The geomagnetic field was at quiet to unsettled levels on January 1 under the influence of effects associated with CH1337. Solar wind speed at SOHO ranged between 440 and 552 km/sec, averaging 477 km/sec (+40 km/sec compared to the previous day). The above 10 MeV proton flux was at background levels all day.
Solar flux density measured at 20h UT on 2.8 GHz was 169.2 - decreasing 36.9 over the previous solar rotation.
The 365 day average solar flux at 1 AU was 154.07 (183 days ago). The 81 day average solar flux at 1 AU was 144.4 (41 days ago, this is 47.6% 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 11 (STAR Ap - based on the average of three hour interval ap indices: 11.4). Three hour interval K indices: 23323223 (planetary), 23233322 (Boulder), 44224343 (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 15 active regions using 2K resolution (SN: 321) and in 10 active regions using 1K resolution (SN: 173) SDO/HMI images.
AR 14319 [S08W69] reemerged with a tiny spot.
AR 14320 [N05W54] reemerged with tiny spots.
AR 14323 [S14W10] was mostly quiet and stable.
AR 14324 [N24W01] decayed slowly and still has a weak magnetic delta configuration.
C1 flares: C1.7 @ 01:03, C1.4 @ 09:57 UT
AR 14325 [S08W08] matured and continued to produce C flares. C1
flares: C1.6 @ 00:07, C1.8 @ 01:24, C1.7 @ 01:35, C1.9 @ 01:42, C1.6 @
03:14, C1.7 @ 05:06, C1.9 @ 07:05, C1.7 @ 08:06, C1.2 @ 12:35, C1.5 @ 14:45,
C1.6 @ 15:10, C1.7 @ 23:51 UT
AR 14329 [S14E11] was quiet and stable.
AR 14330 [S19E19] was quiet and stable.
AR 14331 [S25E24] decayed slowly and quietly.
AR 14332 [N15E18] decayed slowly and quietly.
Spotted regions not observed (or interpreted
differently) by SWPC/USAF:
AR S11734 [N03E10] was quiet and stable.
AR S11735 [S22E30] was quiet and stable.
New AR S11737 [N12W11] emerged with a tiny spot.
New AR S11738 [S09E16] emerged with tiny spots.
New AR S11739 [S11E18] emerged with tiny spots close to AR S11738.
New AR S11740 [S15E85] rotated partly into view with a mature spot.
AR 14317 at the northwest limb produced C1 flares: C1.7 @ 05:15, C1.2 @ 13:28, C1.7 @ 22:43 UT
C2+ flares
| Magnitude | Peak time (UT) | Location | Source | Recorded by | Comment |
| C9.6 | 02:25 | S09E06 | 14325 | GOES18 | |
| C2.4 | 04:03 | 14325 | GOES18 | ||
| C2.0 | 04:39 | 14325 | GOES18 | ||
| C2.0 | 05:37 | 14325 | GOES18 | ||
| C2.4 | 06:04 | 14325 | GOES18 | ||
| C4.4 | 06:22 | 14325 | GOES18 | ||
| C5.3 | 06:48 | S09E03 | 14325 | GOES18 | |
| C2.1 | 15:55 | 14324 | GOES18 | ||
| C6.2 | 17:59 | 14324 | GOES18 | LDE, CME | |
| C3.9 | 18:55 | 14317 | GOES18 | ||
| C2.7 | 21:50 | 14317 | GOES18 |
December 30: No obviously Earth directed CMEs were observed in
available coronagraph imagery.
December 31: A halo CME was observed after the M7 flare in AR 14324.
The CME could reach Earth on January 2-3.
January 1: A halo CME was observed after the C6.2 LDE in AR 14324
peaking at 17:59 UT. The CME could reach Earth on January 3-4.
[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 (CH1337) rotated across the central meridian on December 28-30.
