In some small geysers, the eruption process can take just a few minutes. In larger geysers, it can take days. The most famous geyser in the United States, Yellowstone National Park's Old Faithful, erupts about every 50-100 minutes.

Geyser eruption frequencies vary wildly across the globe, ranging from every few minutes to several years, depending on the specific "plumbing" and heat source of the geyser. Old Faithful in Yellowstone is famous for its predictability, erupting approximately every 94 minutes (plus or minus 10 minutes) in 2026. In contrast, the world's tallest active geyser, Steamboat Geyser, is famously erratic, with intervals ranging from 3 days to over 50 years. Some smaller geysers, like those in the El Tatio field in Chile or the Strokkur geyser in Iceland, are much more frequent; Strokkur typically erupts every 6 to 10 minutes, often in quick successions of up to six bursts. Many geysers are considered "dormant" until a seismic event or change in the water table triggers a new active cycle. These natural "steam explosions" are delicate balancing acts of underground pressure and temperature, meaning even a small earthquake or a heavy rain season can permanently alter their schedules, making the study of their periodicity a constant and fascinating challenge for volcanologists.