Predictions are shown in Mountain Time.
Eruptions cannot be predicted with absolute certainty and estimates are derived from user reports.
GeyserPrediction
CastleGeyserTimes 22:59 ± 1 hour
GrandGeyserTimes 20:04 ± 1 hour
Old FaithfulGeyserTimes 17:17 ± 13 minutes

Predictions courtesy of:

GeyserTimes GeyserTimes
NPS National Park Service

(*) Prediction derived from double interval