Hello Sue, This weather station’s color display features three different lighting settings:
High (100%) brightness, Medium (60%) brightness and Low (30%) brightness. Using battery power alone, the backlight is available momentarily for 10 seconds by pressing the “Lightbulb” button. When display is powered with the power adapter, backlight remains on at 100% brightness. Press “Lightbulb” button once to dim to 60% brightness; press again to dim to 30%, press a 3rd time to enter “AUTO DIM” mode. Unfortunately, this model does not have the option to turn off the backlight. Please let us know if you have any other questions. Thank you.