I did it this morning from Falls Church to downtown DC. It's basically clear with a few surprises. If you do it the first time during the day, probably would not be much of a problem at night with a good light. I went a bit slower and tried to be very aware of any ice. I only had to dismount twice near the Memorial Bridge, on both of the bridge there are places where runoff from the GW Parkway flows on the trail and freezes and forms some ice patches which cover the entire trail for a few yards. .Another area to watch out for is from the S Curve of Death, across the bridge over Spout Run and along that newly paved stretch, there is lots of ice there too but I never had to dismount, just take it slow in a few spots.