Kilauea volcano has gone quiet again, but not for long. The U.S. Geological Survey’s Hawaiian Volcano Observatory expects the next round of lava fountaining at the Big Island summit to begin sometime between Monday, May 5, and Thursday, May 8, 2026, based on the steady re-inflation of the crater floor detected by tiltmeters buried near Halema’uma’u.
The forecast, published in HVO’s May 2 daily update, narrows an earlier projection that had stretched through May 9. That one-day trim reflects fresh tilt data showing magma is accumulating beneath the summit at a pace consistent with a mid-week return of fountaining. The observatory labels the coming burst episode 46 in a sequence that stretches back to December 2024 and has produced 45 completed episodes of high-intensity fountaining, all confined to Halema’uma’u crater inside Hawai’i Volcanoes National Park.
What episode 45 looked like
The most recent eruption ran 8.5 hours on April 23, starting at 1:34 a.m. HST and ending at 10:01 a.m., according to HVO’s status report for the episode. The north vent drove the show, sending molten rock skyward in sustained fountains, while the south vent produced only gas jetting and visible flame but no true fountaining.
That split behavior between the two vents has become a recurring feature of the eruption cycle. It tells scientists that magma pressure is not distributing evenly beneath the crater floor and that shallow pathways in Kilauea’s plumbing system open and close between bursts. Which vent dominates matters for hazard planning: it determines where spatter piles up, how high fountains reach, and how far tephra travels downwind.
For a sense of scale, the preceding episode 44 launched fountains to roughly 240 meters (about 800 feet) and pushed a volcanic plume to approximately 15,000 feet, according to HVO reporting on that event. Large chunks of tephra rained down on areas near the crater, prompting park closures and safety advisories. That episode also overlapped with the Merrie Monarch Festival, one of the Big Island’s most important cultural gatherings, a reminder that Kilauea’s rhythm ripples well beyond the park boundary and into daily life, tourism schedules, and air quality across the island’s leeward side.
Why the forecast window could still shift
HVO has been upfront that its timing projections are based on tilt trends, not certainties. The observatory’s own record proves the point: the April 30 projection ran one day longer than the updated May 2 estimate, and earlier episodes in this sequence have arrived both ahead of and behind schedule.
Tiltmeters capture the slow swelling of the summit as magma pools underground, but the exact moment pressure exceeds the threshold for fountaining depends on variables that instruments cannot fully resolve: small shifts in conduit geometry, changes in gas content, or subtle fractures in rock that open new pathways. HVO has not published a forecast for episode 46’s duration, fountain height, or erupted volume. Episode durations across the 45 completed bursts have ranged from a few hours to the better part of a day, so there is no reliable template for what comes next.
Air quality and the question of how long this goes on
During active fountaining, communities downwind of the summit typically contend with elevated levels of vog, the volcanic smog created when sulfur dioxide reacts with moisture and sunlight. Vog can aggravate asthma, heart conditions, and other respiratory problems, and it reduces visibility across wide stretches of the island. During pauses like the current one, conditions generally improve, but residual degassing from open vents means the air does not fully clear.
HVO’s public notices for the current pause do not include specific sulfur dioxide emission rates or real-time air quality measurements. The National Park Service has confirmed the eruption remains ongoing and has issued visitor advisories for May 2026, urging people to check conditions before entering the park and to avoid areas downwind of active vents. Residents and visitors can monitor real-time air quality through the Hawaii Department of Health’s monitoring network and the EPA’s AirNow system.
A broader question looms behind each new episode: how long will this cycle continue? HVO describes the December 2024-to-present activity as a summit eruption confined to Halema’uma’u, but the observatory has not signaled a clear endpoint or a transition to a different eruptive style. Kilauea has shifted gears before, and nothing in the current monitoring data suggests a similar migration is imminent, but scientists stress that the volcano remains active even during pauses and that future episodes should be expected as long as magma keeps feeding the summit reservoir.
What residents and visitors should do before May 5
For anyone on the Big Island or planning a visit to Hawai’i Volcanoes National Park, the practical message from HVO is straightforward: treat the May 5 through May 8 window as a period of elevated readiness. That means checking the observatory’s daily updates each morning, following National Park Service advisories on trail and overlook closures, and staying clear of areas where tephra could fall.
People with respiratory conditions should have medication accessible and monitor air quality reports closely once fountaining resumes. Drivers on highways near the park should be prepared for reduced visibility from vog and volcanic haze, particularly in the hours immediately after an episode begins.
Kilauea has been putting on one of its most sustained summit performances in years. Episode 46 will add another chapter, but exactly when it starts, how high the fountains reach, and how long the show lasts are questions only the volcano can answer.
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*This article was researched with the help of AI, with human editors creating the final content.
