
Photo Equipment: Photo cameras of all type for taking pictures. Major brand stores operate in the city, Best buy and Circuit City. Check with Walgreen's for your photos "on the go" type cameras, disposable, digital and panoramic view. They also process your 35mm film usually within one day for a higher fee or several days if you're not in a time constraint.
Miscellaneous: Most of what you need can be bought in and around the city should you forget something.
Clothing/Shoes/Weather Gear: Layers, layers, layers. Even in the warmest months, San Francisco visitors should always bring a light jacket. Unexpected upswells from the deep and frosty Pacific Ocean and chilling blasts sweep over San Francisco without notice and can change San Francisco's weather in an instant. Overall, jeans, light sweaters, long sleeve shirts and close-toed shoes make up the typical San Franciscan's wardrobe, with the occasional voyeur daring a short skirt (pared with a heavy jacket) and sandals in the "summer" months.
Downtown, it can get sunny and warm. Sometimes along the coast (Ocean Beach, Pacifica, down Highway 1) it can get foggy and chilly. Usually, a windbreaker or a light jacket will suffice. Sandals are ok, but if you are interested in walking the streets of SF, maybe consider bringing a pair of comfy shoes (because of the hills, etc.)
The weather is so finicky in SF that you can be in the cold & fog of the avenues, and then hit Japan town a block later and be sunny and warm. Just be prepared.
Sonoma in Napa Valley is usually quite warm, so shorts and a t-shirt (or tank top) is sufficient. However, bring a windbreaker or a light jacket for the night, or if you want to go to SF downtown.
Luggage and bags:
Bring a daypack and put a sweater into it. This is also a GREEN place to put souvenirs bought, as San Francisco has now passed ordinances against the use of plastic bags in shopping. Also, as a convenience, have plenty of quarters to put into the MUNI transport ticket machines. The machines also accept bills, but won't provide any change, so you want to put in the exact fare when buying a ticket.
Clothing/Shoes/Weather Gear: Although the urban transport is very good, visiting San Francisco will mean a lot of walking, so bring good comfortable walking shoes that can pound the pavement all day long without giving you heal spurs or toe cramps. Even in the middle of summer, the marine layer can blow in and make this city surprisingly cool, particularly in the morning and evening hours, so always bring along a sweater to layer over the shirt you may be wearing. Winter weather is surprisingly forgiving though, as it very rarely freezes in San Francisco. Visitors from the Eastern USA and Northern Europe will find winter in San Francisco quite pleasurable overall. At the same time, the wind chill factor from the ocean and bay breezes can make the weather seem particularly cold, so bring a warm jacket in winter.
Photo Equipment: A good wide angle lense is nice for capturing architecture. In museums, flash is prohibited, but photography is OK, so have a camera that takes decent images even in low light conditions. Bring plenty of memory for your digital camera.
Miscellaneous: Generally, fog comes mostly in the late spring and early summer, while winter is more likely to be clear. The water that surrounds the San Francisco peninsula moderates the climate in dramatic fashion, making weather reports from the surrounding Bay Area and Northern California poor predictors of weather in San Francisco itself. In summer, San Francisco will be as much as 30 degrees cooler than Sacramento, while in winter, it will be 30 degrees warmer.
Clothing/Shoes/Weather Gear: In San Francisco, you should pack a sweater and a light windbreaker jacket. The climate is very mild, never getting very hot or cold. But the weather is constantly changing, and can vary even from one neighborhood to another. So always be prepared for rain or shine.
If you're visiting in the summer bring warm clothes. Sweater, Jacket, Scarf, Long Pants. It is foggy and cold in San Francisco in the summer, especially at night. Feel free to bring some warm weather clothes if you plan to visit the wine country or Sausalito or anywhere outside the city.
San Francisco tends to be warm in September-early November.
In the winter bring a rain jacket and umbrella. Although it's probably a good idea to have them in general. Not just winter.
People usually dress up for going out at night.
Toiletries and Medical Supplies: You can get pretty much anything you need at a Walgreens here.
Miscellaneous: A good MUNI guide is helpful. Some hotels will hand out a single page guide with bus routes so maybe you can call yours and ask otherwise try to order one if you'll be using the bus and cable cars to get around.
Clothing/Shoes/Weather Gear: One year, when I visited in early fall, I was ill prepared for the 98 degree heat wave. When I first visited in July, 1990, I was ill prepared for how cold summer in San Francisco could be. Lesson learned: bring a little bit of everything -- t-shirts, sweaters, sweatshirts, light jacket, etc. It's also a good idea to layer, as the temperature can change drastically from morning when the fog has yet to lift, to midday, usually the warmest part of the day, to late afternoon and evening, when the fog in many areas of the city rolls back in.
Luggage and bags:
Depending on where you are staying, there are many hills in San Francisco. Thus, for luggage, make sure you can adequately transport it without being tired from walking all over the hills to get to your hotel. Or, one can just take a cab or public transportation.
Clothing/Shoes/Weather Gear: Too many tourists come to San Francisco wearing and packing only T shirts and shorts. That is a big mistake, as San Francisco weather is on average, much colder than most cities in the summer. Whichever season you come to SF, make sure you bring a jacket and clothes for layering (T shirt, long sleeve over, a sweater when it's winter time, and a jacket). Also check the forecast for rain. The fall tends to be the best season weather-wise for San Francisco (especially mid-to-late October when we have an Indian Summer). As for shoes, wear comfortable shoes, as there are many, many hills.
Camping/Beach/Outdoor Gear: Unfortunately, almost all of the San Francisco beaches are too cold to sunbathe or swim in. Thus, only bring swim suits/trunks if you have access to a pool... This is true in the summer as well.
Clothing/Shoes/Weather Gear: We were in San Francisco in the fall, which is probably the best time to go. I found the weather varied from 80 degrees to 58, depending on the location, time of day, rain or fog. So bring stuff that can be layered. Oh, and an umbrella! If it's cold and foggy in the city, as soon as you cross the bridge to Marin County, it can be immediately hot and sunny.