When warm, I'm able to get it in from a slight roll without double clutching. Now, even with double clutching I get denied.
I used a little more force than normal on one attempt today and was met with a nasty crunch sound.

 

You have syncros, and don't need to double clutch. It doesn't do you any good.
I've noticed a little more force being required to get into first gear, but I also installed a short shifter so attribute my added difficulty to the short shifter and not the weather.

 

about 10 degrees F here...so problems so far.

 

Have you changed your gearbox oil?

 

I only double clutch when going into first. Especially if I'm going faster than 5mph.

 

No, should I?
I have a 06 with 47k miles on it. Mostly highway so not too much shifting, but lots of stop and go, so it might be a wash.

 

I have had the issue with the high performance gear oil like Royal Purple, it would happen until the oil warmed up.

I am not sure if it may help or harm so not sure I would recommend changing to fix this problem.

 

i highly recommend changing your manual tranny fluid. i've changed mine twice now and each time it was black like motor oil, and the stuff is supposed to be clear. mind you i was still within the recommended period before it needed changing. my lesson is that the tranny fluid should be changed earlier than acura recommends.

i'm not saying it will fix your specific problem in cold weather. but i would do it either way. i did mine myself in my driveway.