An improved LCD backlighting unit (“BLU”), preferably having white light emitting diode (“LED”) light sources, enhances a liquid crystal display's (“LCD's”) readability in sunlight. The improved BLU briefly increases a display screen's brightness, typically 2-6× greater than the BLU's maximum continuous operating brightness. The BLU brightness substantially increases brightness for a predefined and relatively short interval, typically 2 to 60 seconds, without damage. The LED driver control prevents boosting the display brightness too frequently or for too long thereby avoiding damaging the LEDs by adequately dissipating increased heat. The BLU may include a thermal sensor on or near the LEDs to provide real time temperature feedback to the LED driver control. The BLU preferably includes a thermal ballast that absorbs excess heat generated by the LEDs during intervals of increased brightness.