Getting wet or cold is the main risk. If you are in a temperate part of the world with little rainfall (check that forecast first) you will be fine. Even if you live somewhere where it rains a lot, or there is a risk of dew, provided you have a decent bivvy bag, or a water resistant sleeping bag, you should be grand.

The legality of sleeping outside depends entirely on local ordinances and the specific location. In many urban areas across the U.S. and Europe, "public lodging" or "street camping" is restricted by city bylaws to maintain public order and safety. In 2024, the U.S. Supreme Court (City of Grants Pass v. Johnson) ruled that cities can enforce bans on sleeping outdoors even if shelter space is unavailable. However, some regions allow "dispersed camping" on Bureau of Land Management (BLM) or National Forest lands for free. Sleeping in a vehicle is also subject to local "no overnight parking" signs. If you are caught sleeping in a prohibited public space, you may face fines ranging from $50 to $500 or be asked to move along by law enforcement. It is always safer and more legal to seek out designated rest areas, campgrounds, or "Boondocking" locations where overnight stays are explicitly permitted.