The geomagnetic field was at unsettled to minor storm levels on September 29. A disturbance with an unknown source was in progress most of the day. The phi angle was in a negative sector until 16h UT at ACE, then swung into a positive sector until 01h on September 30. Bz was at -16 nT at 04h UT on September and the geomagnetic field is currently at major storm levels. Solar wind speed at SOHO ranged between 373 and 432 km/sec, averaging 401 km/sec (-21 km/sec compared to the previous day). The high latitude magnetometer at Andenes recorded unsettled to minor 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
186.4 -
decreasing 1.0
over the previous solar rotation.
The 365 day average solar flux at 1
AU was 168.93 (183 days ago). The 81 day average solar flux at 1 AU was
155.1 (41 days ago, this is 54.4% 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 28 (STAR Ap - based on the average of three hour interval ap indices: 27.5). Three hour interval K indices: 22344554 (planetary), 23344442 (Boulder), 43344555 (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 14 active regions using 2K resolution (SN: 347) and in 13 active regions using 1K resolution (SN: 240) SDO/HMI images.
AR 14226 [S10W48] decayed slowly and quietly.
AR 14228 [N05W37] decayed slowly and quietly.
AR 14230 [S10W26] developed further and gained a magnetic delta
configuration. A major flare is possible. C1 flares: C1.9 @ 17:44, C1.9 @
18:13 UT
AR 14232 [N03E35] gained spots and area. The magnetic delta
configuration disappeared. There's significant polarity intermixing. Spots
to the north of the main penumbra area being considered for a split. M
flares are still likely.
AR 14233 [N18E37] decayed significantly and simplified. Flare
activity decreased a lot compared to the previous days.
AR 14234 [S27W05] was quiet and stable.
AR 14235 [N27E37] decayed and was mostly quiet.
AR 14236 [N09E27] gained area and spots while losing the magnetic
delta configuration. The level of polarity intermixing decreased to minor. M
flares are likely. C1 flares: C1.7 @ 00:22, C1.8 @ 00:37, C1.9 @ 06:43 UT
New AR 14237 [N15W07] emerged on September 28 and was numbered by
SWPC the next day.
Spotted regions not observed (or interpreted
differently) by SWPC/USAF:
S11463 [S16W53] decayed slowly and produced a few C flares.
S11476 [S14W28] developed further. This is probably AR 14238,
however, the match with imprecise SWPC data is not very good.
New AR S11479 [N09W05] emerged with a few spots.
New AR S11480 [N17E81] rotated into view with small and tiny spots.
New AR S11481 [S16E14] emerged with tiny spots.
C2+ flares
| Magnitude | Peak time (UT) | Location | Source | Recorded by | Comment |
| M3.6 | 01:45 | 14232 | GOES18 | ||
| M1.3 | 01:51 | 14232 | GOES18 | different flare center from above M3.6 flare | |
| C2.1 | 02:45 | 14230 | GOES18 | ||
| C2.9 | 03:21 | 14230 | GOES18 | ||
| C2.9 | 03:32 | 14236 | GOES18 | ||
| C4.4 | 03:58 | S11463 | GOES18 | ||
| C4.0 | 04:08 | 14230 | GOES18 | ||
| C6.5 | 04:14 | 14232 | GOES18 | ||
| C4.9 | 04:36 | 14236 | GOES18 | ||
| C2.7 | 05:25 | 14236 | GOES18 | ||
