Australia Issues G3 Geomagnetic Storm Watch

Published on Nov 7, 2025, 1:28 pm CST

5 min read

Key points

Airservices Australia's ATFM Daily Plan cites a G3 window from the afternoon of November 7 through November 9 AEDT
NOAA has a G3 (Strong) watch active after CME activity, with timing uncertainty typical of space weather
GNSS accuracy and HF radio can intermittently degrade, especially on long or high-latitude sectors
Mitigations include small ground holds, reroutes, extra fuel, and occasional payload adjustments
Travelers on evening departures from major Australian hubs should add buffer time and monitor airline notifications

Impact

Expect GNSS Drift: Intermittent GPS inaccuracies possible November 7-9 AEDT
HF Radio Variability: HF propagation may be poor at times, affecting long-haul comms
Polar Routing Changes: Airlines may avoid higher latitudes or shift tracks
Evening Departure Buffers: Arrive earlier for red-eyes and long sectors from SYD, MEL, BNE, PER
Waiver Eligibility: Check carrier alerts for same-day change flexibility

Airservices Australia's National Operations team is flagging a Strong, G3 geomagnetic storm window from Friday afternoon, November 7, through Sunday, November 9 (AEDT). During peak intervals, satellite-based navigation can become less precise, and high-frequency, HF, radio propagation can degrade, which is most noticeable on long-haul and high-latitude routings. Expect occasional ground holds, minor reroutes, and conservative payload or fuel decisions at Sydney, Melbourne, Brisbane, and Perth, particularly around evening bank departures when flows are tight.

What changed

The Australian Space Weather Forecasting Centre and the U.S. NOAA Space Weather Prediction Center both upgraded guidance this week after multiple coronal mass ejections, CMEs, raised the probability of G3-level conditions. NOAA placed a G3 watch on the November 6-7 UTC days and subsequently reported a G3 storm in progress on November 6 UTC, noting typical uncertainty bands around exact arrival and duration, while Australia's forecast calls out potential G3-G4 intervals and warns of poor HF propagation through the November 7-9 period . Airservices' ATFM Daily Plan incorporates that outlook, time-stamping a start around 1:00 p.m. AEDT on November 7, plus or minus nine hours, through November 9, also with a ±9-hour tolerance band, which explains why effects may come in pulses rather than a clean start and stop .

How space weather affects flights

Space weather primarily touches aviation through three channels: satellite navigation and surveillance, radio communications, and radiation exposure at very high latitudes. Geomagnetic storms can push ionospheric parameters outside nominal ranges, which sometimes reduces GNSS accuracy, degrades HF radio at certain frequencies, and complicates SATCOM in polar regions. These effects are usually intermittent and manageable, but they can force procedurally conservative choices, especially at higher latitudes and on ultra-long sectors where alternative communications and navigation margins matter most .

Mitigations you may see

Airlines and air navigation service providers have a familiar toolkit for G-scale events. On the ground, they may meter departures or swap runways to maintain separation and keep acceptance rates predictable. In the air, dispatchers can file slightly longer tracks to avoid high-latitude slices, carry extra contingency fuel to preserve alternates and ETOPS reserves, bias flight levels away from the most affected ionospheric layers, and shift HF operating frequencies. Payload adjustments, when they occur, are typically small and targeted to maintain fuel margins for reroutes or holding. From a traveler's point of view, these mitigations show up as minor delays at the gate, slightly longer airborne times, or seat-map changes on very full flights, not as wholesale cancellations .

Latest developments

NOAA confirmed G3 conditions on November 6 UTC and continues to maintain a G3 watch as additional CME effects work through the magnetosphere. The agency stresses a moderate confidence in arrival windows and lower confidence in peak intensity, which is normal for CME forecasting. Australia's daily reports echo elevated risk into November 9 (AEDT), including poor-to-fair HF propagation expectations and red status indicators for solar and magnetic activity. That aligns with the timing Airservices embedded in its traffic management plan for Australia's major hubs .

Traveler advice

If you are booked on long-haul or red-eye departures between November 7 and 9 (AEDT), arrive earlier than usual, keep push-notification settings on for your airline and airport app, and expect gate-area updates rather than days-ahead schedule changes. Build extra connection time on itineraries that rely on tight, late-evening banks, and consider earlier departures if you must make a same-night long-haul. If your carrier issues a change-fee waiver for flow-control or space-weather disruptions, act quickly, since waiver windows are often limited to same-day or near-term travel. Most important, watch airline messages that ask you to re-sync mobile boarding passes after reroutes or equipment swaps, which is common in ATFM-driven operations .

Background

NOAA classifies space-weather impacts using three scales: R for radio blackouts, S for solar radiation storms, and G for geomagnetic storms, each from 1, Minor, to 5, Extreme. A G3, Strong, event can produce wide-area voltage corrections on power systems and intermittent GNSS and HF impacts at aviation latitudes. Forecast discussions routinely include uncertainty bands on both timing and intensity because CME shock arrival and coupling depend on many variables that cannot be measured perfectly far upstream. That is why operational plans, like Airservices' ATFM Daily Plan, build in buffers and are re-issued daily with adjustments as observed data comes in .

Final thoughts

The G3 geomagnetic storm watch is a caution flag, not a crisis. For most travelers, the result will be routine gate-area holds, slightly altered routings, and conservative dispatch decisions that trade a few minutes for resilience. Plan a little extra time and keep notifications on, and you will likely travel with only minor inconvenience while Australia rides out the November 7-9 window.