Concerned with intense experience regarding long-term weather keeping cold (9)
I believe the answer is:
climactic
'cold' is the definition.
Both the answer and definition are adjectives. Perhaps you can see a link between them that I don't see?
I cannot understand how the rest of the clue works.
Can you help me to learn more?
(Other definitions for climactic that I've seen before include "Coming to a high point" , "Coming to an exciting finish" , "Coming to exciting peak" , "Rising to a peak" , "Decisive" .)