The geomagnetic field was at minor to severe storm levels on September 30. Strong CIR effects associated with CH1320 and CH1321 reached Earth earlier than expected and was observed beginning at ACE just after midnight on September 30. There was no clear evidence of any CME arrival. By noon the high speed stream arrived and solar wind speed peaked above 700 km/sec. Solar wind speed at SOHO ranged between 411 and 706 km/sec, averaging 530 km/sec (+129 km/sec compared to the previous day). The high latitude magnetometer at Andenes recorded active to severe storm levels. The above 10 MeV proton flux was at background levels all day.
Solar flux density measured at 20h UT on 2.8 GHz was
187.1 -
increasing 7.5
over the previous solar rotation.
The 365 day average solar flux at 1 AU was 168.85 (183 days ago). The 81 day average solar flux at 1 AU was
155.7 (41 days ago, this is 54.8% of the total SC25 solar flux range from the max 81
day average peak on September 4, 2024 at 227.3 and an average 81 day flux of
69 at solar minimum).
SC25 365d peak:
195.9 on October 13, 2024.
The Potsdam WDC planetary A index was 76 (STAR Ap - based on the average of three hour interval ap indices: 76.0). Three hour interval K indices: 67656666 (planetary), 46656545 (Boulder), 47655766 (Andenes).
The background x-ray flux is at the class C2 level (GOES 19).
At the time of counting spots (see image time), spots were observed in 17 active regions using 2K resolution (SN: 364) and in 13 active regions using 1K resolution (SN: 240) SDO/HMI images.
AR 14226 [S09W61] decayed slowly and was mostly quiet.
AR 14228 [N07W49] decayed slowly and quietly.
AR 14230 [S10W39] lost the magnetic delta
configuration and matured with decreasing polarity intermixing observed. M
flares are still possible.
AR 14232 [N03E21] became less active as polarity intermixing
decreased. M flares are still possible.
AR 14233 [N18E23] decayed slowly and quietly.
AR 14234 [S27W19] was quiet and stable.
AR 14235 [N26E25] was quiet and stable.
AR 14236 [N09E13] gained area and has minor polarity intermixing. M
flares are likely.
AR 14237 [N15W20] decayed slowly and quietly.
AR 14238 [S14W43] emerged on September 28 and was numbered by SWPC
the next day. Based on inaccurate initial SWPC data it was at first unclear
if ARs 14238 and S11476 were the same region. The spot group matured on
September 30 and was mostly quiet.
New AR 14240 [N16E67] rotated into view on September 29 and was
numbered the next day by SWPC.
Spotted regions not observed (or interpreted
differently) by SWPC/USAF:
S11479 [N09W19] decayed slowly and quietly.
New AR S11483 [N06W06] emerged with tiny spots and caused decay in
parts of CH1320.
New AR S11484 [N14E58] emerged with tiny spots.
New AR S11485 [N21E01] was observed with tiny spots in an old
plage area.
New AR S11486 [N33E45] was observed with tiny spots in an old plage
area.
New AR S11487 [N17W63] emerged with a tiny spot.