| C2.5 | 07:05 | 14236 | GOES18 | ||
| C3.9 | 07:22 | 14233 | GOES18 | ||
| C3.2 | 07:38 | 14236 | GOES18 | ||
| C3.6 | 08:02 | 14236 | GOES18 | ||
| C2.8 | 08:40 | 14233 | GOES19 | ||
| C2.4 | 08:59 | 14230 | GOES19 | ||
| C3.0 | 09:14 | 14233 | GOES19 | ||
| C2.9 | 10:04 | 14233 | GOES19 | ||
| C3.0 | 10:18 | 14232 | GOES19 | ||
| C2.6 | 11:03 | 14236 | GOES19 | ||
| M1.0/2N | 11:15 | 14232 | GOES18 | ||
| M1.1 | 11:38 | 14236 | GOES18 | ||
| M1.1 | 11:43 | 14232 | GOES18 | ||
| M1.0 | 11:59 | 14233 | GOES18 | ||
| C8.4/1N | 12:18 | S12W17 | 14230 | GOES18 | |
| C2.4 | 13:40 | 14236 | GOES18 | ||
| C4.4/1N | 14:25 | 14232 | GOES18 | ||
| C3.4 | 14:42 | 14232 | GOES18 | ||
| C2.3 | 15:00 | 14236 | GOES18 | ||
| C2.5 | 15:55 | S11463 | GOES18 | simultaneous flare in AR 14226 | |
| C2.2 | 16:28 | 14236 | GOES18 | ||
| C3.3 | 16:38 | 14236 | GOES18 | ||
| C2.5 | 16:50 | 14232 | GOES18 | ||
| C3.0 | 17:04 | 14236 | GOES18 | ||
| C3.0 | 17:17 | 14236 | GOES18 | ||
| C2.3 | 19:30 | 14236 | GOES18 | ||
| C2.4 | 19:42 | S11476 | GOES18 | ||
| C2.5 | 19:56 | 14230 | GOES18 | ||
| C2.4 | 20:01 | 14230 | GOES18 | ||
| C3.9 | 20:11 | 14236 | GOES18 | ||
| C3.5 | 20:32 | 14232 | GOES18 | ||
| C2.5 | 20:58 | 14236 | GOES18 | ||
| C2.5 | 21:19 | 14230 | GOES18 | ||
| C2.4 | 21:35 | 14236 | GOES18 | ||
| C2.5 | 22:06 | 14236 | GOES18 | ||
| C2.7 | 22:31 | 14236 | GOES18 | ||
| C3.8 | 22:50 | N06E34 | 14232 | GOES18 | |
| C2.8 | 23:10 | 14230 | GOES18 | ||
| C2.9 | 23:25 | 14236 | GOES18 |
September 27-29: No obviously Earth directed CMEs.
[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 small recurrent southern hemisphere negative polarity coronal hole (CH1318) rotated across the central meridian on September 24. A small northern hemisphere negative polarity coronal hole (CH1319) was Earth facing on September 25. A trans equatorial positive polarity coronal hole (CH1320) will rotate across the central meridian on September 29-30. 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 severe storm levels on September 30 and quiet to unsettled on October 1. October 2-6 could see quiet to minor storm levels 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 | ||||||||||
| 14225 | 2025.09.16 2025.09.16 |
1 | N08W91 | 0120 | HSX |
 |
was AR S11442 location: N10W91 rotated out of view |
||||
| 14227 | 2025.09.19 2025.09.20 |
3 | S17W56 | 0010 | BXO |
 |
was AR S11448 location: S20W48 spotless SWPC location is way off. |
||||
| 14226 | 2025.09.19 2025.09.20 |
3 | 6 | 4 | S11W48 | 0070 | HSX | CAO |
 |
 |
was AR S11449 area: 0170 location: S10W48 |
| 14228 | 2025.09.20 2025.09.21 |
6 | 2 | N05W41 | 0010 | BXO |
 |
 |
was AR S11453 location: N05W37 |
||
| S11455 | 2025.09.21 | N30W44 | |||||||||
| 14230 | 2025.09.22 2025.09.23 |
16 | 47 | 25 | S11W23 | 0100 | DAO | DAC |
 |
 |
beta-gamma-delta was AR S11456 location: S10W26 area: 0400 |
| S11458 | 2025.09.22 | S22W39 | |||||||||
| S11460 | 2025.09.24 | S17W26 |
 |
||||||||
| 14233 | 2025.09.25 2025.09.27 |
8 | 28 | 13 | N17E34 | 0060 | DAO | DRI |
 |
 |
beta-gamma was AR S11461 area: 0150 location: N18E37 |
