What does 夏蟬叫荔枝熟 mean?

I found this sentence online and it was presented as a saying about eating lychees in good weather? 夏蟬叫荔枝熟? The literal meaning is a summer cicada calls the lychee ripe? From what I read in Chinese from other people, they all wrote about how great lychees are in the summer (which I agree with haha）. But I don't understand the implied meaning from it. I really don't even want to try and guess.

Can anyone clarify the meaning please? Thank you 晒.