Yeah, it could be trouble. I almost got stuck in EWR on a Friday a couple of weeks ago. Had a 6am flight I had to miss for work and got to the airport at 11:30am. I was checking availability on expertflyer all morning and all coach fare buckets kept going to 0 before SDC window opened. I was on standby as I could not get a SDC. I almost made the 3:30pm flight (I was 5 on the standby list and they cleared 4) and then hell broke out. The CVG flight on a CRJ cancelled and everything oversold through EWR. At 4:30pm thunderstorms hit and closed the airport.. making it even worse. I called SMS after the thunderstorms and they coded my itin to interrupted travel which allowed them to send me out of PHL the next day (as all flights out of EWR were also oversold until Sat night, causing me to miss the last flight to my final destination).

Needless to say, I am much more apprehensive on SDC later in the day if the buckets are not wide open... thank god for SMS and weather...