I think it's funny that the volcanic fumaroles are listed. On one hand, yes, they're certainly active geothermal sites. On the other hand, the page is tailored to hot springs.
Average temp: 250F above ambient. Status: Open for soaking. Note: Please don't soak.
Well, the ones on the summits of Hood and Rainier are just so readily accessible that it'd be a shame not to dip your toesies in.