A major, long-duration solar flare measuring X3.3 erupted from the Sun’s southeast limb at 03:57 UTC on October 24, 2024. The event started at 03:30 and ended at 04:28 UTC. The source is returning Region 3842.
This event was associated with a Type II Radio Emission with an estimated velocity of 610 km/s, suggesting a coronal mass ejection (CME) was produced, and a Type IV Radio Emission. Type IV emissions occur in association with major eruptions on the Sun and are typically associated with strong CMEs and solar radiation storms.
In addition, a 10cm Radio Burst lasting 12 minutes and with a peak flux of 5 900 sfu was associated with this event. A 10cm radio burst indicates that the electromagnetic burst associated with a solar flare at the 10cm wavelength was double or greater than the initial 10cm radio background.
This can indicate significant radio noise associated with a solar flare. This noise is generally short-lived but can cause interference for sensitive receivers including radar, GPS, and satellite communications.
Radio frequencies were forecast to be most degraded over SE Asia and Australia at the time of the flare.
A large CME was produced during this event, with the majority of it directed away from Earth.
The source of this event was returning Region 3842 — now numbered 3869. This region is the source of 4 X-class solar flares during its previous rotation, including the X9.0 flare on October 3, thus far the strongest solar flare of Solar Cycle 25.
The X9.0 flare on October 3 produced significant space weather effects, including a substantial CME, which led to geomagnetic storms reaching G3 – Strong levels on October 6. These storms caused widespread auroral displays visible as far south as Texas (31°N) and disruptions in satellite communications and power grid fluctuations at higher latitudes.
It’s worth noting that there was one stronger solar flare produced during this cycle, estimated at X14 on July 23, 2024 — however, this was a farside event and thus did not impact Earth directly.
This flare was not included in official rankings of the most powerful solar flares of Solar Cycle 25 due to its location on the far side of the Sun, where its effects were largely directed away from Earth. Although instruments like NASA’s STEREO spacecraft detected the flare indirectly, providing estimates of its intensity, these measurements are not as precise as those gathered from Earth-facing events.
However, it did provide valuable insights into the far-side dynamics of the Sun and the scale of energy release possible during Solar Cycle 25.
Solar flare activity is expected to be at minor to moderate solar flares (60%) with a slight chance of strong levels (10%) as more magnetically complex regions emerge in the SE part of the disk.
Unsettled to active geomagnetic field levels are expected through October 26 due to the influence of negative coronal hole high speed stream (CH84 HSS). Model guidance suggests a peak in wind speeds and therefore disturbance in the geomagnetic field on October 25 with waning influences thereafter, according to SWPC.