The geomagnetic field is expected to be at quiet to minor storm levels on January 2-4 due to effects associated with CH1337 and several CMEs.
| 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 | ||||||||||
| 14317 | 2025.12.20 2025.12.20 |
1 | N11W90 | 0030 | HSX |
 |
was AR S11705 rotated out of view |
||||
| 14318 | 2025.12.21 2025.12.22 |
N05W87 |
was S11707 location: N07W76 |
||||||||
| 14319 | 2025.12.21 2025.12.22 |
1 | S12W68 | 0002 | AXX |
 |
was AR S11708 location: S08W69 |
||||
| 14320 | 2025.12.22 2025.12.23 |
2 | N06W59 | 0002 | AXX |
 |
was AR S11710 location: N05W54 |
||||
| S11713 | 2025.12.23 | S20W51 | |||||||||
| 14323 | 2025.12.25 2025.12.26 |
3 | 54 | 19 | S17W00 | 0010 | BXO | FRI |
 |
 |
was AR S11719 area: 0080 location: S14W10 |
| 14325 | 2025.12.26 2025.12.27 |
26 | 39 | 25 | S08W10 | 0330 | EKI | EKI |
 |
 |
beta-gamma was AR S11720 area: 0640 location: S08W08 |
| 14324 | 2025.12.26 2025.12.26 |
13 | 28 | 15 | N24W02 | 0170 | DAI | DAI |
 |
 |
beta-delta was AR S11721 area: 0280 location: N24W01 |
| S11722 | 2025.12.26 | N15W25 | |||||||||
| 14330 | 2025.12.27 2025.12.29 |
6 | 1 | S16E14 | 0010 | BXO |
 |
 |
was AR S11724 location: S19E19 |
||
| S11725 | 2025.12.27 | N23W49 | |||||||||
| 14327 | 2025.12.28 2025.12.28 |
S21W77 | was AR S11728 | ||||||||
| 14331 | 2025.12.28 2025.12.29 |
1 | 2 | 1 | S25E24 | 0010 | AXX | HRX |
 |
 |
was AR S11729 |
| 14328 | 2025.12.29 | 5 | S13W21 | 0020 | CSO | leader spots of AR 14323, SWPC classification is obviously wrong | |||||
| 14329| | 2025.12.29 2025.12.29 |
3 | S12E08 | 0005 | AXX |
 |
 |
was AR S11731 location: S14E11 |
|||
| 14332 | 2025.12.30 2025.12.31 |
1 | 6 | 3 | N14E17 | 0010 | AXX | BXO |
 |
 |
was AR S11732 location: N15E18 |
| S11733 | 2025.12.30 | N11W42 | |||||||||
| S11734 | 2025.12.31 | 9 | N03E10 | 0012 | BXO |
 |
 |
||||
| S11735 | 2025.12.31 | 9 | 2 | S22E30 | 0020 | AXX |
 |
 |
|||
| S11737 | 2026.01.01 | 1 | N12W11 | 0001 | AXX |
 |
|||||
| S11738 | 2026.01.01 | 3 | 3 | S09E16 | 0020 | DRO |
 |
||||
| S11739 | 2026.01.01 | 7 | 3 | S11E18 | 0015 | CRO |
 |
||||
| S11740 | 2026.01.01 | 1 | 1 | S15E85 | 0150 | HSX |
 |
||||
| Total spot count: | 50 | 171 | 73 | ||||||||
| Sunspot number: | 120 | 321 | 173 | (total spot count + 10 * number of spotted regions) | |||||||
| Weighted SN: | 75 | 203 | 105 | (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): | 132 | 177 | 138 | ||||||||
| 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 |
| 2024.10 | 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 | 124.7 (-3.8) | 21.43 |
| 2025.07 | 137.8 | 142.3 | 125.6 | (122.4 projected, -2.3) | 11.80 |
| 2025.08 | 154.9 | 158.7 | 133.5 | (119.3 projected, -3.1) | 9.97 |
| 2025.09 | 154.4 | 156.0 | 129.8 | (115.8 projected, -3.5) | 14.02 |
| 2025.10 | 139.5 | 138.6 | 114.6 | (111.8 projected, -4.0) | 15.64 |
| 2025.11 | 140.3 | 137.3 | 91.7 | (109.5 projected, -2.3) | 21.01 |
| 2025.12 | 160.8 | 155.8 | 124.0 | (108.0 projected, -1.5) | 13.8 |
| 2026.01 | 169.2 (1) | 3.9 (2A) / 120 (2B) / 136.6 (2C) | (104.0 projected, -4.0) | (11.4) | |
| 2026.02 | (99.9 projected, -4.1) | ||||
| 2026.03 | (95.5 projected, -4.4) | ||||
| 2026.04 | (91.8 projected, -3.7) | ||||
| 2026.05 | (90.5 projected, -1.3) | ||||
| 2026.06 | (88.4 projected, -2.1) | ||||
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 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.
