The floor of Halemaʻumaʻu crater has been quiet for nine days, but the ground above Kilauea’s shallow magma reservoir is swelling again. The Hawaiian Volcano Observatory now forecasts that lava fountains will return to the summit crater between Sunday, May 25, and Tuesday, May 27, 2026, marking what would be episode 48 of an eruption sequence that began on December 23, 2024, and has been running for nearly 17 months.
The forecast, published in the observatory’s daily Kilauea updates, is built on tilt and GPS inflation data collected across all 47 previous episodes. Each cycle follows the same basic script: lava fountains erupt, the summit deflates rapidly, the eruption pauses, and then magma refills the reservoir until pressure triggers the next episode. By comparing the current reinflation curve against dozens of prior cycles, HVO scientists can estimate when the system will reach its breaking point again.
What happened during episode 47
Episode 47 began at 3:27 p.m. HST on May 14 and ended abruptly at 12:27 a.m. on May 15, lasting roughly nine hours. Within minutes of the onset, the National Weather Service in Honolulu issued a special weather statement after radar detected ash and tephra rising to approximately 8,000 feet above ground level. Trade winds carried the material to the southwest, raising the possibility of light ashfall in downwind communities and brief visibility reductions along nearby roadways.
The observatory’s formal hazard notification for the episode documented effusion rates, total erupted volume, maximum fountain height, and tephra impacts, though HVO noted that several figures remain preliminary pending further analysis. The episode fit the now-familiar pattern: rapid onset, vigorous fountaining confined to the deep basin of Halemaʻumaʻu, and an equally rapid shutdown. Summit reinflation began almost immediately afterward.
Throughout the eruption sequence, all lava activity has remained within a closed section of Hawaiʻi Volcanoes National Park. No flows have threatened communities outside the summit region.
How the forecast works
Think of Kilauea’s summit reservoir as a balloon being slowly inflated from below. As magma rises from depth and pools in the shallow chamber, tiltmeters on the crater rim record a smooth upward trend in ground deformation. Once pressure reaches a threshold, lava breaks through at the summit vent, fountains erupt, and the tilt signal drops sharply. The observatory has watched this cycle repeat 47 times, giving scientists an unusually rich dataset for calibrating short-term eruption forecasts.
The three-day window for episode 48 reflects where the current inflation trend sits relative to those past cycles. If reinflation accelerates, the eruption could arrive at the early end of the window or even sooner. If it stalls, the onset could slip later. A sudden shift in magma supply or a small intrusion into a different part of the summit plumbing could also delay or cancel the expected episode entirely.
Real-time tilt values are referenced in daily updates but have not been published as specific numbers during this reporting cycle, which means the public must rely on HVO’s qualitative descriptions of “steady” or “accelerating” inflation rather than raw data. The observatory has said it will continue to narrow the forecast window as new measurements come in over the next 48 to 72 hours.
What the maps show, and what they don’t
The most recent published reference map of the eruption site is based on a helicopter overflight conducted on March 31, 2026, covering cumulative lava deposits through episode 43. That map shows a thick, perched lava surface and a growing spatter cone around the main vent. Four additional episodes of lava accumulation have occurred since then, meaning the crater floor is almost certainly higher and more uneven than the last published contours indicate. Updated topographic surveys and tephra-fall maps have not yet appeared in publicly available USGS products.
What to watch for this weekend
Sulfur dioxide emissions spike during active fountaining episodes and are one of the primary health concerns for communities downwind of the summit. Volcanic haze, known locally as vog, can irritate eyes and airways, particularly for people with asthma or other respiratory conditions. During pauses between episodes, SO2 output typically drops but does not disappear entirely.
If episode 48 begins within the forecast window, the National Weather Service will issue statements based on real-time radar and satellite imagery. Wind direction at the time of eruption will determine where ash and Pele’s hair fall. No advance ashfall forecast specific to this window has been issued yet, because conditions depend on the actual onset time and prevailing winds at that moment.
The Washington Volcanic Ash Advisory Center, which monitors airborne ash hazards for aviation, provides an independent cross-check on plume heights and particle dispersal. For episode 47, the roughly 8,000-foot detection was consistent with the short, vigorous fountain events that have characterized this sequence, well below the altitudes associated with larger explosive eruptions.
Kilauea’s volcanic alert level has remained at WATCH, with an aviation color code of ORANGE, for most of the eruption sequence. Those designations indicate heightened or escalating unrest with increased potential for eruption, or an eruption underway with limited hazards.
Visiting the park during the forecast window
Hawaiʻi Volcanoes National Park remains open for general visitation outside the Halemaʻumaʻu closure zone. If fountaining resumes, visitors may see glow from overlooks along Crater Rim Drive, and light ashfall or vog is possible at popular viewpoints when winds blow from the summit.
Checking the observatory’s daily updates before traveling to the park is the single most useful step visitors can take. The forecast window will narrow as new tilt data arrives, and the park may implement temporary viewpoint closures or traffic controls if conditions warrant. Visitors with respiratory sensitivities should carry masks and monitor air-quality advisories, especially during and immediately after an active episode.
Why 47 episodes matter for the next one
Each pause-and-eruption cycle tests HVO’s forecasting models against reality, revealing how closely the summit’s behavior follows its recent patterns and where it diverges. Over 17 months, those comparisons have sharpened both the timing predictions and scientists’ understanding of how much magma moves through the system during each event.
Whether episode 48 arrives on Sunday or slips past the forecast window, the observatory’s track record across this sequence will shape how confidently it can predict the episodes that follow. For the communities around Kilauea and the thousands of visitors who arrive at the park each week, that growing predictive skill translates directly into better warnings, clearer communication, and more informed decisions about when and how to safely watch one of the most active volcanoes on Earth.
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*This article was researched with the help of AI, with human editors creating the final content.
