The geomagnetic field was at quiet levels on October 23. Solar wind speed at SOHO ranged between 395 and 533 km/sec, averaging 448 km/sec (+6 km/sec compared to the previous day). A disturbance related to CH1325 is in progress early on October 24. The high latitude magnetometer at Andenes recorded quiet to active levels. The above 10 MeV proton flux was at 0.3 pfu at the end of the UT day, slowly decreasing towards background levels.
Solar flux density measured at 20h UT on 2.8 GHz was
129.9 -
decreasing 35.2
over the previous solar rotation.
The 365 day average solar flux at 1 AU was 164.59 (183 days ago). The 81 day
average solar flux at 1 AU was 154.0 (41 days ago, this is 53.7% 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 5 (STAR Ap - based on the average of three hour interval ap indices: 5.0). Three hour interval K indices: 21011122 (planetary), 11011322 (Boulder), 30001034 (Andenes).
The background x-ray flux is at the class B6 level (GOES 19).
At the time of counting spots (see image time), spots were observed in 15 active regions using 2K resolution (SN: 243) and in 14 active regions using 1K resolution (SN: 179) SDO/HMI images.
AR 14252 [S13W80] was mostly quiet and stable.
AR 14254 [N09W45] was quiet and stable.
AR 14257 [S09W05] was quiet and stable.
AR 14259 [S19W02] decayed slowly and quietly.
AR 14260 [S10E16] was quiet and stable.
AR 14261 [S06E27] was quiet and stable.
AR 14262 [S13W05] was mostly quiet and stable.
AR 14263 [N05W42] was quiet and stable.
AR 14264 [N08E28] was quiet and stable.
New AR 14266 [N15E42] emerged on October 22, developed further the
next day and was numbered by SWPC.
New AR 14267 [N01E71] rotated into view on October 22 and received
its NOAA number the next day. C1 flares: C1.5 @ 08:54, C1.0 @ 10:59, C1.2 @
14:43, C1.3 @ 14:50 UT
Spotted regions not observed (or interpreted
differently) by SWPC/USAF:
S11538 [N17W09] reemerged with tiny spots.
S11546 [N11E05] reemerged with tiny spots.
New AR S11552 [S02W02] emerged with tiny spots.
New AR S11553 [N01E06] emerged with tiny spots.
A C1.0 flare recorded at 04:43 UT had its origin at the southwest limb.
C2+ flares
| Magnitude | Peak time (UT) | Location | Source | Recorded by | Comment |
| C2.4 | 01:59 | 14267 | GOES18 | simultaneous flare at the southwest limb | |
| C2.0 | 04:24 | 14267 | GOES18 | ||
| C3.2 | 05:08 | 14267 | GOES18 | ||
| C2.1 | 15:06 | 14267 | GOES18 | ||
| C1.5+ | 15:21 (estimated from SDO/AIA imagery) | 14256 | GOES18 | magnitude unknown due to missing data, likely well above C2 based on flare intensity. Flare began at 15:16. |
October 22-23: No obviously Earth directed CMEs observed in available
coronagraph imagery.
October 21: A very impressive backsided full halo CME was observed in
LASCO imagery starting at 20:24 UT. This coincided with moderate type II and
IV radio sweeps, the type II radio sweep was very fast. The distribution of
the ejecta indicate that AR 14246 (several days behind the northwest limb)
was the source of the event.
[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 and narrow negative polarity trans equatorial coronal hole (CH1325) rotated across the central meridian on October 21. A recurrent positive polarity southern hemisphere coronal hole (CH1324) will likely become Earth facing on October 26-27. A recurrent positive polarity trans equatorial coronal hole (CH1326) will likely rotate across the central meridian on October 27.
