The geomagnetic field was at inactive to very quiet levels on December 8. Solar wind speed at SOHO ranged between 295 and 494 km/sec, averaging 363 km/sec (-167 km/sec compared to the previous day). The high latitude magnetometer at Andenes was at inactive to quiet levels. The above 10 MeV proton flux was just above background levels all day.
Solar flux density measured at 20h UT on 2.8 GHz was 186.2 - increasing 18.2 over the previous solar rotation.
The 365 day average solar flux at 1 AU was 157.69 (183 days ago). The 81 day average solar flux at 1 AU was 148.9 (41 days ago, this is 50.5% 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 1 (STAR Ap - based on the average of three hour interval ap indices: 0.6). Three hour interval K indices: 00000010 (planetary), 00001121 (Boulder), 00000022 (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 12 active regions using 2K resolution (SN: 350) and in 11 active regions using 1K resolution (SN: 225) SDO/HMI images.
AR 14294 [S16W40] developed significantly in
the intermediate spot section gaining several magnetic delta configurations.
Major flares are possible. An interesting development is that the distance
between this AR and AR 14296 has been decreasing over the last few days,
there is an increasing chance of interaction between the two ARs. C1 flares:
C1.8 @ 09:36, C1.8 @ 10:17, C1.9 @ 10:46, C1.7 @ 10:59, C1.5 @ 11:33, C1.6 @
11:53, C1.9 @ 17:22, C1.9 @ 17:25, C1.8 @ 17:33, C1.6 @ 17:53, C1.9 @ 20:23
UT
AR 14295 [N03W34] decayed further and could soon become spotless.
AR 14296 [S14W31] was mostly quiet. The leading spot section is
increasingly coming under the influence of the trailing polarity field of AR
14294.
AR 14298 [S16W62] decayed slowly having produced several C, M and X
flares during the day. C1 flares: C1.9 @ 02:14 UT
AR 14299 [N22W21] decayed further barely retaining mature penumbra in
the trailing spot section. There is a decreasing chance of major flare
activity.
AR 14300 [N08W13] decayed slowly and quietly.
AR 14303 [S26E37] was mostly quiet and stable.
New AR 14304 [N25W08] emerged on December 6 and was noticed by SWPC 2
days later. The region has a small magnetic delta configuration in the
central spot section, however, no spots have mature penumbra yet. Minor M
class flares are possible.
Spotted regions not observed (or interpreted
differently) by SWPC/USAF:
AR S11661 [N15W33] was quiet and stable.
AR S11663 [S18W08] was quiet and stable.
AR S11668 [S26E17] developed slowly and
quietly. C1 flares: C1.9 @ 20:30 UT
New AR S11671 [S24E47] emerged with several spots. C1 flares: C1.8 @
16:54, C1.9 @ 18:35 UT
C2+ flares
| Magnitude | Peak time (UT) | Location | Source | Recorded by | Comment |
| M2.0/1N | 00:36 | S15W30 | 14294 | GOES18 | |
| C2.7 | 01:44 | S15W38 | 14294 | GOES18 | |
| C2.4 | 02:23 | 14294 | GOES18 | ||
| C2.0 | 02:32 | 14294 | GOES18 | ||
| C2.1 | 02:36 | 14299 | GOES18 | ||
| C3.6 | 02:57 | 14296 | GOES18 | ||
| C2.5 | 03:29 | 14296 | GOES18 | ||
| C4.1 | 03:46 | S15W39 | 14294 | GOES18 | simultaneous flare in AR 14304 |
| C2.2 | 04:05 | 14294 | GOES18 | ||
| C6.2 | 04:27 | S15W39 | 14294 | GOES18 | |
