3 or 4 years ago, dad and I went the first week of January. We saw -16*F as we drove through Green River. I don't think the temps got above 35*F the week that we were there.
Even around Bullfrog, we didn't see another boat. Interesting experience, but spooky. After that trip, I bought a kicker for my fishing boat as I didn't want to worry about breaking down on the lake. I figured even if I was up in GHB, I could get back home with a problem with my big engine (even if it would take 7 + hours).
Even when we found the fish, they did not want to cooperate. I know more about the lake now, and like to think we would do better. But it was a rough trip in regards to catching.