An eruption of Grand Geyser, the tallest predictable geyser in the world, occurs every 7 - 15 hours. A classic fountain geyser, Grand erupts from a large pool with powerful bursts rather than a steady column like Old Faithful. An average eruption lasts 9 - 12 minutes and consists of 1 - 4 bursts, sometimes reaching 200 feet (60m).

During the summer, you can find eruption predictions for Grand Geyser, and five other major geysers posted in the Old Faithful Visitor Education Center. Remember, the predicted eruption times are the best estimates available, because these natural features are not on a schedule.

Information provided by the National Park Service