The geomagnetic field was at quiet to active levels on October 4 under the decreasing influence of effects associated with CH1321. Solar wind speed at SOHO ranged between 546 and 748 km/sec, averaging 625 km/sec (-58 km/sec compared to the previous day). The high latitude magnetometer at Andenes recorded active to major 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
157.6 -
increasing 25.1
over the previous solar rotation.
The 365 day average solar flux at 1 AU was 167.64 (183 days ago). The 81 day
average solar flux at 1 AU was 157.3 (41 days ago, this is 55.8% 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 20 (STAR Ap - based on the average of three hour interval ap indices: 19.6). Three hour interval K indices: 34444432 (planetary), 34544422 (Boulder), 44444564 (Andenes).
The background x-ray flux is at the class C1 level (GOES 19).
At the time of counting spots (see image time), spots were observed in 17 active regions using 2K resolution (SN: 379) and in 15 active regions using 1K resolution (SN: 266) SDO/HMI images.
AR 14232 [N03W33] was mostly unchanged and
quiet. M flares are still possible. C1 flares: C1.9 @ 08:54 UT
AR 14233 [N19W27] decayed slowly and quietly.
AR 14235 [N26W28] decayed slowly and quietly.
AR 14236 [N10W40] was mostly unchanged and quiet. M flares are still
possible. C1 flares: C1.9 @ 15:46 UT
AR 14240 [N16E19] decayed slowly and quietly.
AR 14241 [N14E06] produced a few flares after noon.
AR 14242 [S11E14] developed slowly and produced a few C flares early
in the day. C1 flares: C1.8 @ 21.22 UT
AR 14243 [N18E42] was quiet and stable.
Spotted regions not observed (or interpreted
differently) by SWPC/USAF:
S11486 [N35W11] was quiet and stable.
S11491 [S11E03] was quiet and stable.
S11495 [N08W36] was quiet and stable.
S11497 [N29W02] was quiet and stable.
New AR S11499 [N08W76] emerged before noon with a tiny spot.
New AR S11500 [S20E78] rotated into view with small spots.
New AR S11501 [N08E08] emerged with tiny spots before noon,
then decayed slowly.
New AR S11502 [N15E32] emerged with a tiny
spot.
New AR S11503 [S00E35] emerged with tiny spots at the equator.
C2+ flares
| Magnitude | Peak time (UT) | Location | Source | Recorded by | Comment |
| C3.5 | 00:35 | 14242 | GOES18 | ||
| C2.7 | 00:54 | 14242 | GOES18 | ||
| C2.5 | 01:09 | 14242 | GOES18 | ||
| C5.5 | 01:42 | 14242 | GOES18 | ||
| C2.2 | 02:16 | 14242 | GOES18 | ||
| C4.7 | 03:22 | 14236 | GOES18 | ||
| C2.2 | 04:00 | 14242 | GOES18 | ||
| C2.3 | 04:09 | 14242 | GOES18 | ||
| C3.2 | 04:14 | 14242 | GOES18 | ||
| C2.1 | 04:32 | 14242 | GOES18 | ||
| C3.5 | 05:02 | 14232 | GOES18 | ||
| C2.3 | 05:16 | 14232 | GOES18 | ||
| C2.1 | 06:05 | 14230 | GOES18 | ||
| C2.6 | 06:17 | 14230 | GOES18 | ||
| C2.5 | 06:41 | 14242 | GOES18 | ||
| C2.1 | 10:31 | 14232 | GOES18 | ||
| C2.1 | 11:04 | 14242 | GOES18 | ||
| C2.2 | 11:48 | 14236 | GOES18 | ||
| C2.5 | 14:52 | 14230 | GOES18 | ||
| C3.5 | 17:52 | N16E12 | 14241 | GOES18 | |
| C2.7 | 18:45 | behind SW limb | 14230 | GOES18 | |
| C3.0 | 19:04 | behind SW limb | 14230 | GOES18 | |
| C2.1 | 22:05 | 14242 | GOES18 | ||
| C2.1 | 23:23 | 14241 | GOES18 |
October 2, 4: No obviously Earth directed CMEs.
October 3: A faint CME was observed after an M1.5 flare in AR 14236
at 05:22 UT. The CME could reach Earth on October 6.
[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 recurrent southern hemisphere positive polarity coronal hole (CH1321) was Earth facing on September 29 - October 4. A recurrent negative polarity trans equatorial coronal hole (CH1322) could rotate across the central meridian on October 7-8.