| X1.1/2B | 05:01 | S14W52 | 14298 | GOES18 | moderate type II radio sweep |
| C3.5 | 05:26 | N26E02 | 14304 | GOES18 | |
| C2.2 | 06:00 | 14299 | GOES18 | ||
| C2.0 | 06:38 | 14294 | GOES18 | ||
| M1.8/1N | 06:54 | N22W09 | 14299 | GOES18 | |
| C3.8 | 07:35 | 14294 | GOES18 | ||
| C3.5 | 07:50 | 14294 | GOES18 | ||
| C2.6 | 08:21 | 14304 | GOES18 | ||
| C8.0/1F | 08:57 | 14294 | GOES18 | ||
| C7.1 | 09:02 | S13W58 | 14298 | GOES18 | |
| C3.2 | 09:14 | 14294 | GOES18 | ||
| C2.8 | 09:21 | 14294 | GOES18 | ||
| C5.2 | 12:28 | S15W41 | 14294 | GOES18 | |
| M1.0 | 13:05 | S16W41 | 14294 | GOES18 | |
| C4.8 | 14:06 | 14299 | GOES18 | ||
| C3.3 | 14:30 | S11671 | GOES18 | ||
| C3.7 | 15:05 | S16W42 | 14294 | GOES18 | |
| C2.6 | 15:24 | S11671 | GOES18 | ||
| C2.1 | 15:50 | 14296 | GOES18 | ||
| C4.7 | 15:54 | 14294 | GOES18 | ||
| C2.1 | 16:22 | 14304 | GOES18 | ||
| C2.0 | 18:04 | 14294 | GOES18 | ||
| C2.4 | 18:11 | 14304 | GOES18 | ||
| C2.2 | 18:17 | 14294 | GOES18 | ||
| C2.0 | 19:45 | 14294 | GOES18 | ||
| C2.4 | 20:04 | 14294 | GOES18 | ||
| C3.7 | 21:06 | 14294 | GOES18 | ||
| M3.1 | 21:17 | 14304 | GOES18 | ||
| M2.6 | 21:21 | 14294 | GOES18 | ||
| C2.4 | 22:01 | 14294 | GOES18 | ||
| M1.2/1F | 22:28 | 14299 | GOES18 | simultaneous flare in AR 14294 | |
| C2.3 | 23:32 | 14294 | GOES18 | ||
| C2.6 | 23:59 | 14298 | GOES18 |
December 6: An asymmetric full halo CME was observed late in the day after the M8
flare in AR 14299. The CME could reach Earth sometime between noon on December 8
and noon on December 9 and cause
active to severe storm levels.
December 7: No obviously Earth directed CMEs were observed in
available coronagraph imagery.
December 8: A partial halo CME became visible in LASCO C2 imagery at
23:00 with most of the ejecta observed off the northwest limb. The most
likely source is the M1.2 flare in AR 14299 peaking at 22:28 UT. There is a
chance that CME components could reach Earth on December 11.
[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 northern hemisphere negative polarity coronal hole (CH1334) will likely become Earth facing on December 10-12.
The geomagnetic field is expected to be at quiet levels on December 9 until the arrival of the December 6 CME. Unsettled to major storm levels are likely from then until December 10. Another CME could reach Earth on December 11-12 and cause unsettled to minor storm conditions. Effects from CH1334 could cause quiet to minor storm levels on December 13-15.
| 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 | ||||||||||
| 14294 | 2025.11.28 2025.11.28 |
32 | 71 | 41 | S16W42 | 0800 | FKC | EKC |
 |
 |
beta-gamma-delta was AR S11642 location: S16W40 area: 0980 |
| 14296 | 2025.11.29 2025.11.30 |
14 | 39 | 23 | S14W30 | 0500 | EKC | EKI |
 |
 |
beta-gamma was AR S11647 area: 0600 location: S14W31 |
| 14295 | 2025.11.29 2025.11.30 |
1 | 6 | 2 | N06W41 | 0010 | AXX | BXO |
 |
 |
was AR S11648 location: N03W34 |
| 14299 | 2025.11.30 2025.12.01 |
7 | 30 | 17 | N22W25 | 0130 | DAI | DAC |
 |
 |
beta-delta was AR S11649 location: N22W21 |
| 14298 | 2025.12.01 | 5 | 3 | 3 | S16W64 | 0060 | CSO | CAO |
 |
 |
area: 0180 location: S16W62 |
