about a year and half ago, I had a security light installed on my
garage with a day/night sensor. Latley, I have been noticing the light
flickers.. not a quick flicker, but inconsistent alternating levels of
light amount coming from the bulb (mercury vapor bulb).. it is kind of
annoying.. It has been working great up until recently.

Before I wonder if the power wire to the garage should be replaced, or
I start replacing fuses.. is this a sign the bulb is just going bad?
it is wet and cold right now.. a normal variance? I never noticed this
before..