The geomagnetic field is expected to be at quiet to unsettled levels on October 24 due to effects associated with CH1325 and quiet on October 25-26. Effects from CH1324 and CH1326 could cause unsettled to major storm conditions starting on October 27 or 28 lasting until October 31.
| 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 | ||||||||||
| 14252 | 2025.10.11 2025.10.12 |
1 | 1 | 1 | S13W81 | 0100 | HSX | HSX |
 |
 |
was AR S11517 area: 0150 location: S13W80 |
| 14254 | 2025.10.13 2025.10.14 |
1 | 2 | 2 | N10W47 | 0050 | HSX | HSX |
 |
 |
was AR S11523 area: 0090 location: N09W45 |
| 14255 | 2025.10.14 2025.10.16 |
S08W58 |
was AR S11526 location: S09W51 |
||||||||
| 14256 | 2025.10.15 2025.10.16 |
S16W28 |
 |
was AR S11529 location: S16W27 |
|||||||
| S11530 | 2025.10.16 | N22W42 | |||||||||
| 14263 | 2025.10.17 2025.10.21 |
4 | 3 | N06W42 | 0010 | AXX |
 |
 |
was AR S11533 location: N05W42 |
||
| 14257 | 2025.10.17 | 1 | 4 | 1 | S09W06 | 0060 | HSX | HSX |
 |
 |
was AR S11534 area: 0130 |
| 14262 | 2025.10.17 2025.10.20 |
3 | 16 | 8 | S12W07 | 0150 | HSX | DAO |
 |
 |
was AR S11536 area: 0210 location: S13W05 |
| S11537 | 2025.10.17 | N06W49 | |||||||||
| S11538 | 2025.10.17 | 3 | N17W09 | 0005 | BXO |
 |
|||||
| 14259 | 2025.10.18 2025.10.19 |
14 | 5 | S20W03 | 0020 | BXO |
 |
 |
was AR S11539 location: S19W02 |
||
| 14260 | 2025.10.18 2025.10.19 |
19 | 8 | S10E05 | 0040 | CRO |
 |
 |
was AR S11540 location: S12E16 |
||
| 14261 | 2025.10.19 2025.10.20 |
1 | 3 | 1 | S06E25 | 0030 | HSX | CSO |
 |
 |
was AR S11543 area: 0090 location: S06E27 |
| 14264 | 2025.10.19 2025.10.21 |
1 | 5 | 2 | N07E24 | 0010 | AXX | BXO |
 |
 |
was AR S11544 location: N08E28 |
| S11545 | 2025.10.19 | S22W56 | |||||||||
| S11546 | 2025.10.20 | 5 | 1 | N11E05 | 0010 | BXO |
 |
||||
| S11547 | 2025.10.21 | N01E10 | |||||||||
| 14265 | 2025.10.22 2025.10.22 |
N12W23 |
 |
was AR S11548 location: N11W21 |
|||||||
| 14267 | 2025.10.22 2025.10.23 |
1 | 3 | 1 | N01E67 | 0080 | HSX | HHX |
 |
 |
was AR S11549 are: 0300 location: N01E71 |
| 14266 | 2025.10.22 2025.10.23 |
3 | 7 | 4 | N15E43 | 0010 | BXO | DRO |
 |
 |
was AR S11550 area: 0040 location: N15E42 |
| S11552 | 2025.10.23 | 3 | 1 | S02W02 | 0006 | BXO |
 |
||||
| S11553 | 2025.10.23 | 4 | 1 | N01E06 | 0007 | BXO |
 |
||||
| Total spot count: | 12 | 93 | 39 | ||||||||
| Sunspot number: | 92 | 243 | 179 | (total spot count + 10 * number of spotted regions) | |||||||
| Weighted SN: | 42 | 134 | 80 | (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): | 101 | 137 | 143 | ||||||||
| 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 | 145.3 (1) | 86.1 (2A) / 116.1 (2B) / 155.4 (2C) ISN month to date average: 123 At this level the April 2025 SSN would become 133.7 |
(111.5 projected, -4.0) | (15.9) | |
| 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.