C2+ flares
| Magnitude | Peak time (UT) | Location | Source | Recorded by | Comment |
| C2.6 | 00:09 | 14230 | GOES19 | ||
| C3.0 | 00:23 | 14230 | GOES19 | ||
| C3.4 | 00:28 | 14230 | GOES19 | ||
| M1.2 | 00:56 | 14232 | GOES19 | ||
| C2.1 | 01:50 | 14232 | GOES18 | ||
| C5.8 | 02:14 | S11463 | GOES18 | small simultaneous flare in AR 14230 | |
| C5.7 | 02:18 | 14236 | GOES18 | ||
| C4.5 | 02:25 | 14236 | GOES18 | ||
| C3.6 | 02:52 | 14236 | GOES18 | ||
| C3.1 | 03:05 | 14230 | GOES18 | ||
| C2.5 | 03:49 | 14230 | GOES18 | ||
| C2.5 | 04:25 | 14232 | GOES18 | ||
| C3.8 | 04:37 | 14236 | GOES18 | ||
| C3.6 | 04:46 | 14236 | GOES18 | ||
| C2.6 | 05:10 | 14230 | GOES18 | ||
| C2.4 | 05:36 | 14232 | GOES18 | ||
| C2.3 | 06:01 | 14240 | GOES18 | ||
| C2.5 | 06:35 | 14226 | GOES18 | ||
| C2.1 | 08:26 | 14236 | GOES19 | ||
| C2.8 | 09:21 | N10E23 | 14236 | GOES19 | |
| M2.6 | 09:40 | S17W58 (SDO/AIA) | S11463 | GOES18 | CME |
| C4.1 | 10:56 | 14230 | GOES18 | ||
| C3.7 | 11:40 | 14230 | GOES18 | ||
| C6.0 | 12:09 | 14230 | GOES18 | ||
| M1.8 | 12:27 | S11W32 (SDO/AIA) | 14230 | GOES18 | SDO/AIA location used instead of inaccurate SWPC data |
| C9.2 | 13:01 | 14226 | GOES18 | ||
| C2.5 | 16:13 | 14236 | GOES18 | ||
| C2.9 | 17:43 | 14232 | GOES18 | ||
| C2.6 | 18:49 | 14230 | GOES18 | ||
| C2.1 | 21:08 | 14230 | GOES18 | ||
| C4.0 | 21:42 | S12W58 (SDO/AIA) | 14226 | GOES18 | |
| C2.2 | 23:50 | 14226 | GOES18 |
September 28-29: No obviously Earth directed CMEs.
September 30: A partial halo CME was observed after the M2.7 flare in
AR S11463 at 09:40 UT. There is a chance of weak shock effects on October 3.
[Coronal
hole history (since October 2002)]
[Compare today's report to the situation one solar rotation ago:
28 days ago
27 days ago
26 days ago]
A trans equatorial positive polarity coronal hole (CH1320) will rotate across the central meridian on September 29 - October 1. A recurrent southern hemisphere positive polarity coronal hole (CH1321) will be Earth facing on September 29 - October 3.
The geomagnetic field is expected to be at unsettled to major storm levels on October 1 and quiet to active levels on October 2-6 due to effects from CH1320/CH1321.
| Coronal holes (1) | Coronal mass ejections (2) | M and X class flares (3) |
1) Effects from a coronal hole could
reach Earth within the next 5 days. When the high speed stream has arrived
the color changes to green.
2) Effects from a CME are likely to be observed at Earth within 96 hours.
3) There is a possibility of either M or X class flares within the next 48 hours.
Green: 0-30% probability, Yellow: 30-70% probability, Red: 70-100% probability.
(Click on image for 2K resolution).
4K resolution.
Compare to the previous day's image. 0.5K image
When available the active region map has a coronal hole polarity overlay where red (pink) is negative and blue is positive.
Data for all officially numbered solar regions according to the Solar Region Summary provided by NOAA/SWPC, all other regions are numbered sequentially as they emerge using the STAR spot number. Comments are my own, as is the STAR spot count (spots observed at or inside a few hours before midnight) and data for regions not numbered by SWPC or where SWPC has observed no spots. SWPC active region numbers in the table below and in the active region map above are the historic SWPC/USAF numbers. SWPC data considered to be not sufficiently precise (location, area, classification) are colored red.
