How often does Old Faithful erupt?

Old Faithful is one of the most famous natural wonders in the world, celebrated for its remarkably consistent schedule of eruptions. Located in the Upper Geyser Basin of Yellowstone National Park, this iconic geyser has drawn visitors for generations because of its dependable behavior, powerful displays, and the unique window it provides into the park’s immense geothermal system. While many geysers are unpredictable and can go dormant for years, Old Faithful continues to erupt regularly, making it a symbol of Yellowstone’s volcanic energy and a favorite spectacle for millions of travelers each year.

Quick Reference: Old Faithful Eruption Frequency

Topic	Quick Facts
Average Eruption Interval	Roughly every 90 minutes on average
Shorter Intervals	Around 60–65 minutes after shorter eruptions
Longer Intervals	Around 90–110 minutes after longer eruptions
Prediction Accuracy	Park rangers can predict eruptions with about 90% accuracy
Duration of Eruption	1.5 to 5 minutes
Height of Eruption	100 to 180 feet
Best Viewing Strategy	Arrive 20–30 minutes before predicted time
Peak Visiting Seasons	June through September
Best Time for Less Crowd	Early morning or late evening
Visitor Center Predictions	Updated forecasts available at Old Faithful Visitor Education Center
Seating & Facilities	Large seating area, viewing deck, food, gift shops & restrooms nearby

Old Faithful erupts roughly every 60 to 110 minutes, although the exact interval between eruptions varies depending on the duration and strength of the previous eruption. Shorter eruptions typically last around a minute and are followed by shorter waiting periods of about 60 to 70 minutes. Longer eruptions, which can last over 4 minutes, require much more time for the underground system to recharge, extending the interval between eruptions to ninety minutes or more. This predictable window is what allows park rangers and scientists to forecast the next eruption time with impressive accuracy, usually within a ten-minute range.

The reason Old Faithful can erupt so reliably is due to its unique underground plumbing system. Deep beneath the surface, rainwater and snowmelt seep downward through porous rock until they meet heat from the Yellowstone volcano’s enormous magma chamber. This water becomes superheated well above the boiling point but remains liquid because of the immense pressure underground. As the pressure increases, steam and hot water are eventually forced upward through Old Faithful’s narrow conduit. When the pressure becomes too great to hold, it releases all at once, resulting in the spectacular eruption that shoots boiling water and steam up to one hundred to one hundred eighty feet into the air.

Although Old Faithful is consistent, it is not perfectly exact, and its eruption pattern has changed over time. Natural events such as earthquakes can alter the internal plumbing and either shorten or lengthen eruption intervals. For example, the 1959 Hebgen Lake Earthquake significantly changed timing patterns throughout the Upper Geyser Basin. Seasonal groundwater levels, snowmelt, and long-term geological changes can also affect how frequently eruptions occur. However, even with these variations, Old Faithful remains one of the world’s most predictable geysers and continues to demonstrate the dynamic nature of Yellowstone’s landscape.

For visitors planning to witness an eruption, the experience is easily accessible. Rangers post predicted eruption times at the Old Faithful Visitor Education Center and at various signs around the viewing area. Because Old Faithful draws large crowds, guests often arrive early to find a good viewing spot and enjoy the anticipation building among those gathered. The display is unforgettable: the deep rumble below the earth, the sudden burst of water, and the tower of steam drifting into the crisp mountain air represent one of the most powerful interactions between geology and natural beauty that a person can witness.