Predictions are shown in Mountain Time.
Eruptions cannot be predicted with absolute certainty and estimates are derived from user reports.
GeyserPrediction
CastleGeyserTimes Nov 20 @ 23:01 ± 1 hour
GrandGeyserTimes Nov 20 @ 23:51 ± 105 minutes

Predictions courtesy of:

GeyserTimes GeyserTimes
NPS National Park Service

(*) Prediction derived from double interval