Temperatures to expect on a Northbound CDT hike.

N/m

I did some Section Hiking on the CDT this (2014) Summer.
CC to Lordsburg, Silver City to Snow Lake in NM and South Pass
to Elkhart Park in WY and used a Zpacks wide Long. I also carried
a light down jacket w/ hood once I got north of Silver City.
I'm 5-11 and 200lbs.
It got pretty cold for the last 2 nights up the Gila r. canyon
below Snow Lake. Cold enough to freeze my shoes SOLID but not
cold enough to freeze my water bottle in the tent with me.
'The shoes were outside.
I wore the down on those two nights and was a little chilly at times
during one night but didn't have the zipper closed up. I'm pretty
sure it didn't get down to 20 but obviously did get below 32.
Oh, and I was inside my SolPlex with lots of ventilation.
I used an uninsulated GG Air Beam Sleeper and that may have made the
difference.
No problem at all up in the Winds in late July early Aug.

OldnSlow

In the San Juans if you are coming through in June it could get near freezing every night, but likely not below 20. Later June would probably be more stable. I've seen it snow / hail several times though around the 4th of July.