Predictions are shown in Mountain Time.
Eruptions cannot be predicted with absolute certainty and estimates are derived from user reports.
GeyserPrediction
CastleGeyserTimes 21:17 ± 1 hour
RiversideGeyserTimes 13:54 ± 25 minutes
GrandGeyserTimes 17:41 ± 1 hour
Old FaithfulGeyserTimes 13:53 ± 13 minutes

Predictions courtesy of:

GeyserTimes GeyserTimes
NPS National Park Service

(*) Prediction derived from double interval