Whether you stay the day, the night or the weekend, you can return to the U.S. easily. Only non-U.S. residents must present passports and visas for entry. U.S. citizens need only proof of citizenship, such as a copy of your birth certificate to re-enter California and even that is rarely requested.
Seasons are clearly defined in Baja: winter is cold, spring and summer are sunny. Of course there are snow covered mountains during winter and very hot deserts in summer.
It is wise to pack a light jacket or sweater during summer and something really warm for winter.
In major cities some nightclubs and restaurants observe dress code, we recommend to call before going out. Usually at this places the rule is: no tennis shoes or sandals, no caps or hats, no shorts, no t-shirts, no jeans.
You can bring in your car, personal clothing, camera and other items for personal use. For food or medicines, there is a per-person limit of up to US$400 duty free. Anything over that amount has to go through Mexican customs and pay import duty. It’s a federal crime for anyone to bring into México: