Good sleeping weather

My dad used to say it on nights like we’ve been having the past few weeks.

“Good sleeping weather.”

Back in the day, there was no air conditioning at the young Huttner Weather Lab when I was a kid. The huge, old-school window fan roared to life every evening, sucking the hot air from the upstairs out the window and pulling cooler nighttime air in the other windows from outside. Of course, there was always the debate on which method was more effective, fan blowing in or out?

On hot nights we used to sleep in the hallway by the fan, so we sometimes liked to have it blowing on us. Ultimately I think dad was right, it cooled the house better to have the fan blowing out.

I remember the stories my parents used to tell about how people slept out by the lakes in Minneapolis during the heat waves of the 1930’s dust bowl summers. Apparently hundreds of people brought blankets and pillows out to lakes like Calhoun, Harriet and Nokomis and slept outside on hot nights before AC was widespread. I can picture the scene of families sleeping by the lake, and how unusual that would seem today.

The past few weeks have been ideal for home comfort in most of Minnesota. In the Twin Cities you probably have not needed air conditioning since June 25th, our last 90 degree day. Hopefully you have not had to run the furnace since that unseasonable and unreasonable cool spell that ended June 8th with a high of 57 degrees.

We keep track of home heating and cooling needs in weather through degree days. Basically it works like this. If you assume the average home is comfortable at 65 degrees, then anything warmer or cooler requires additional energy to maintain home comfort. If the day’s average temperature was 80 degrees, then it requires 15 degrees of cooling to keep your home comfortable. That would be 15 cooling degree days.

This month the Twin Cities has had no heating degree days. We’ve only racked up 31 cooling degree days. That’s pretty close to the base average daily temperature of 65 degrees. It’s also why you probably are saving money by not running the air conditioner.

The bottom line is it’s pretty comfy these days in Minnesota. If you manage your windows right through the day, nature keeps your home comfortable. The only thing you have to do is decide which way is better. Fan blowing in, or fan blowing out?


  • Father Knows Best. Fan exhuasting the air inside out was the way we did it. I remember the ceiling fans at the drug store keeping us cool as we drank our lime fizzies. Nice story about surviving the 30s.