Here's a graph of Happy Hanukkah Radio's signal strength during their 4 December 2013 transmission. The graph starts just before sign on, and runs until just after, so you can see what the background noise levels were like. They were about S4/S5 at sign on, and S3 at sign off.
HHR's signal was S8 at sign on, and it dropped to S5, at which time it was barely audible. It then quickly came back up, to roughly S9 with some peaks above that, and remained excellent until sign off.
One thing you can take from this is that even if you are not hearing a station others are reporting, it pays to continue to listen, as propagation can dramatically change in a matter of minutes.