climactic
Pronunciation: /klʌɪˈmaktɪk/
adjective

Origin:
late 19th century: formed irregularly from climax + -ic, probably influenced by climacteric

Climactic and climatic are very similar in spelling and are often confused. Climactic means ‘forming a climax’, as in the film’s climactic scene, while climatic means ‘relating to climate’, as in prevailing climatic conditions.

Do not confuse climactic with climatic. Climactic means 'forming a climax' ( the film’s climactic scene), whereas climatic means 'relating to climate' ( global climatic changes).