Temperature plays an important role in winemaking and there are several instances where a winemaking thermometer is an indispensable tool:
Yeast hydration is optimal at 104 F, and a 12" lab thermometer is a great, low cost tool for making sure you can accurately hit the targeted temperature and get your fermentation off to a great start.
Monitoring wine fermentation temperatures is important so you can avoid heat spikes or cold snaps which could adversely affect your yeast. A floating thermometer is really convenient because it can be placed and left in the must without fear of it sinking to the bottom of the fermenter!
Storage vessels can easily be outfitted with a winemaking thermometer to monitor their temperatures. These thermometers come in two forms: a Bi-Metal dial thermometer with a 6" probe" or a thermometer with a 2" probe" that screws into a 1/2" threaded female coupler on the tank, or as an LCD strip called a Fermometer that adheres to the side of the tank or bucket .