Sun news: Low flaring but active surface

Sun news September 19: Low flaring but active surface

(11 UTC to 11 UTC)

Today’s top story: Flare production has been low over the past day, but the sun’s surface has been active, as we saw by action on the periphery. We saw gorgeous long-lasting prominences in the sun’s southeast and southwest. But an increase in flare activity is anticipated, as two active regions, AR4220 and AR4216, have now developed a gamma in their magnetic configurations. Meanwhile at Earth this weekend, we should start receiving the fast solar wind produced by the large coronal hole we reported yesterday. Accompanied by the arrival of a co-rotating interaction region (CIR), this may bring interesting geomagnetic activity – and auroras – at Earth. Stay tuned for the latest solar news.

• Flare activity: We saw only C-class flares over the past day. There was slight increase in flare production from the day before, from 10 to 12 C flares.
  • Strongest: A C3.6 from AR4220 at 15:41 UTC on September 18.
  • Other notable flares: C3.0 from AR4223 at 22.41 UTC, C2.9 from AR4220 at 7:05 UTC, and C2.3 from AR4225 at 16:22 UTC, C2.3 from AR4219 at 23:17 UTC. AR4220 was leader, producing nine out of the 12 flares of the period.
• Sunspot regions: Seven numbered active regions can be seen on the sun’s Earth-facing disk.
  • AR4216 (northwest, beta-gamma) kept its gamma while AR4220 (southwest, beta-gamma) showed growth and developed a gamma configuration and AR4223 (southeast, beta) also showed some growth.
  • The remaining regions showed stable or in decay and magnetically simple.
• Blasts from the sun? A filament erupted in the southwest at 18:06 on September 18. The coronal mass ejection (CME) produced during this event is under modeling and analysis.
• Solar wind: The corotating interaction region (CIR) and coronal hole high-speed stream (CH HSS) that triggered last weekend’s geomagnetic storms continued to weaken.
  • Solar wind speeds continued decline from 544 km/s initially in the period down to 431 km/s by the end of the period.
  • The total interplanetary magnetic field (IMF/B_t) was weak. The B_z mostly northward for most of the period and kept north oriented at the time of this writing 11 UTC on September 19.
• Earth’s magnetic field: Conditions stayed at quiet levels (Kp = 1–2) over the past day. At the time of writing (11 UTC on September 19), the Kp continues at 1.

What’s ahead? Sun–Earth forecast

• Flare activity forecast: Low activity should continue, but there’s a 35% chance of an M-class (R1–R2) flare, most likely from AR4220 (southeast) or AR4216 (northwest), both active regions with a beta-gamma configuration.
• Geomagnetic activity forecast:
  • September 19 – 20: Quiet conditions expected are anticipated through September 20.
  • September 21: Conditions might start to ramp up due to an increase in fast solar wind from a coronal hole and the arrival of a co-rotating interaction region (CIR).

Sun news September 18: A new coronal hole rotates into view

(11 UTC to 11 UTC)

As one large coronal hole rotates out of view, another has rotated in. The departing coronal hole supplied the fast solar wind that fueled powerful geomagnetic storms and resulting auroras over the weekend. Now, a new large coronal hole has appeared on the Earth-facing disk and is moving into a geoeffective (Earth-affecting) position. Will this coronal hole bring the same excitement its predecessor provided? Let’s wait and see.

• Flare activity: Solar activity stayed at low levels. The sun produced ten C-class flares over the past day.
  • Strongest: A C2.8 from AR4223 at 0:04 UTC on September 18.
  • Other notable flares: C2.4 from AR4216 at 15:41 UTC, C1.8 from AR4216 at 12:19 UTC, and C1.7 from AR4220 at 01:38 UTC. AR4220 dominated, producing six of the ten flares.
• Sunspot regions: Six numbered active regions occupy the Earth-facing disk.
  • AR4216 (northwest, beta-gamma) developed a gamma configuration. AR4221 (southeast, beta) and AR4220 (southeast, beta) both showed modest growth. AR4217 exhibited separation in its leading spots.
  • The remaining regions stayed small and magnetically simple.
• Blasts from the sun? Coronagraph imagery showed no Earth-directed coronal mass ejections (CMEs) during this period.
• Solar wind: The corotating interaction region (CIR) and coronal hole high-speed stream (CH HSS) that triggered last weekend’s geomagnetic storms continued to weaken.
  • Solar wind speeds fell from 679 km/s to 544 km/s by the end of the period.
  • The total interplanetary magnetic field (IMF/B_t) weakened. The B_z flipped between northward and southward, ending the period southward.
• Earth’s magnetic field: Conditions ranged from quiet to unsettled (Kp = 1–3). At the time of writing (11 UTC on September 18), the Kp is at 2.

