Spectacular Volcanic Eruption Prompts National Weather Service to Issue Rare Ashfall Advisory

The Kilauea Volcano had its 48th eruption today in the current eruption series which began in 2025. Image: USGS

The Kilauea Volcano on the Big Island of Hawaii today erupted in spectacular fashion, shooting red hot lava high into the sky. With volcanic matter being ejected high into the air, quickly cooling, and returning to the surface as volcanic fallout, the National Weather Service on Oahu in Honolulu issued a rare Ashfall Advisory for eastern portions of the Big Island. Today’s eruption was a record for Kilauea, with now 48 eruption episodes documented in the latest eruption event that kicked off in 2024.

Episode 48 of the Kīlauea summit eruption in Hawai‘i Volcanoes National Park stopped at 1:37 pm local time, today, June 1 after 9 hours of lava fountaining. According to USGS, this eruption has now surpassed the number of fountaining episodes in the opening years of the Puʻuʻōʻō eruption from 1983-1986 , setting a new record number of fountaining episodes in any one Kīlauea eruption.

Tephra is anything erupted by a volcano that travels through the air before it is deposited on the ground. Lava fountaining episodes at the summit of Kīlauea since December 2024 have deposited glassy and lightweight tephra at various locations around Kīlauea summit and farther downwind, depending on the lava fountain heights and wind conditions. During episode 44, tephra landed to the north/northeast of the eruptive vents. This photo shows a fist-sized piece that landed near Kilauea Military Camp in Hawaiʻi Volcanoes National Park, where tephra fall was most dense and nearly continuously covered the ground surface. Image: USGS / K. Mulliken

Lava flowed from the south vent about 95 times in the days before episode 48, but only the north vent produced a lava fountain of up to 650 feet tall during the episode. This pattern has been followed during the past several episodes. USGS says that an estimated 7.3 million cubic yards of lava spilled across Halemaʻumaʻu at the summit of the volcano.

Today’s eruptive plume rose to about 24,000 ft above sea level; higher level winds from the south caused tephra to fall north and east of Kīlauea’s caldera at overlooks within Hawaiʻi Volcanoes National Park, as well as on Highway 11 near Nāmakanipaio Campground, Volcano Village, Mauna Loa Estates, and Ohia Estates.

With volcanic fall-out returning to the surface, the National Weather Service issued a relatively rare Ashfall Advisory for eastern potions of the Big Island from just north of Hilo to the southernmost point of the United States at South Point.

The National Weather Service said that while the Kilauea eruption has ended, the Ashfall Advisory would continue through 6pm local time tonight. They wrote, “Please remember fine ash and Pele`s hair may continue for hours after the eruption stops. Winds will continue to remain variable through 20,000 ft in elevation, causing tephra fallout to vary in location.”

During the 2018 eruption of Kilauea, the National Weather Service in Honolulu created special products to keep the public informed of the risks posed by the possible ashfall from Hawaii’s most active volcano. . NOAA meteorologist John Bravender, who works at the Honolulu office of the National Weather Service, told us then how they’ve developed the advisories.

Tephra is an additional hazard from volcanic eruptions. With a Kona Low, this could be especially problematic on the Big Island of Hawaii with tephra falling on population centers rather than just the park area due to a shift in typical wind patterns. Image: USGS — Tephra is an additional hazard from volcanic eruptions. Shifting wind patterns could bring volcanic fall-out far from Hawaii Volcanoes National Park to communities around the eastern side of the Big Island. Image: USGS

“The volcanic ashfall program is something we’ve been working on quite fast over the past week or two. As the weather forecast office, we’ve had responsibility for issuing SIGMET and aviation warnings but given the past history from our volcanoes, haven’t really been really concerned about ashfall. ” Bravender said the team there has had a “crash course” of sorts to develop a program, relying on experts from other groups such as Hawaiian Volcano Observatory (HVO) and the Alaska Aviation Weather Unit. But unlike severe weather watches that are issued ahead of other severe weather events, you won’t see an Ashfall Watch posted. “There’s no watches; these are very reactive products, ” Bravender told us.

When an ashfall incident is imminent due to some type of explosion at the volcano, the National Weather Service office in Honolulu will issue one of three types of products. The first is a Special Weather Statement. A Special Weather Statement is issued when there is the potential for trace amounts of accumulating ash. When there’s a chance of a more significant ashfall, from over a trace to up to 1/4″, the National Weather Service will then issue an Ashfall Advisory. And if a heavy ashfall is expected with accumulations greater than 1/4″, an Ashfall Warning is issued.

When any of these products are issued, the National Weather Service encourages people to avoid ash. “Avoid excessive exposure to ash which is an eye and respiratory irritant,” the Special Weather Statement text reads. “Those with respiratory sensitivities should take extra precaution to minimize exposure.”

USGS kept the Kīlauea alert level/aviation color code at WATCH/ORANGE throughout the episode because fallout was not extensive and did not last very long. After the episode ended, USGS lowered Kīlauea to ADVISORY/YELLOW reflecting that volcanic activity had decreased significantly but continues to be closely monitored for possible renewed increase.

In the U.S., the USGS and volcano observatory units are responsible for issuing Aviation Codes and Volcanic Activity Alert Levels. Aviation Codes are green, yellow, orange, or red. When ground-based instrumentation is insufficient to establish that a volcano is at a typical background level of activity, it is simply “unassigned.” While green means typical activity associated with a non-eruptive state, yellow means a volcano is exhibiting signs of elevated unrest above known background levels. When a volcano exhibits heightened or escalating unrest with the increased potential of eruption, it jumps to orange. Finally, when an eruption is imminent with significant emission of volcanic ash expected in the atmosphere or an eruption is underway with significant emission of volcanic ash into the atmosphere, the code becomes red. Volcanic Activity Alert levels are normal, advisory, watch, or warning. As with aviation codes, if data is insufficient, it is simply labeled as “unassigned.” When the volcano is at typical background activity in a non-eruptive state, it is considered normal. If the volcano exhibits signs of elevated unrest above background level, an advisory is issued. If a volcano exhibits heightened or escalating unrest, a watch is issued while a warning is issued when a hazardous eruption is imminent.

Kilauea has been erupting episodically since December 23, 2024 from two vents in Halema‘uma‘u. Lava fountaining episodes, which generally last for less than 12 hours, are separated by pauses that can be longer than three weeks.

USGS says that Kīlauea summit region inflation since the end of episode 48 indicates that another fountaining episode is possible; but they need more time to collect data to generate the model to forecast episode 49, which will set a another new record for Kīlauea.