| Active region | SWPC date numbered STAR detected |
Spot count | Location at midnight | Area | Classification | SDO / HMI 4K continuum image with magnetic polarity overlays |
Comment | ||||
|---|---|---|---|---|---|---|---|---|---|---|---|
| SWPC/ USAF |
STAR | SWPC | STAR | Current | Previous | ||||||
| 2K | 1K | ||||||||||
| 14227 | 2025.09.19 2025.09.20 |
S15W69 |
was AR S11448 location: S20W61 |
||||||||
| 14226 | 2025.09.19 2025.09.20 |
2 | 5 | 3 | S09W62 | 0090 | HSX | CAO |
 |
 |
was AR S11449 area: 0160 location: S09W61 |
| 14228 | 2025.09.20 2025.09.21 |
2 | N05W55 | 0004 | AXX |
 |
 |
was AR S11453 location: N07W49 |
|||
| S11455 | 2025.09.21 | N30W57 | |||||||||
| 14230 | 2025.09.22 2025.09.23 |
16 | 41 | 21 | S11W37 | 0190 | DAI | DKI |
 |
 |
beta-gamma was AR S11456 location: S10W39 area: 0480 |
| S11458 | 2025.09.22 | S22W52 | |||||||||
| S11460 | 2025.09.24 | S17W39 | |||||||||
| 14233 | 2025.09.25 2025.09.27 |
11 | 26 | 17 | N17E21 | 0120 | DAO | DRO |
 |
 |
was AR S11461 area: 0090 location: N18E23 |
| 14232 | 2025.09.26 2025.09.26 |
9 | 36 | 21 | N04E22 | 0250 | DHI | DKI |
 |
 |
beta-gamma was AR S11462 area: 0470 location: N03E21 |
| S11463 | 2025.09.26 | S16W66 |
 |
||||||||
| S11465 | 2025.09.26 | S08W05 | |||||||||
| S11466 | 2025.09.26 | S30W27 | |||||||||
| 14234 | 2025.09.27 2025.09.27 |
5 | 2 | S23W23 | 0010 | AXX |
 |
 |
was AR S11467 location: S27W19 |
||
| 14235 | 2025.09.27 2025.09.27 |
1 | 3 | 1 | N27E24 | 0030 | HSX | CAO |
 |
 |
area: 0060 location: N26E23 |
| 14236 | 2025.09.27 2025.09.28 |
21 | 32 | 25 | N10E14 | 0250 | DKC | DKI |
 |
 |
beta-gamma was AR S11469 area: 0750 location: N09E13 |
| S11470 | 2025.09.27 | N07W03 | |||||||||
| S11471 | 2025.09.27 | S14W45 | |||||||||
| S11472 | 2025.09.27 | S26W43 | |||||||||
| S11473 | 2025.09.27 | N02W21 | |||||||||
| 14237 | 2025.09.28 2025.09.29 |
2 | 2 | 1 | N16W19 | 0010 | BXO | BXO |
 |
 |
was AR S11474 location: N15W20 area: 0005 |
| 14238 | 2025.09.28 2025.09.29 |
7 | 21 | 12 | S14W41 | 0060 | DAO | DSI |
 |
 |
was AR S11476 area: 0230 location: S14W43 |
| S11477 | 2025.09.28 | S03W18 | |||||||||
| 14239 | 2025.09.29 | 1 | S10W41 | 0080 | HSX | SWPC data could point to the leader spot of AR 14230, however, there was never any justification for a split. This is a major misinterpretation | |||||
| S11479 | 2025.09.29 | 1 | 1 | N09W19 | 0005 | AXX |
 |
 |
|||
| 14240 | 2025.09.29 2025.09.30 |
1 | 2 | 1 | N16E67 | 0010 | AXX | HRX |
 |
 |
was AR S11480 area: 0020 |
| S11481 | 2025.09.29 | S16E01 |
 |
||||||||
| S11483 | 2025.09.30 | 6 | 2 | N06W06 | 0020 | CRO |
 |
||||
| S11484 | 2025.09.30 | 6 | 3 | N14E58 | 0025 | BXO |
 |
||||
| S11485 | 2025.09.30 | 3 | N21E01 | 0005 | AXX |
 |
|||||
| S11486 | 2025.09.30 | 2 | N33E45 | 0003 | BXO |
 |
|||||
| S11487 | 2025.09.30 | 1 | N17W63 | 0001 | AXX |
 |
|||||
| Total spot count: | 71 | 194 | 110 | ||||||||
| Sunspot number: | 171 | 364 | 240 | (total spot count + 10 * number of spotted regions) | |||||||
| Weighted SN: | 121 | 248 | 164 | (Sum of total spot count + classification weighting for each AR. Classification weighting: X=0, R=3, A/S=5, H/K=10) | |||||||
| Relative sunspot number (Wolf number): | 188 | 200 | 192 | ||||||||
| Month | Average solar flux | International sunspot number (WDC-SILSO) |
Smoothed sunspot number (4) | Average
ap (3) |
|
|---|---|---|---|---|---|