Sun news September 17: Storming eases after beautiful auroral displays

(11 UTC to 11 UTC)

Earth’s magnetic field has calmed to active levels after the G3 (strong) storming at the weekend, but isolated G1 (minor) geomagnetic storms remain possible thanks to waning effects of fast solar wind from a coronal hole. Meanwhile, three new active regions rotated onto the solar disk. Plus, a long-lived prominence in the northeast continues to surge, hinting that stronger activity could rotate into view in the coming days. Stay tuned.

• Flare activity: Solar activity stayed at low levels, with ten C-class flares recorded over the past day.
  • Strongest: AR4220 and AR4223 shared the honors for most powerful flare, each producing a C3.8. AR4220 fired its C3.8 at 13:14 UTC on September 16, while AR4223 flared at 14:42 UTC the same day.
  • Other notable flares: C3.5 from AR4223 at 14:03 UTC, C3.6 from AR4220 at 11:58 UTC, and C3.2 from AR4223 at 12:42 UTC. AR4223 dominated, producing six of the ten flares in this period.
• Sunspot regions: The Earth-facing side of the sun now hosts eight numbered regions.
  • AR4220 (northeast, beta), AR4221 (southeast, beta), and AR4224 (southeast, beta) showed modest growth with new intermediate spots.
  • Three newcomers rotated into view: AR4223, AR4224, and AR4225.
  • The rest of the regions remained small and magnetically simple.
• Blasts from the sun? Coronagraph imagery revealed no Earth-directed coronal mass ejections (CMEs) during this period.
• Solar wind: The corotating interaction region (CIR) and coronal hole high-speed stream (CH HSS) that triggered this weekend’s storms continued to drive elevated conditions.
  • Solar wind speeds dropped from 760 km/s to 642 km/s by the end of the period.
  • The total interplanetary magnetic field (IMF/B_t) weakened, while the B_z stayed strongly northward for much of the day before flipping sharply south at the close of the period.
• Earth’s magnetic field: Conditions ranged from unsettled to active (Kp = 2–4), with Kp = 3 in place at the time of writing (11 UTC on September 17).

Sun news September 16: Vivid auroras at the weekend, disturbance remains

(11 UTC to 11 UTC)

Earth’s magnetic field lit up with a surprise G3 (strong) geomagnetic storm overnight on September 14-15, triggering vivid auroras even down to mid-northern latitudes. The disturbance was the result of a knot of solar winds known as a corotating interaction region (CIR) reaching Earth, as well as a fast solar wind stream from a coronal hole (CH HSS). And, although the intense storming has subsided, G1 (minor) storms continued into early this morning. Plus, the solar wind’s magnetic orientation (Bz) is currently southward, which helps power auroral displays. So more light shows are possible at high latitudes tonight.

• Flare activity: Solar activity stayed at low levels with several small C-class flares.
  • Strongest: C3.5 from AR4213 just over the southwest limb at 18:31 UTC on September 15.
  • Other events: C2.5 from AR4217 at 4:58 UTC on September 16; C1.8 from AR4217 at 3:04 UTC on September 16. Flaring came mostly from AR4216 and AR4217 on the east, and AR4213 beyond the limb.
• Sunspot regions: Six active regions are visible.
  • AR4216 (northeast, beta) showed slight growth with new intermediate spots.
  • AR4217 (southeast, beta) rotated further into view and produced several small flares.
  • AR4213 (just beyond the southwest limb) still flared strongly despite being out of sight.
  • Other regions stayed small and magnetically simple.
• Blasts from the sun? No Earth-directed coronal mass ejections (CMEs) were detected in coronagraph imagery during this period.
• Solar wind: Conditions spiked as the corotating interaction region (CIR) and coronal hole high speed stream (CH HSS) arrived.
  • Solar wind speeds surged to near 760 km/s before gradually dropping to the 600–700 km/s range.
  • The total interplanetary magnetic field (IMF/B_t) peaked at moderately high levels northward, while the B_z had a prolonged southward stretch from late September 15 into early September 16.
• Earth’s magnetic field: Geomagnetic activity hit G3 (strong) storm levels overnight on Sunday, then eased to unsettled and active conditions, with G1 (minor) storming this morning.

