Dramatica theory states the entire story is a metaphor for the workings of a human mind. If you want to use something like ‘the weather’ as a character that tries to prevent the Goal from being reached, it works just fine. This is because the weather, just like a human character, is just another metaphor for the workings of a human mind. As such, the human in your story that is pursuing the safety of base camp is the same thing—well, a similar type of thing, at least—to the unrelenting blizzard that is stubbornly preventing the character from descending the thousand foot icy cliff. That is, they are both processes of the human mind at work solving a problem. They are just different processes.
Consider the following from Melanie Anne Phillips article Character Development Tricks!.
Suppose we wrote the sentence, "The rain danced on the sidewalk in celebration of being reunited with the earth."
Now we are definitely assigning human qualities to the rain. Without doubt, the rain has become a character. Characters do not have to be people; they can also be places or things. In fact, anything that can be imbued with motivation can be a character.
Your characters don’t themselves have to be sentient because they are already standing in for a sentient being (the human mind). They just need to be able to express the process they are meant to express to the audience. The weather needs to somehow be imbued with the motivation to prevent the Goal from being achieved.
I assume that severe weather that is not imbued with the motivation to prevent the Goal would just be considered an obstacle to reaching the goal. And that humans within the story that aren’t given motivations, like guests at a park who are only there to be eaten by dinosaurs or who only show up to be terrorized by the ghosts that have been set free in the middle of NYC, aren’t so much characters as they are props.