Lights that use 10w chips seem to give off plenty of heat. Mine do, anyway.
The 10W CREE XM-L chips give off noticeable heat(from the front of the emitter, not the heatsink) a couple inches away. No PWM and driven at 100%
The covers I tinted blue actually got hot enough there is a slight circle shaped deformation in the optix(trade name for acrylic sheet) in front of each LED. I didn't have an issue at SnoBall, or last winter living in MN. It only took a couple minutes for built up snow/ice to melt off, with my lightbar mounted in the grill.