| 14300 | 2025.12.01 2025.12.02 |
1 | 13 | 3 | N08W17 | 0010 | AXX | BXO |
 |
 |
was AR S11654 area: 0015 location: N08W13 |
| S11660 | 2025.12.03 | N17W48 | |||||||||
| S11661 | 2025.12.04 | 10 | 3 | N15W33 | 0015 | BXO |
 |
 |
|||
| S11662 | 2025.12.05 | N05E03 | |||||||||
| S11663 | 2025.12.05 | 12 | S18W08 | 0020 | BXO |
 |
 |
||||
| 14304 | 2025.12.06 2025.12.08 |
3 | 25 | 11 | N26W08 | 0020 | CRO | DRI |
 |
 |
beta-delta was AR S11664 area: 0090 location: N25W08 |
| 14303 | 2025.12.06 2025.12.07 |
3 | 7 | 3 | S27E38 | 0020 | CSO | CAO |
 |
 |
was AR S11665 area: 0030 location: S26E37 |
| S11668 | 2025.12.07 | 7 | 4 | S26E17 | 0020 | DRO |
 |
 |
|||
| S11669 | 2025.12.07 | S05W17 |
 |
||||||||
| S11670 | 2025.12.07 | N01E13 |
 |
||||||||
| S11671 | 2025.12.08 | 7 | 5 | S24E47 | 0030 | DRI |
 |
||||
| Total spot count: | 66 | 230 | 115 | ||||||||
| Sunspot number: | 146 | 350 | 225 | (total spot count + 10 * number of spotted regions) | |||||||
| Weighted SN: | 104 | 274 | 159 | (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): | 161 | 193 | 180 | ||||||||
| Month | Average solar flux | International sunspot number (WDC-SILSO) |
Smoothed sunspot number (4) | Average
ap (3) |
|
|---|---|---|---|---|---|
| Measured | 1 AU | ||||
| 2024.05 | 187.7 | 191.9 | 172.1 | 149.1 (+4.6) | 23.56 (SC25 peak) |
| 2024.08 | 246.1 (SC25 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 | 157.2 (-3.7) | 9.33 |
| 2024.12 | 197.3 | 191.2 | 154.6 | 151.2 (-6.0) | 8.42 |
| 2025.01 | 190.3 | 184.2 | 137.0 | 146.2 (-5.0) | 13.17 |
| 2025.02 | 184.2 | 179.7 | 155.7 | 139.8 (-6.4) | 14.42 |
| 2025.03 | 163.7 | 162.1 | 134.2 | 135.9 (-3.9) | 15.96 |
| 2025.04 | 162.5 | 163.6 | 141.4 | 133.3 (-2.6) | 17.62 |
| 2025.05 | 135.3 | 138.3 | 78.5 | 128.5 (-4.8) | 17.26 |
| 2025.06 | 131.3 | 135.4 | 114.6 | (124.4 projected, -4.1) | 21.43 |
| 2025.07 | 137.8 | 142.3 | 125.6 | (121.7 projected, -2.7) | 11.80 |
| 2025.08 | 154.9 | 158.7 | 133.5 | (118.0 projected, -3.7) | 9.97 |
| 2025.09 | 154.4 | 156.0 | 129.8 | (114.1 projected, -3.9) | 14.02 |
| 2025.10 | 139.5 | 138.6 | 114.6 | (110.1 projected, -4.0) | 15.64 |
| 2025.11 | 140.3 | 137.3 | 91.7 | (107.9 projected, -2.2) | 21.01 |
| 2025.12 | 201.7 (1) | 41.5 (2A) / 160.6 (2B) / 136.0 (2C) | (106.3 projected, -1.6) | (14.7) | |
| 2026.01 | (102.3 projected, -4.0) | ||||
| 2026.02 | (98.2 projected, -4.1) | ||||
| 2026.03 | (93.8 projected, -4.4) | ||||
| 2026.04 | (90.1 projected, -3.7) | ||||
| 2026.05 | (88.9 projected, -1.2) | ||||
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 was on a decreasing trend from September
2024 until mid August 2025 (using the average solar flux over 3 solar rotations as a proxy).
Then a strong surge in activity saw solar flux peak in late August 2025 just
below the largest peaks seen in 2024. A slow decrease in activity from the
August level has been observed in September and October 2025.
All 365 day smoothed sunspot numbers reached a maximum on October 11-12, 2024.
This became the peak of SC25 (365 day smoothed peaks: STAR 1K: 236.1, STAR 2K: 364.3, NOAA SN: 156.0, ISN: 163.9),
while 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.
