The geomagnetic field was at quiet to unsettled levels on October 21, weakly under the influence of effects associated with CH1323. Solar wind speed at SOHO ranged between 471 and 604 km/sec, averaging 511 km/sec (-43 km/sec compared to the previous day). The high latitude magnetometer at Andenes recorded quiet to active levels. The above 10 MeV proton flux was at background levels all day. Early on October 22 proton fluxes increased slowly due to the huge backsided event around 20h UT on Oct.21. At 04:00 UT the above 10 MeV flux was at 1.0 pfu.
Solar flux density measured at 20h UT on 2.8 GHz was
132.9 -
decreasing 44.3
over the previous solar rotation.
The 365 day average solar flux at 1 AU was 164.86 (183 days ago). The 81 day
average solar flux at 1 AU was 154.5 (41 days ago, this is 54.0% 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 8 (STAR Ap - based on the average of three hour interval ap indices: 8.5). Three hour interval K indices: 33201223 (planetary), 33202312 (Boulder), 43310244 (Andenes).
The background x-ray flux is at the class B9 level (GOES 19).
At the time of counting spots (see image time), spots were observed in 12 active regions using 2K resolution (SN: 194) and in 11 active regions using 1K resolution (SN: 143) SDO/HMI images.
AR 14252 [S13W53] was quiet and stable.
AR 14254 [N10W19] was quiet and stable.
AR 14255 [S09W25] reemerged with tiny spots.
AR 14256 [S16W00] decayed slowly and was mostly quiet. C1 flares:
C1.0 @ 12:03 UT
AR 14257 [S09E21] was quiet and stable.
AR 14259 [S20E22] was quiet and stable.
AR 14260 [S11E38] decayed slowly and quietly.
AR 14261 [S06E53] was mostly quiet and stable.
C1 flares: C1.0 @ 19:20, C1.1 @ 20:06 UT
AR 14262 [S13E21] gained a few spots and was mostly quiet. The region
was the source of a C4.4 flare at 00:34 UT on October 22. This event may
have triggered an LDE in AR 14259 starting at 01:06 UT and may have been
associated with a CME. C1 flares: C1.5 @ 00:55 UT
New AR 14263 [N06W13] reemerged on October 20 with several spots,
developed further early on October 21, then decayed slowly as the spot group
was numbered by SWPC.
New AR 14264 [N08E54] rotated into view on October 19 and was noticed
by SWPC 2 days later as the region began to decay slowly.
Spotted regions not observed (or interpreted
differently) by SWPC/USAF:
New AR S11547 [N01E36] emerged with tiny spots.
AR 14250 behind the northwest limb was the source of
C1 flares: C1.7 @ 01:24, C1.2 @ 02:31, C1.3 @ 06:00, C1.0 @ 08:03, C1.1 @
11:13 UT.
Active regions behind the northeast limb were the sources of C1 flares: C1.5
@ 03:34, C1.2 @ 05:10, C1.5 @ 23:47 UT
C2+ flares
| Magnitude | Peak time (UT) | Location | Source | Recorded by | Comment |
| C3.7 | 06:49 | behind northeast limb | GOES18 |
October 19-20: 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 recurrent positive polarity southern hemisphere coronal hole (CH1324) will likely become Earth facing on October 26-27.
The geomagnetic field is expected to be at mostly quiet levels on October 22-24.
| 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 | ||||||||||
| 14251 | 2025.10.10 2025.10.12 |
N19W85 |
was AR S11514 location: N19W89 |
||||||||
| 14252 | 2025.10.11 2025.10.12 |
3 | 3 | 2 | S10W55 | 0110 | CSO | CSO |
 |
 |
was AR S11517 area: 0170 location: S13W53 |
| 14254 | 2025.10.13 2025.10.14 |
1 | 5 | 2 | N10W21 | 0060 | HSX | CSO |
 |
 |
was AR S11523 area: 0110 location: N10W19 |
| S11524 | 2025.10.13 | S04W47 | |||||||||
| 14255 | 2025.10.14 2025.10.16 |
2 | 2 | S08W30 | 0004 | AXX |
 |
was AR S11526 location: S09W25 |
|||
| 14256 | 2025.10.15 2025.10.16 |
1 | 10 | 4 | S16W01 | 0010 | AXX | BXO |
 |
 |
was AR S11529 area: 0020 location: S16W00 |
| S11530 | 2025.10.16 | N22W16 | |||||||||
| S11531 | 2025.10.16 | N15W37 | |||||||||
| 14258 | 2025.10.16 2025.10.18 |
S14W83 |
 |
was AR S11532 location: S15W85 |
|||||||
| 14263 | 2025.10.17 2025.10.21 |
3 | 9 | 4 | N05W12 | 0010 | BXO | CRO |
 |
 |
was AR S11533 area: 0030 location: N06W13 |
| 14257 | 2025.10.17 | 2 | 3 | 1 | S10E23 | 0070 | CSO | HSX |
 |
 |
was AR S11534 area: 0180 location: S09E21 |
| S11535 | 2025.10.17 | S20W51 | |||||||||
| 14262 | 2025.10.17 2025.10.20 |
2 | 14 | 7 | S12E22 | 0150 | HSX | DAO |
 |
 |
was AR S11536 area: 0230 location: S13E21 |
| S11537 | 2025.10.17 | N06W23 | |||||||||
| S11538 | 2025.10.17 | N14E15 |
 |
||||||||
| 14259 | 2025.10.18 2025.10.19 |
1 | 11 | 4 | S20E22 | 0010 | AXX | BXO |
 |
 |
was AR S11539 area: 0025 |
| 14260 | 2025.10.18 2025.10.19 |
5 | S10E33 | 0010 | BXO |
 |
 |
was AR S11540 location: S11E38 |
|||
| S11541 | 2025.10.18 | N48W28 | |||||||||
| 14261 | 2025.10.19 2025.10.20 |
3 | 5 | 4 | S06E54 | 0050 | CSO | CSO |
 |
 |
was AR S11543 area: 0100 location: S06E53 |
| 14264 | 2025.10.19 2025.10.21 |
1 | 4 | 2 | N07E55 | 0010 | AXX | HRX |
 |
 |
was AR S11544 area: 0015 |
| S11545 | 2025.10.19 | S22W30 | |||||||||
| S11546 | 2025.10.20 | N11E20 |
 |
||||||||
| S11547 | 2025.10.21 | 3 | 1 | N01E36 | 0005 | BXO |
 |
||||
| Total spot count: | 17 | 74 | 33 | ||||||||
| Sunspot number: | 107 | 194 | 143 | (total spot count + 10 * number of spotted regions) | |||||||
| Weighted SN: | 42 | 105 | 64 | (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): | 118 | 107 | 114 | ||||||||
| 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 | 146.6 (1) | 79.4 (2A) / 117.2 (2B) / 159.5 (2C) ISN month to date average: 125 At this level the April 2025 SSN would become 133.9 |
(111.5 projected, -4.0) | (17.0) | |
| 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.
