Those strawberry blondes were my recommendations before they clarified the hair color was darker. Some of them are dark enough but some of them are way too light.
I don't think all brown hair can be completely ruled out. Brown hair can turn significantly redder in the sun. I think it needs to be a medium brown or a light brown to be potential match based on hair color changing due to sunlight. The people with the super super dark brown hair wouldn't be a match. And the very pale light strawberry blondes wouldn't either. Dark blondes and light/medium browns could match. It's very possible the missing person's family didn't mention red tones if their hair didn't normally show red when they weren't in the sunlight.
Alternately, all blonde hair colors can't be ruled out either. As a natural light blonde my entire life, I've always been amazed by the brown hair that is often classified as blonde hair. For example the following picture (below) is described as blonde hair on a hair color website. And that's NOT blonde IMO but people call it blonde, and even hair color companies call it blonde. So a dark blonde hair color defined as blonde or strawberry blond could be match, especially if there is no picture showing the hair color, because dark blonde and light brown are almost interchangeable hair colors.