The Best place to check for the current   weather situation in Taiwan before coming over for a trip is:

Central Weather Bureau 

Summer

Summer months are generally very subtropical hot and humid (especially July and August) throughout day and night.

However, many fruits will be in season and at the peak of deliciousness, like lychees.

Snacks like crushed ice "bao bing" (泡冰) will be common and refreshing.