The word "more aestival" refers to something that is very summery or related to summer. The antonyms for this word can include "less sunny", "more wintry", "less warm", "more autumnal", "less tropical", "more chilly", "less balmy", and "more wintery". These words indicate a change in temperature, climate, and seasonal attributes. The opposite of more aestival may also include words such as "less vibrant", "more muted", "less colorful", and "more monotonous". When you want to describe something that is not so summery, you can use these antonyms to convey your message.