My friends and I used to hike that general area all of the time, mostly around The Ape Caves, in the early 70s. Around Ape Caves altitude could start to be a problem, but leaving from Willard is not much above sea level. However, you climb fast there which can mean exhaustion with all of your calories burned up and no reserves. The rules are the same as for hiking the Grand Canyon, a man's gotta know his limitations.
"There's a book that covers EVERY known death in the Grand Canyon. It's a fast read and fascinating, with the majority of people just not understanding that the bottom is WAY hotter than the top, and they die from dehydration."
Read the book again, the number one cause of death in the Grand Canyon is air crashes. Also, very few have died from dehydration, it is heat exhaustion and heat stroke that get most of the hiker deaths. I have hiked down and back many times, including in June and July at 110 degrees.
Whether you are hiking in Skamania County, the Grand Canyon or many other places, preparation and knowledge are key. Remember, junk food is health food and health food is junk food on that day.