I used arm and leg sleeves when I lived and rode in the desert west of DFW. Sunscreen on all other exposed skin required re-application on all-day rides. It was frequently over 100F, with blazing sun from sunrise to sunset. Squiring a bit of water on them feels amazingly cool.

Granted this was extreme dry heat; a humid climate may be different.

Nonetheless, they get a big thumbs up from me.