The word "hibernal" refers to something related to winter or being wintry, so antonyms for "more hibernal" would be words that connote warmth, springtime, or summertime. Examples of antonyms for "more hibernal" include tropical, balmy, mild, temperate, warm, and hot. These words describe climates, temperatures, and even moods that are the opposite of those associated with winter. While "hibernal" evokes chilly, icy images, its antonyms paint pictures of beaches, sun, and relaxation. Therefore, if you want to express the exact opposite of something that is "more hibernal," you should use antonyms that describe things that are the complete opposite of winter.