I tape the temp probe to the side of my fermentation bucket and cover it with a few layers of bubble wrap. It's the temp of the fermenting wort that matters, not the air temp per se. Because fermentation produces heat, the ambient temp inside my freezer is usually a few degrees below that of the fermenting wort for the first few days, then they equilibrate as active fermentation tapers off.
Primary/Secondary: #109 Rye, #110 APA
Kegged: #106 American Wheat, #107 IPA, #108 Nut Brown
Planned: Red IPA, American Brown