I have never been to Lassen Volcanic Nat'l Park. I would like to do so sometime in the future, not this year.
Have any of you guys camped/visited there?
We have tented there many times. It is a great place. Good day hiking, lots of thermal activity and you can climb the volcano
. Lots of well done info and things to see and do. Also close to other volcano parks.
There are gas and groceries available in the park.
There are two camping spots we have used. One is in the saddle at 8,000 feet. It is very rustic, mostly tents, no hook ups, on a small lake, lots of wildlife, dome toilets. There was still snow on the ground in mid June. The other ,Manzanita, campground (South entrance, I think), lower elevation on a lake, has showers. I don't know about hook-ups but I have seen bulge mobiles here.
In May you might get snow. June through September should be no problem. It gets very cold at night in the upper elevations and can be in the 90,s during the day so layering is good thing.
It is really worth seeing, go for it!