On the United States Department of Agriculture plant hardiness zone map, Zone 1 is the coldest, zone 11 the warmest. Except for the high elevations, Keene has gone from zone 3 to zone 4.

According to the New York Times, the record heat of the summers of the last two years is not an anomaly but the continuation of a trend. The five hottest Julys have occurred in the last five years, and nine of the 10 hottest have occurred since 2005.

While I hate to sound like the old-timer I am, I’m here to tell you that it used to get downright chilly after dark in the Adirondacks. No longer. According, again, to the New York Times, nights are warming twice as fast as days.

Most people I know have gradually acceded to the use of air conditioning over the past few years, although some have resisted more stubbornly than others.

My sister is a professional gardener, and the stultifying heat was killing her. I ordered her a new air conditioner, but she still wasn’t using it until I let her know how mad that made me. What are you waiting for, Sissy? Armageddon? Maybe you want to see if you’ll self-combust. Since then she has bought AC for her studio as well.

My cousin Melinda moved into a new apartment in Ann Arbor, Michigan. There is an air conditioner in the bedroom, but, even though it was sweltering inside the apartment, Melinda refused to turn it on because “it was too early in the season.”

Melinda, a practical though stubborn person, has her own methods of temperature control. She opens her windows at night and closes windows and curtains in the daytime. She sets up two fans for cross-ventilation. The trick is, to cool the room, point one fan toward the open window, and place another near an open window on the opposite side of the room. Eventually Melinda broke down and started using her AC on and off throughout the day in addition to the fans.

My sister, Melinda and I remembered that our Grandmother Allen used a powerful fan to blow air over a big basin of ice in her living room. We were constantly admonished to keep our fingers away from the spinning blades.

It turned out my sister used the same method I did for cooling her house. Early in the morning, before the heat of the day built up, we put a fan in the doorway to pull cool air into the kitchen from the out of doors.

“I do it every day,” my sister said, “but it never seems to work as well as I think it should.”

I began to study up on the subject. On howstuffworks.com, I learned that fans do not create a vacuum, and so do not suck air. It is therefore no use to try to bring in cool morning air the way my sister and I tried to do. All a fan can do is push air.

One site advocated placing slices of cucumber on the forehead and wet washrags on the back of the neck while eating minty treats and jalapeno dishes.

“If nothing else, the endorphins released by your body in response to the hot pepper will make you not care as much about the heat!” the author quipped brightly. Use of sombreros was not mentioned, but taking a siesta from 10 a.m. to 3 a.m. was suggested.

A fan does not actually cool the air in a room but, conversely, gradually heats the air by its rotation. It makes a person feel cooler by evaporating perspiration on his or her skin.

Why then does Jupiter the cat, who does not sweat, lie directly in front of the fan in hot weather? Does the breeze make him feel cooler, and if so, how?

I learned that the wind-chill factor can cause moving air to cool down even dry, inanimate objects, and I was asked to refer to radiation, conduction and convection, a subject I would gladly explain to you if I had more time. (Did I mention that you can place a cucumber slice on your forehead?)

Keep cool, and have a good week.