The geomagnetic field is expected to be at quiet to active levels on October 5-6 due to effects from CH1321. The October 3 CME could cause unsettled to minor storm conditions on October 6. Quiet to unsettled levels are likely on October 7.
| 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 | ||||||||||
| 14230 | 2025.09.22 2025.09.23 |
4 | S10W93 | 0200 | EAI |
 |
was AR S11456 rotated out of view SWPC spot data the same as the previous days |
||||
| 14233 | 2025.09.25 2025.09.27 |
2 | 10 | 4 | N19W31 | 0010 | HRX | BXO |
 |
 |
was AR S11461 area: 0020 location: N19W27 |
| 14232 | 2025.09.26 2025.09.26 |
18 | 40 | 26 | N04W34 | 0310 | DHI | DHI |
 |
 |
beta-gamma was AR S11462 area: 0390 location: N03W33 |
| S11465 | 2025.09.26 | S08W57 | |||||||||
| 14234 | 2025.09.27 2025.09.27 |
S23W80 |
was AR S11467 location: S27W71 |
||||||||
| 14235 | 2025.09.27 2025.09.27 |
1 | 2 | 2 | N27W33 | 0010 | AXX | AXX |
 |
 |
location: N26W28 |
| 14236 | 2025.09.27 2025.09.28 |
17 | 43 | 22 | N10W43 | 0320 | EKC | EKI |
 |
 |
was AR S11469 area: 0500 |
| S11470 | 2025.09.27 | N07W55 | |||||||||
| 14237 | 2025.09.28 2025.09.29 |
N16W76 |
was AR S11474 location: N15W72 |
||||||||
| 14240 | 2025.09.29 2025.09.30 |
8 | 2 | N17E11 | 0015 | BXO |
 |
 |
was AR S11480 location: N16E19 |
||
| S11481 | 2025.09.29 | S16W51 | |||||||||
| S11483 | 2025.09.30 | N06W58 | |||||||||
| 14241 | 2025.09.30 2025.10.01 |
8 | 25 | 16 | N14E05 | 0030 | DAI | DAI |
 |
 |
was AR S11484 area: 0140 location: N14E06 |
| S11485 | 2025.09.30 | N21W51 | |||||||||
| S11486 | 2025.09.30 | 3 | 1 | N35W11 | 0005 | BXO |
 |
 |
|||
| S11489 | 2025.10.01 | N03E22 | |||||||||
| S11490 | 2025.10.02 | N17E16 | |||||||||
| S11491 | 2025.10.02 | 9 | 1 | S11E03 | 0015 | BXO |
 |
 |
|||
| 14243 | 2025.10.02 2025.10.03 |
4 | 12 | 7 | N18E42 | 0010 | BXO | CRI |
 |
 |
was AR S11492 area: 0040 |
| S11493 | 2025.10.02 | N10W23 | |||||||||
| 14242 | 2025.10.02 2025.10.03 |
3 | 24 | 18 | S11E13 | 0080 | DAI | DAI |
 |
 |
was AR S11494 area: 0210 location: S11E14 SWPC spot count is a copy from the previous day and is obviously much too low |
| S11495 | 2025.10.03 | 20 | 11 | N08W36 | 0060 | DRI |
 |
 |
|||
| S11496 | 2025.10.03 | N09E31 |
 |
||||||||
| S11497 | 2025.10.03 | 3 | 1 | N29W02 | 0005 | AXX |
 |
 |
|||
| S11498 | 2025.10.03 | S19E20 |
 |
||||||||
| S11499 | 2025.10.04 | 1 | 1 | N08W76 | 0004 | AXX |
 |
||||
| S11500 | 2025.10.04 | 4 | 3 | S20E78 | 0040 | HRX |
 |
||||
| S11501 | 2025.10.04 | 2 | N08E08 | 0002 | BXO |
 |
|||||
| S11502 | 2025.10.04 | 1 | 1 | N15E32 | 0003 | AXX |
 |
||||
| S11503 | 2025.10.04 | 2 | S00E35 | 0003 | AXX |
 |
|||||
| Total spot count: | 57 | 209 | 116 | ||||||||
| Sunspot number: | 137 | 379 | 266 | (total spot count + 10 * number of spotted regions) | |||||||
| Weighted SN: | 95 | 248 | 155 | (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): | 151 | 208 | 213 | ||||||||
| 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 | 169.8 (1) | 19.6 (2A) / 152.3 (2B) / 152.7 (2C) | (111.5 projected, -4.0) | (35.4) | |
| 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.