| Measured | 1 AU | ||||
| 2024.04 | 161.3 | 162.6 | 137.0 | 144.5 (+3.1) | 9.69 |
| 2024.05 | 187.7 | 191.9 | 172.1 | 149.1 (+4.6) | 23.56 (SC25 peak) |
| 2024.06 | 184.3 | 190.2 | 164.1 | 152.8 (+3.7) | 10.24 |
| 2024.07 | 196.6 | 203.0 | 196.8 | 155.0 (+2.3) | 7.13 |
| 2024.08 | 246.1 (cycle peak) |
252.2 | 216.0 (SC25 peak) | 156.8 (+1.8) | 15.96 |
| 2024.09 | 195.7 | 197.8 | 141.1 | 159.4 (+1.6) | 15.36 |
| 2024.10 | 221.0 | 219.6 | 165.8 | 160.9 (+1.5) (SC25 solar max) | 18.99 |
| 2024.11 | 199.6 | 195.3 | 154.1 | 157.1 (-3.8) | 9.33 |
| 2024.12 | 197.3 | 191.2 | 154.6 | 151.3 (-5.8) | 8.42 |
| 2025.01 | 190.3 | 184.2 | 137.0 | 146.3 (-5.0) | 13.17 |
| 2025.02 | 184.2 | 179.7 | 155.7 | 139.9 (-6.4) | 14.42 |
| 2025.03 | 163.7 | 162.1 | 134.2 | 136.0 (-3.9) | 15.96 |
| 2025.04 | 162.5 | 163.6 | 140.6 | (133.7 projected, -2.3) | 17.62 |
| 2025.05 | 135.3 | 138.3 | 79.2 | (130.1 projected, -3.6) | 17.26 |
| 2025.06 | 131.3 | 135.4 | 116.3 | (126.3 projected, -3.8) | 21.43 |
| 2025.07 | 137.8 | 142.3 | 125.6 | (123.0 projected, -3.3) | 11.80 |
| 2025.08 | 154.9 | 158.7 | 133.6 | (119.4 projected, -3.6) | 9.97 |
| 2025.09 | 154.4 | 156.0 | 129.6 | (115.5 projected, -3.9) | 14.1 |
| 2025.10 | (1) | (2A) / (2B) / 148.4 (2C) | (111.5 projected, -4.0) | () | |
| 2025.11 | (109.3 projected, -2.2) | ||||
| 2025.12 | (107.6 projected, -1.7) | ||||
| 2026.01 | (103.5 projected, -4.1) | ||||
| 2026.02 | (99.4 projected, -4.1) | ||||
| 2026.03 | (95.0 projected, -4.4) | ||||
1) Running average based on the daily 20:00 UTC observed solar flux value
at 2800 MHz and any corrections applied to that measurement.
2A) Current impact on the monthly sunspot number based on the Boulder
(NOAA/SWPC) sunspot number (accumulated daily sunspots / month days).
2B) Boulder SN current month average to date.
2C) STAR SDO 1K Wolf number 27 day average.
3) Running average based on the quicklook and definitive Potsdam WDC ap
indices. Values in red
are based on the definitive international
GFZ Potsdam WDC ap
indices.
4) Source: WDC-SILSO, Royal Observatory
Of Belgium, Brussels
Sunspot activity has been on a decreasing trend since September
2024 (using the average solar flux over 3 solar rotations as a proxy).
Compared to the peak of SC25 solar flux has been at a low level in both May
and June 2025. Taking a closer look at the 81 day (3 solar rotations)
average solar flux proxy, its peak was in early September 2024 and had on
May 12 decreased to less than half of the solar cycle flux range.
Subtracting the 81 day average of approximately 69 at solar cycle minimum
from all measurements, the SC25 range is 0 - 158.3.
All 365 day smoothed sunspot numbers peaked on October 11-12, 2024,
very likely making this the peak of SC25 (365 day smoothed peaks: STAR 1K: 236.1, STAR 2K: 364.3, NOAA SN: 156.0, ISN: 163.9). The 365d
smoothed solar flux peaked on October 13, 2024, just 1.7% below the SC23
peak, and 62.6% above the SC24 peak.
--------------------------------------------------------------------------------------
This report has been prepared by Jan Alvestad. It is based on the analysis of data from whichever sources are available at the time the report is prepared. All time references are to Universal Time. Comments and suggestions are always welcome.
SDO images are courtesy of NASA/SDO and the AIA, EVE, and HMI science teams.
