I don't know if its just me but I swear the steering today I feel is heavier and requires much more effort on my part.
I was driving in normal mode. I've had the Nx for just over a month now and has always been a joy to drive. Has anyone else experienced this ?

Since I've had the car its always been warm and sunny, today is the first chilly day if that makes any difference.

 

Check your tire pressure if it's lower/deflated.

Hopefully other members who have this problem will chime in, otherwise I haven't heard of this problem.

 

Hahaha, I just happened to be in San Jose on the day you posted (September 9), and the temperature at noon was 76 degrees, but it didn't go over 86 that day after an overnight low of 65......must be tough to be a Californian on those cool late summer mornings.

I've yet to notice a difference in my F-Sport steering regardless of the temps and road conditions....I too would suggest checking the tire inflation, and if that's not the problem and the unusual steering persists....see your dealer!