Yellowstone National Park - Old Faithful Geyser Predictions (U.S. National Park Service)

All predictions are made using a formula that takes into account the length of the previous eruption. The formula used has proven to be accurate, plus or minus 10 minutes, 90% of the time.

Many webcam visitors wonder why there isn't a prediction posted first thing in the morning and why there is an outdated prediction up in the evening?

The prediction information is only posted during the open-hours of the Old Faithful Visitor Center. It cannot be posted until after the ranger at the information desk observes the first open-hours eruption of the day. The formula uses the length of the previous eruption to predict the time of the next eruption. Therefore, anyone interested in Old Faithful Geyser predictions should also be interested in the open hours of the Old Faithful Visitor Center.

If there are predictions posted outside the hours mentioned, it is due to the overtime or good will of the ranger staff at the Old Faithful Visitor Center.

The Old Faithful Visitor Center is open on the following schedule:

Summer Season
8 am to 7 pm, Mountain Time

Winter Season
9 am to 5 pm, Mountain Time

Spring & Fall Seasons
Closed

If the prediction time on the webcam photo has passed, you are looking at an outdated prediction. Please come back when the Old Faithful Visitor Center is open for future predictions. The last prediction of the day involves an eruption that occurs after the visitor center closes. It remains posted until the following morning.

All predictions are posted in Mountain Time

Mountain Time is the time stamped in the top right corner of each Old Faithful and Mammoth webcam photo. To help you figure out when Mountain Time is in relationship to your time here are some comparisons.

Mountain Time is:

Two hours earlier than Eastern Time
One hour earlier than Central Time
One hour later than Pacific Time
12 hours earlier than the time in Katmandu

Compared to Greenwich Mean Time

Since Greenwich Mean Time (also know as Coordinated Universal Time or simply Universal Time) is constant, the following comparisons hold true:

During Daylight Savings Time, Mountain Time is six hours earlier than Greenwich Mean Time.
During Standard Time, Mountain Time is seven hours earlier than Greenwich Mean Time.