Sun news September 15: Big night for auroras last night!

(11 UTC to 11 UTC)

We had a one–two punch that sparked a surprise G3 (strong) geomagnetic storm overnight last night. The storm stemmed from what’s called a corotating interaction region (CIR), which compressed the solar wind just ahead of a negative-polarity coronal-hole high-speed stream (CH HSS). And this combo caused solar wind speeds to jump to ~650 km/second. Read more about the solar wind last night below. High-latitude sky watchers reported intense displays! And even mid-latitudes were seeing periods of auroral activity as the storm peaked.

• Flare activity: Solar flaring stayed low with small C-class events dominating.
  • Strongest: C3.8 from AR4217 at 15:23 UTC on September 14.
  • Other C flares (selection): C2.6 at 15:14 UTC (AR4217) and C2.1 at 11:56 UTC (AR4217). AR4217 produced most of the day’s activity as it rotated into view.
• Sunspot regions: We now see four active regions on the sun’s Earth-facing disk.
  • AR4217 (southeast limb, emerging) — lead producer with multiple C flares as it rotated into view.
  • AR4216 (northeast, beta) — added small intermediate/trailer spots and produced low-level C flares early.
  • AR4218 (northwest, beta) — newly numbered; simple structure so far.
  • A small unnumbered area near N04E78 is rotating in.
• Blasts from the sun? Multiple coronal mass ejections (CMEs) lifted off the east limb following C flares in AR4217 and a filament eruption near S23E68. Analyses indicate no Earth-directed components. Learn more: What is a CME?
• Solar wind: A classic CIR-then-HSS arrival drove the storm.
  • Speed rose from ~320 km/s to ~650 km/s after ~23:00 UTC September 14.
  • Total interplanetary magnetic field (IMF) peaked at moderately high levels; B_z oscillated between north and south with sustained southward intervals that opened Earth’s magnetosphere.
• Earth’s magnetic field: Conditions jumped from quiet–unsettled to a G3 (strong) storm during the CIR/CH HSS transition. Expect lingering geomagnetic activity as fast wind persists. Check the real-time Kp index for updates.

Sun news September 14: Fast solar wind incoming, auroras possible

(11 UTC to 11 UTC)

Flaring remained at low levels over the past day, with the sun producing only small C-class and B-class flares. But changes are brewing: a fast solar wind stream from a coronal hole is heading toward Earth. Combined with possible weak influence from a CME launched on September 11, these conditions could bring G1 (minor) geomagnetic storms later today and tomorrow. Sky watchers at high latitudes should be on aurora alert.

• Flare activity: Solar activity stayed at low levels with nine flares recorded in the past 24 hours: six C-class and three B-class.
  • Strongest: C2.2 from AR4216 at 06:50 UTC on September 14.
  • Other notable events: C1.7 (S16E87 at 06:11 UTC), C1.4 (S14E87 at 08:04 UTC). AR4216 produced several of these faint flares after rotating further into view.
• Sunspot regions: Four active regions are visible on the Earth-facing disk.
  • AR4213 (southwest, beta) developed intermediate spots but showed decay in its trailing portion.
  • AR4216 (northeast limb, beta) emerged with a simple bipolar structure and became the most active flare producer of the day.
  • AR4211 (southwest, alpha) remained stable and magnetically simple.
  • Other small regions decayed or stayed quiet with little magnetic complexity.
• Blasts from the sun? No Earth-directed coronal mass ejections (CMEs) appeared in coronagraph imagery. A faint filament eruption lifted off the southeast quadrant early on September 13, but models suggest it will miss Earth, passing just south and east on September 16.
• Solar wind: Solar wind conditions weakened, with speeds dropping from 375 km/s to 350 km/s and the interplanetary magnetic field (IMF) strength is low. The Bz component varied weakly between north and south.
• Earth’s magnetic field: Earth’s field was quiet to unsettled yesterday. Forecasts call for G1 (minor) storms today as the fast wind stream reaches Earth, with unsettled-to-active conditions likely through September 16. There’s also a chance for weak effects from the September 11 CME as it passes nearby.

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Bottom line: Sun news September 19, 2025: Filament action and fiery prominences in the south hemisphere. This weekend fast solar wind may reach us at Earth.