Why don't plants get hot under sunlight?
Take a look at the Temperature paragraph from this reference:
Ecophysiology 


  Plants can avoid overheating by minimising the amount of sunlight absorbed and by enhancing the cooling effects of wind and transpiration.


They seem to have several ways to counter the heat as we do with transpiration, wind etc.

This article is more complicated but as really useful informations on the effects of wind on the plant's temperature:

Leaves in the lowest and highest winds: temperature, force and shape