Why is it that whenever it's really cold out, our lightbulbs outside go out?

Answer 1

I'm guessing that your outside lights are either white fluorescent tubes or yellow sodium vapour tubes. Both depend on passing an electric current through a glass bulb containing a very low-pressure gas; mercury vapour or sodium vapour. In very cold weather the pressure of the vapour is lower. If it drops low enough, the vapour won't conduct electricity and the bulb won't light.

Answer 2

*Probably* because the the heat that build up so quickly from turning on the lights is too much against the cold start-up and the filament breaks.

It's not unlike taking a hot glass and tossing it in ice water......I am guessing that you can imagine what happens here (crack crack crack crack crack crack!).

:)

Answer 3

where do you live