Sacramento like most of California is mostly casual but unlike some of the other tips for this area I don't think running around in shorts and flip-flops in the summer is all you want to do. If you are visiting Old Sacramento or some of the other outdoor venues then its fine but in many restuarants away from the "tourist" areas a little nicer attire is appreciated. It's always HOT during summer but almost always cools off at night due to our "Delta Breeze" so bring a light jacket for the evenings, especially if you'll be close to one of our two rivers. Restaurants and shops are always air conditioned. We do get a touch of humidity but nothing extreme.
Camping/Beach/Outdoor Gear: There are many campgrounds within an hour or so drive but nothing close by unless you count a few KOA campgrounds along the freeway. If you go to the mountains for camping always pack some very warm clothes because even in the dead of summer it gets very cold. Remember it's the Sierras and the altitude can reach 7,000 ft.
If you come to Sacramento between May through October pack LIGHT!!! You wont want to wear anything becasue it will be about 110 degrees F with a bit of humidity coming off the river. A tank top (T-shirt for guys), cargo shorts and a pair of flip flops and you will blend seamlessly with the locals. This attire will be welcome at just about any restaurannt and bar as well.
For the winter pack the opposite, although still just as casual. Jeans and a cozy sweater will suit you just fine a coat wouldn't be a bad idea if you have room in your bags. It can be in the high 30's F during the winter.
Luggage and bags: Sacramento is extremely casual. It's very hot in the summer but the temperature does cool down in the evenings which makes it an ideal place to eat outside. This is not a city where people dress up. You can go to some of the best restaurants in Sacramento and even wear jeans if you like. The atmosphere is very relaxed and unpretentious. So, bring your shorts, tank tops, bathing suits, sunscreen and a hat !!
Camping/Beach/Outdoor Gear: make sure to bring warm clothes for at night. It's in the mountains, which cools way down in the evening. Just bring everything you would normally bring while camping.