Overnight parking in California is a patchwork of local municipal laws rather than a single state rule. In many residential cities like Maywood or Menlo Park, it is strictly unlawful to park on any public street between 2:00 AM and 6:00 AM without a valid overnight parking permit; violators are routinely cited or towed. In larger cities like Los Angeles or San Francisco, overnight parking is generally allowed on streets unless there is a specific sign prohibiting it for "Street Sweeping" or if it is a "Tow-Away Zone." For those traveling in RVs or vans, "boondocking" (sleeping in a vehicle on a street) is increasingly restricted and can result in significant fines. However, California law generally allows you to stay in designated rest areas for up to 8 hours to prevent driver fatigue. If you are staying at a hotel, always verify if their lot is "open" or "secured" overnight, and in beach towns, be especially vigilant about "No Parking 12 AM - 5 AM" signs, which are strictly enforced to prevent overnight camping on the coast.