I found this chart[1] and I do wonder how Oregon and Washington have such a high unsheltered population; I'm not familiar with the PNW, are parts of the states mild? The rest of that chart is pretty much in line with how I perceive winters to be.
The PNW has interesting geography: the Cascades run North/South right near the Western shore, and they catch most of the rain that the Pacific hurls at the area.
West of the mountains, it's temperate and damp. The Olympic peninsula is technically a rainforest, but the populous areas tend to get a lot of drizzle rather than heavy rain. Snow is rare at low elevations, even in winter.
East of the mountains, it's temperate and arid. Lots of power generation and agriculture on former tribal lands.
In the mountains, large national forests which allow dispersed camping.
It's not always "mild", but wherever you end up, it's usually not inhospitable. The summers have gotten much worse lately though, Seattle was a city where nobody felt the need for air conditioners as recently as 10-20 years ago. Now they sell out in the first heat wave of the summers, and new apartment buildings are starting to include them.
I'm not first-hand familiar with Oregon, but some parts of Washington have moderate temps. Coastal Washington gets a lot of rain but rarely freezes and -- anecdotally -- at least one city in Coastal Washington has vastly worse rates of homelessness on a per capita basis than some of the cities infamous for it, like Seattle and SF. And, yes, they are mostly camped outside, not in shelters.
Which city? I was in Spokane recently (obviously not the coastal city you are speaking about) and was surprised by how full of homeless people downtown was.
West coast winters are very mild, and there is very little humidity. We had a few days that got below freezing last year, most days were over 40.
If you need to live in a tent, or a broken RV with no AC or heat, would you rather live in Chicago (super cold), Houston (super hot and humid) or Sacrament to Portland (super mild year round, low humidity)
The coastal Pacific Northwest where most people live has mild weather all year, better than many parts of California. It rarely freezes in winter and rarely gets hot enough that you need an air conditioner in summer. Contrary to reputation, it has relatively few days of meaningful precipitation, especially in cities like Seattle that sit in a rain shadow.
If you are going to live unsheltered in the US, the cities in the PNW are definitely among the better locales to do so in terms of amenable weather.
Portland OR - cold and wet winters (occasionally the temps drop low enough that the rain becomes snow and/or ice). Hot and dry summers. Very dry summers. Not a lick of rain. Spring and Fall are a mix between the two. Gradually the rains taper off in the spring. Gradually the rains pick up in the fall.
West of the Cascades, it's mild. To the east of them the climate is decidedly less mild, though, so I'd be interested to see how the numbers would compare between the two regions.
1: https://www.thecentersquare.com/florida/article_67aeebc1-e7b...