It's not the Humidity; It's the Heat.

My front door sticks and is tough to open in the summertime.  It definitely doesn't happen in the winter.  (I think it happens only above 70 degrees F.)  If the weather is rainy and cool, it doesn't stick.  If the weather is hot and dry, it does.  I can't just ask the handyman to plane the edge of the door.  I learned after trying to drive a screw into the door last year that it is a metal door, not a wooden one.  I'll just keep shoving the door to open it from the outside.  (It's a little tougher from the inside.  I feel as if I'm going to yank off the doorknob.)