Multiple coronal mass ejections (CMEs) linked to repeated eruptions from Active Region 4479 are forecast to reach Earth in stages from July 3 through 6. NOAA’s Space Weather Prediction Center (SWPC) forecasts G1 – Minor to G2 – Moderate geomagnetic storm conditions from July 3 into 4 from the CME associated with the June 30 X1.1 flare, while later CME arrivals still remain under model assessment.
Space weather physicist Dr. Tamitha Skov described the activity as a “Machine-Gun Sun,” saying more than five solar storms are headed toward Earth and that the first could arrive before 12:00 UTC on July 3. Skov said geomagnetic conditions above G2 would depend on the magnetic orientation of the arriving CMEs.
NASA’s Community Coordinated Modeling Center (CCMC) CME Scoreboard listed six active CME entries on July 2, with modeled shock-arrival estimates spanning July 3 through 6. The entries include eruptions associated with M1.4, X1.1, M1.0, M3.5, and M4.2 flares, as well as a June 30 eruption from or near the same active region complex.
The earliest modeled arrivals are related to a CME associated with the M1.4 flare at 21:40 UTC on June 29 and the full-halo CME produced by the X1.1 flare at 20:50 UTC on June 30.
CCMC’s model entries placed their median arrival times at 11:00 UTC and 05:39 UTC on July 3, respectively. NOAA’s official July 2 forecast expects the June 30 CME early on July 3 and calls for G1–G2 geomagnetic storm conditions through July 4.
A further CME linked to an eruption beginning near 13:30 UTC on June 30 has a modeled arrival at 18:00 UTC on July 5. CCMC also lists a CME associated with an M3.5 flare from Region 4479 at 19:43 UTC on July 1, with an average arrival estimate near 11:59 UTC on July 5.
A faint CME associated by CCMC with an M1.0 flare at 11:25 UTC on July 1 has a median arrival estimate near 21:50 UTC on July 5. However, an OSPREI model run for the same entry places the arrival at 07:41 UTC on July 6.
SWPC’s Forecast Discussion issued at 12:30 UTC on July 2 includes a slow-moving CME with an Earth-directed component after an M1.3 flare at 10:08 UTC on July 1. The agency associated a later CME, first observed in coronagraph imagery near 02:36 UTC on July 2, and presumed source to a long-duration M4.2 flare from Region 4479.
SWPC modeling forecasts that the later CME will catch up to and overtake the earlier Earth-directed CME, with arrival expected from late July 5 to early July 6.
CCMC’s M4.2-associated CME entry used an arrival estimate of 02:00 UTC on July 5, with a seven-hour uncertainty range on either side and a modeled maximum Kp range of 4–6.
The NOAA and CCMC records use different flare associations for closely timed July 1 activity. SWPC linked its slow Earth-directed CME to an M1.3 flare at 10:08 UTC, while CCMC listed a separate faint CME as most likely associated with an M1.0 flare at 11:25 UTC.
Geomagnetic conditions remained quiet to unsettled before the July 3 forecast window, with the highest observed three-hour Kp during the preceding 24 hours at 3, below NOAA storm levels.
NOAA’s active G2 Geomagnetic Storm Watch, issued at 09:35 UTC on July 2 and superseding all prior watches, forecasts moderate geomagnetic storm conditions on July 3 and 4.
Potential effects are expected mainly poleward of 55° geomagnetic latitude and include power-grid fluctuations, voltage alarms in high-latitude systems, satellite orientation irregularities and increased drag on low-Earth-orbit satellites, degraded high-frequency radio propagation at high latitudes, and aurora as far south as New York, Wisconsin, and Washington state.
References:
1 Forecast Discussion – NOAA/SWPC – Issued at 12:30 UTC on July 2, 2026