Sleepyhead, that's exactly what I was thinking. As the weather conditions and forecasts are so dire practically everywhere now, someone organising the viva must have anticipated that maybe not everyone would be able to get in tomorrow. A good research administrator should have checked with the examiners about travel arrangements, given the circumstances.
Aloha, can you contact your supervisor tonight to confirm what's going on, just in case? It is an unusual situation, after all.