As someone who was homeless (for less than a year, thankfully!), my experience was that many people with nowhere to go (myself included) become incredibly despondent that they have no roof, no shower, no place to keep (let alone wash) their clothes and turn to drugs as a way of (temporarily) ameliorating their suffering.
Those with mental health issues often can't hold a job as they're suffering from debilitating mental illness (duh!) and those with no place to shower or keep clean clothes have a hard time getting, keeping jobs too.
The latter group mostly just needs the opportunity to present themselves for job inquiries bathed, reasonably well rested and in clean clothes.
The former group needs the same plus mental health services including supervision and treatment.
Don't forget that more than half of Americans are an unexpected $600 emergency away from being unable to pay for food, rent, utilities, etc.
But most folks ignore that and instead just want them gone. They don't care where -- in jail -- in another city -- just as long as they don't have to look at them. It's disgusting.
Really, the land of the free is going to enforce showering laws? If our standard for freedom is that low, I'd lock up all the people spreading fear - they do far more damage.
Meanwhile it's 70 deg F here in Atlanta. California and Florida have even warmer temps.