| 14232 | 2025.09.26 2025.09.26 |
3 | 30 | 16 | N05E35 | 0250 | DHO | DKI |
 |
 |
beta-gamma was AR S11462 area: 0410 location: N03E35 |
| S11463 | 2025.09.26 | 4 | 3 | S16W53 | 0020 | DRO |
 |
 |
SWPC has moved AR 14227 to this AR |
||
| S11464 | 2025.09.26 | N17W48 | |||||||||
| S11465 | 2025.09.26 | S08E08 | |||||||||
| S11466 | 2025.09.26 | S30W14 | |||||||||
| 14234 | 2025.09.27 2025.09.27 |
4 | 1 | S23W09 | 0008 | AXX |
 |
 |
was AR S11467 location: S27W05 |
||
| 14235 | 2025.09.27 2025.09.27 |
3 | 6 | 2 | N28E38 | 0025 | CAO | CAO |
 |
 |
area: 0070 location: N27E37 |
| 14236 | 2025.09.27 2025.09.28 |
12 | 45 | 28 | N11E27 | 0080 | DAI | DAC |
 |
 |
beta-gamma was AR S11469 area: 0460 location: N09E27 |
| S11470 | 2025.09.27 | N07E10 |
 |
||||||||
| S11471 | 2025.09.27 | S14W32 |
 |
||||||||
| S11472 | 2025.09.27 | S26W30 | |||||||||
| S11473 | 2025.09.27 | N02W08 | |||||||||
| 14237 | 2025.09.28 2025.09.29 |
3 | 9 | 5 | N16W05 | 0010 | BXO | CRO |
 |
 |
was AR S11474 location: N15W07 area: 0030 |
| S11476 | 2025.09.28 | 15 | 9 | S14W28 | 0020 | DAO |
 |
 |
this could be AR 14238, see below | ||
| S11477 | 2025.09.28 | S03W05 |
 |
||||||||
| 14238 | 2025.09.29 | 6 | S13W26 | 0010 | BXO | this could be the same AR as AR S11476, however SWPC/USAF data don't match well | |||||
| 14239 | 2025.09.29 | 2 | S09W27 | 0045 | HAX | SWPC data could point to the leader spots of AR 14230, however, there is currently no justification for a split. This appears to be a major misinterpretation | |||||
| S11479 | 2025.09.29 | 3 | 1 | N09W05 | 0015 | CRO |
 |
||||
| S11480 | 2025.09.29 | 2 | 1 | N17E81 | 0020 | HRX |
 |
||||
| S11481 | 2025.09.29 | 2 | S16E14 | 0002 | BXO |
 |
|||||
| Total spot count: | 60 | 207 | 110 | ||||||||
| Sunspot number: | 170 | 347 | 240 | (total spot count + 10 * number of spotted regions) | |||||||
| Weighted SN: | 105 | 257 | 160 | (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): | 187 | 191 | 192 | ||||||||
| Month | Average solar flux | International sunspot number (WDC-SILSO) |
Smoothed sunspot number (4) | Average
ap (3) |
|
|---|---|---|---|---|---|
| Measured | 1 AU | ||||
| 2024.03 | 154.4 | 152.9 | 103.7 | 141.4 (+4.5) | 11.03 |
| 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 | (135.6 projected, -4.3) | 15.96 |
| 2025.04 | 162.5 | 163.6 | 140.6 | (132.5 projected, -3.1) | 17.62 |
| 2025.05 | 135.3 | 138.3 | 79.2 | (127.6 projected, -4.9) | 17.26 |
| 2025.06 | 131.3 | 135.4 | 116.3 | (122.8 projected, -4.8) | 21.43 |
| 2025.07 | 137.8 | 142.3 | 125.6 | (118.9 projected, -3.9) | 11.80 |
| 2025.08 | 154.9 | 158.7 | 133.6 | (114.1 projected, -4.8) | 9.97 |
| 2025.09 | 153.3 (1) | 122.0 (2A) / 126.2 (2B) / 148.8 (2C) ISN average to date: 134. At this level the SSN for March 2025 will become 136.3 |
(109.7 projected, -4.4) | (12.0) | |
| 2025.10 | (105.8 projected, -3.9) | ||||
| 2025.11 | (103.6 projected, -2.2) | ||||
| 2025.12 | (101.9 projected, -1.7) | ||||
| 2026.01 | (97.8 projected, -4.1) | ||||
| 2026.02 | (93.7 projected, -4.1) | ||||
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.
