Predictions are shown in Mountain Time.
Eruptions cannot be predicted with absolute certainty and estimates are derived from user reports.
GeyserPrediction
CastleNPS 06:45 ± 1 hour
GrandGeyserTimes 07:17 ± 105 minutes
CastleGeyserTimes 22:33 ± 1 hour

Predictions courtesy of:

GeyserTimes GeyserTimes
NPS National Park Service

(*) Prediction derived from double interval