For shorter term, during otherwise decent weather conditions, and have a boat – suitable-size cabin cruiser and up – such could be a shorter-term alternative if primary house gets into (e.g.) utilities outages.

CriteriaESSCABs      Boats     Comment
Heat-Vent-Air Cond (HVAC)Yes!Some typesOptional on cabin cruisers and up, think 25 ft+, $100k+
Tornados, HurricanesYes!Heck NoSure don’t want to be on water when risk of very strong winds.
FloodingYes!Well…Sure could but be aware of all debris that often goes along with floodings.
Guest / Spare House, OfficeYes!No… not reallyThink of elderly, people using walkers, width of doors, steps, …
SaunaYes!NoNot on ‘Boats’, think Yacht, millions of US$.