After another day of 90 degree weather across Michiana (that makes 18 days in South Bend this year), you've probably had the air conditioning running to beat the heat.
Whether you leave the A/C on all the time or you hold out until the sweat becomes unbearable, you can measure the energy used by the air conditioner through "cooling degree days."
As the National Weather Service explains, "degree days are based on the assumption that when the outside temperature is 65 degrees, we don't need heating or cooling to be comfortable." So, if the daily average temperature is above 65 degrees, you might need air conditioning to stay cool. The odds of A/C use go up the higher the CDD is.
So, why does this matter? The most common use of CDD is to track energy use. And, with warming temperatures due to climate change, the national trend has been that A/C and energy use have increased.