It gets pretty warm around here and I usually wear a mesh jacket. I've currently got a Joe Rocket that works well and summer weight armored gloves.
I'll combine them with Icon Armor when I commute to work and Under Armour T's or Polo's with Icon or Slider Kevlar jeans on the weekend.
The Under Armour shirts breath really well and dry any sweat quickly.
2005 BMW F650gs Dakar
2004 BMW R1100s
2003 Suzuki SV1000n sold
2003 BMW F650CS sold
1981 Yamaha QT50 "Yamahopper" Joy of my youth
1976 Honda CB360T Rebuilt and gifted to Dad