Temperature variance refers to the difference or change in temperature. It indicates how much the temperature varies or fluctuates over a given period or between different locations. Full definition
Increased temperature variance adds to the probability of extreme high temperature events over and above what could be expected simply from increases in the mean alone. (ipcc.ch)
Scientists call this a decrease in temperature variance, and it implies fewer temperature extremes, in this case notably fewer cold extremes. (theconversation.com)
There are three main ways to exploit energy from the ocean: from the tides, from waves and from the ocean's natural temperature variance as depth increases. (worldenergy.org)