Summer is a big season to fruit, to me to everywhere in Taiwan(ha) because there are so many sweet and juicy fruit in this season!
let me take some examples for you:

apple

papaya

watermelon

Juicy Peach(very sweet and juicy!)

mango

banana

litchi

Night-blooming Gereus,
Pitaya，Dragon Fruit.

with kiwifruit

I know,
there are some of them have no season issue in Taiwan, for all seasons you can buy them easily, they are just my family buy them often!!^^ XP

but honestly, I feel they taste better specially in summer ! ;P