Answers to this question are varied, but let’s cover the most common reasons your toilet may be sweating in the winter.
1) You have a water-saving aerator or low flow valve attached to your toilet tank. The extra strain of saving water can cause pipes to expand and create excess pressure that causes your toilet bowl to sweat excessively when it is running slowly. This will provide you with an explanation for why there are so many reports of toilets leaking in cold weather!
2) Although not always related, pipe leaks also could be causing sweating commodes since they cannot handle any additional build up during those slow days on vacation from work, school or being sick at home. In some cases where pipes have been damaged by freezing temperatures over time, they might even fail completely which will leave you no choice but to replace them as well as install a new hot water heater.