Why does my front derailleur not work when it is cold? When it is warm outside my front derailleur works just fine. But when it gets colder (40F) the lever on the handle bar does not catch and I can move it without any resistance the whole way without the derailleur shifting.

Update: The wire is not moving and the shifter is a Shimano Deore.

Any idea what can cause that and how to fix it?
I had bike with RX100 components where the grease in the brifters dried up and they would not catch as you have described. Its possible the grease in yous is soft enough at warmer temperatures for them to work, but once it cools down, it thickens.  There is an earlier post here on how to address it.