I responded to a similar post last month.  I had an issue like this
and no one else could figure it out until I tried something new.  I
live in Georgia, the Dirty South, and it gets real hot down here.  I
had this issue for years and it got much worse last September.

My problem was that the ignition switch is plastic and the lock
cylinder is metallic.  The heat caused the cylinder to get really hot
and thus the plastic of the switch would expand and no matter how hard
I would turn the key, it would not turn the switch far enough for
ignition.

Even when the weather was not that hot, the car was hard to crank. I
had to turn the key extra hard and fast for it to crank. I even
developed callous on my thumb.

I didn't replace the switch, but I could have. Instead, I found
something to place between the switch and cylinder.  So, that even
when it gets real hot the cylinder will still turn the switch far
enough to crank the car every time.  Haven't had a problem since.

1996 Maxima GLE