When the mercury is rising, it should be an easy decision: Do you run the air conditioning or open the windows?

In reality, the choice isn’t always so obvious. You may think open windows are the more economical choice, but constantly starting and stopping your central AC or window unit can be inefficient and costly. And if you have environmental allergies, do you really need to run the AC even on mild days?

To help you decide, we talked to heating, ventilating, and air-conditioning experts about the best cooling solutions for any warm-weather situation.

The situation: It’s not just hot out—it’s also humid as heck

Solution: Run the AC

Climate makes all the difference when deciding whether open windows or air conditioning will be the most cost-efficient option. If you live in a climate that’s both balmy and sticky, the air conditioning will be your saving grace.

“If the humidity level is high, then anyone inside the home will feel uncomfortable,” says Rex Anderson, director of communications at Goodman Manufacturing.