Wear a wet kitchen towel as a neck scarf

Heat rises, plain and simple!

If you're upright, heat escapes your body through your head, neck and shoulders.

The body's cooling system creates perspiration to cool you down. Moisture!
  Moisture helps dissipate heat.

Add Water

Wet your head and help heat dissipation. It doesn't have to be cold or ice water.

Your scalp doesn't need a brainfreeze. Room temperature seems to work best for me.

Rubbing alcohol diluted in water has a great temporary cooling effect on your skin.

At home I soak the shirt and shorts I'm wearing, the dampness has a cooling effect, especially if you stand in front of a fan.

Out in public, wear a wet bar or kitchen towel as a neck scarf.  Might look silly, but it serves a purpose!!

UV is sky high at the moment, protect yourself