Volcanic ash is two problems under one name: ash in the flight levels, aviation’s problem, and ash on the ground, yours.
How to read the advisory cards above
They list the Washington VAAC advisories from the previous 24 hours; the timestamp is the last refresh.
Counts measure duration, not violence. NOAA re-issues at least every six hours while a volcano is ash-active, sooner when new ash appears: a long-lived weak plume out-counts one short violent paroxysm, so a high number means ash persisted, not that anyone is in danger.
EST is not softer news, and NOT IDENTIFIABLE is not an all-clear. An estimated advisory usually means cloud blocked the satellite: VA EMS NOT OBS ON STLT DUE TO HVY WX CLD CVR BUT WEBCAM SHOWS FRQT EMS MVG NNW. One Santa María advisory reporting VA NOT IDENTIFIABLE FM STLT DATA closed with NEW VA EMS LIKELY AT ANY TIME.
“Quiet” and “unknown” differ. Quiet means the listing was read and showed no advisory; unknown means it could not be fetched.
VAAC advisory vs INSIVUMEH boletín
The Washington VAAC, run 24/7 by NOAA’s Satellite Analysis Branch, issues “real-time advisories that keep aviation safe from volcanic ash hazards” for “airline pilots, dispatchers, air traffic controllers and other users”. ICAO’s Doc 9766 lists the recipients as meteorological watch offices, area control centres and flight information centres — no general-public addressee appears anywhere in that list.
INSIVUMEH answers the ground question. Its Boletín Vulcanológico Diario appears each morning around 07:00, with special bulletins per volcano — BEFGO (Fuego), BESAN (Santiaguito), BEPAC (Pacaya), BEAGU (Agua, lahars only) — and it names the villages receiving ash. No VAAC advisory does.
Its last page addresses six institutions separately: DGAC (aviation), CONRED (disaster), INGUAT (tourism), the Municipalidad de Quetzaltenango, Acatenango and Alotenango, and San Vicente Pacaya — one audience versus six. INSIVUMEH observes and advises; CONRED issues the public instructions: INSIVUMEH’s guidance is written to SE-CONRED, warning that ash on “roofs, patios, roads, crops and vegetation” near Fuego “can cause serious damage to the eyes and respiratory tract.”
Which volcano threatens what
Three volcanoes produce Guatemala’s ash advisories — Fuego, Santiaguito and, historically, Pacaya:
| Year | Fuego | Santa María (Santiaguito) | Pacaya |
|---|---|---|---|
| 2023 | 1,088 | 305 | 0 |
| 2024 | 1,347 | 668 | 0 |
| 2025 | 751 | 913 | 0 |
| 2026 to 12 Sep | 1,100 | 530 | 0 |
Counts from the VAAC’s yearly archives. Santiaguito out-issued Fuego in 2025, 913 to 751 — watch only Fuego and you miss the volcano that was ash-active more often. INSIVUMEH is the source that names who gets dusted: its 11 September 2026 bulletin put Santiaguito’s ash west and southwest about 20 km, onto Loma Linda and San Marcos Palajunoj. Which towns get dusted is the day’s wind, not distance. What an ash day does to the city-level readings is on our air quality page.
Then the inversion. Pacaya has issued zero advisories since 2021 — the Smithsonian records its eruption as having run 7 June 2015 to 13 August 2021 and ended, while Fuego’s (2002) and Santiaguito’s (1922) continue. Yet Pacaya is the volcano that closes Guatemala City’s airport: it “lies directly in-line and only 23 km S of the N10°E-oriented airstrip”, so its smaller plumes “easily enter the path of landing aircraft.” Episodic, not dormant: 2021 alone produced 238 advisories.
The La Aurora closure record
| Date | Volcano | Duration per the source | Ordered by |
|---|---|---|---|
| 20 May 1998 | Pacaya | “closed for three days” | not found |
| 18–19 Sep 1998 | Pacaya | 35 hours, reopened “with restrictions” | not found |
| 16 Jan 2000 | Pacaya | “that evening”; reopening not found | not found |
| 27–28 May 2010 | Pacaya | 5 days — longest on record | “Civil Aviation authorities” |
| 3–4 Jun 2018 | Fuego | disputed, see below | DGAC |
| 23–24 Mar 2021 | Pacaya | 10:00 to 07:00 next day (~21 h) | DGAC and CIV |
| 11 Dec 2022 | Fuego | “algunas horas”, mid-morning to 11:00 | DGAC |
For 2023 and 2024 no closure was found in any source searched. A 2023 closure circulates online, but nothing supports it — likely the 11 December 2022 event mis-dated. For 2018 the Smithsonian’s archive gives two durations — 14:15 on 3 June to 09:30 next morning in its weekly report, “closed for two days” in its bulletin — and we are not picking one. It logs no December 2022 closure at all — not a complete register.
A Fuego eruption is not by default a flight-disruption event: in March 2025 the US Embassy said La Aurora operations were “not affected,” and in August 2026 DGAC said operations continued normally. Confirm with your airline; routes are in our flights guide. (DGAC statements here come via CONRED, Prensa Libre or AGN.)
Ashfall precautions, and the mask question
Ash is not soot: the USGS calls it “fragments of rocks, minerals, and volcanic glass”, and “hard, abrasive, mildly corrosive, conducts electricity when wet” — while noting ashfall “rarely endangers human life directly,” the exceptions being roof collapse, clean-up accidents and traffic.
CONRED’s instructions: cover water and food containers, mask your nose and mouth, protect your eyes, close doors and windows, and avoid outdoor activity when ash concentration is considerable. Clear the roof and roof drains (reposaderas) once ashfall stops; see a health centre if symptoms appear.
The mask contradiction — stated, not resolved. CONRED’s Boletín 236-2026 (3 August 2026) says to use “mascarilla o un paño húmedo” — a mask or a damp cloth. IVHHN, with GNS Science and the USGS, says the most effective respiratory protection for adults is “a well-fitting, industry-certified facemask such as a N95 mask (also called P2, FFP2 or DS2 in different parts of the world)”; that cloth is less effective than most masks; and, flatly, that “wetting materials does not improve the ability of masks or cloth to filter volcanic ash.” CONRED is the authority Guatemalans follow; IVHHN is the research body.
Eyes: no contact lenses — IVHHN warns they “will result in corneal abrasion.” Roofs: most cannot hold more than four inches (10 cm) of wet ash, up to twice as dense as dry; never hose it down. Driving: 1 mm of ash cuts visibility and makes roads slippery — the USGS advises under 55 km/h (35 mph).
It outlasts the eruption. INSIVUMEH notes wind keeps ash suspended “for several hours or days”, and material left in the Seca, Mineral, Ceniza, El Jute and Las Lajas ravines can be remobilised as lahars by rain — stay out of them when it rains.
Today’s levels: live eruption status, volcano tracker.