I too frequently hear people say “anticlimatic” when they mean something else.

Problem:
“Anticlimatic” is a nonsense word.

Explanation:
Except for that use by those who have turned “anticlimatic” into a word applicable to climate — although it’s difficult to imagine what it means to be “anticlimatic” — this is a nonsense word.

Nearly everyone who says “anticlimatic” actually is trying to say an adjective whose meaning is expressing or pertaining to anticlimax.

“Anticlimactic” (notice the ‘c’ before the ‘tic’) — not “anticlimatic” — is the adjectival form of the noun “anticlimax” (just as “climactic” is the adjectival form of the noun “climax”).

I believe that the use of “anticlimatic” is consistent with my “Devolution toward Simpler” linguistic hypothesis. It’s simpler to say “anticlimatic” than to say “anticlimactic” (which requires the speaker to emphasize the middle ‘c’).

For fun, I searched Google for each of the following words and got about the indicated numbers of matches:

• anticlimatic — 283,000 matches
• anticlimactic — 401,000 matches

Assuming that the co-opting of the nonsense word “anticlimatic” by climate writers is an insignificant portion of the “anticlimatic” count, this tells me that Web authors have written the word correctly vs. incorrectly by a ratio of 1.4:1, which is a bit pathetic.

Solution:
“Anticlimactic”