I don't know if there is some sort of crazy juice being passed out there, but Soda Springs, and that whole area, is definitely not arid. I'm not as familiar with the mileage distance to get there, but I do know that from Seattle, it took about 2 hours to get there, might be that or less from Renton.
It's DEFINITELY not arid though. When I went, the temperatures were, I think, in the 80's. But there was plenty of trees, mixed with the higher altitude, which made for a surprisingly cool day. And of course there are glacial river run-offs which are not too cold, but would definitely feel good to jump in.
That isn't to knock Bradbury's location at all, just to clarify that Soda Springs and the Wenatchee National Foreest area is far from arid. (Hence the "National Forest" moniker.)