The geomagnetic field was at quiet to unsettled levels on April 25. Solar wind speed at SOHO ranged between 377 and 459 km/sec, averaging 424 km/sec (+17 km/sec compared to the previous day). The phi angle was mainly in a positive sector until about 16:30 UT at ACE, then swung into a negative sector until 19:30 UT. It is uncertain if this was caused by a weak CIR ahead of CH1359 or by weak effects associated with a CME (due to the relatively low solar wind speed, the potential CME source from April 23 is questionable). After 19:30 UT the phi angle has been in a positive sector while solar wind speed has increased slowly suggesting the influence of effects from CH1359. The high latitude magnetometer at Andenes was at quiet to minor storm levels. The above 10 MeV proton flux was just above background levels.
Solar flux density measured at 20h UT on 2.8 GHz was 148.4 - decreasing 9.5 over the previous solar rotation.
The 365 day average solar flux at 1 AU was 141.02 (183 days ago). The 81 day average solar flux at 1 AU was 125.1 (41 days ago, this is 35.4% 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 9 (STAR Ap - based on the average of three hour interval ap indices: 8.6). Three hour interval K indices: 31111233 (planetary), 30112233 (Boulder), 52111254 (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 9 active regions using 2K resolution (SN: 249) and in 7 active regions using 1K resolution (SN: 150) SDO/HMI images.
AR 14420 [N17W00] displayed signs of decay with
only a small magnetic delta configuration remaining. A few low level C
flares were recorded. M flares are possible. C1 flares: C1.3 @ 04:28, C1.1 @
15:19, C.4 @ 16:51, C1.4 @ 18:11, C1.2 @ 18:35, C1.4 @ 22:51 UT
AR 14421 [S11E10] gained a few spots and was quiet.
AR 14423 [S04E17] decayed quickly and lost most of the magnetic delta
configuration that formed on the previous day. C1 flares: C1.2 @ 05:54, C1.3
@ 10:51, C1.2 @ 10:59, C1.9 @ 13:34, C1.9 @ 23:48 UT
AR 14424 [N17E33] developed gaining spots, area and magnetic
complexity. C1 flares: C1.2 @ 10:45, C1.2 @ 12:55, C1.2 @ 16:28, C1.5 @
17:25 UT
AR 14425 [N06E62] gained many spots and has a magnetic delta
configuration in the trailing spot section. M flares are possible. C1
flares: C1.6 @ 00:05, C1.5 @ 02:46, C1.3 @ 04:28, C1.2 @ 05:31, C1.6 @
06:49, C1.3 @ 07:08, C1.8 @ 09:15, C1.4 @ 12:31, C1.4 @ 14:14, C1.7 @ 22:57
UT
New AR 14426 [N12W38] emerged on April 24 and was numbered the next
day by SWPC as the region began to decay.
New AR 14427 [S30E65] rotated into view on April 24 and received its
NOAA number the next day.
Spotted regions not observed (or interpreted
differently) by SWPC/USAF:
AR S12003 [N24W17] was quiet and stable.
New AR S12017 [N12W47] emerged with a tiny spot.
AR 14419 produced C1 flares while rotating over the northwest limb: C1.5 @ 05:02, C1.3 @ 18:45 UT
C2+ flares
| Magnitude | Peak time (UT) | Location | Source | Recorded by | Comment |
| C2.7 | 00:25 | 14420 | GOES18 | ||
| C4.6 | 01:33 | S07E34 | 14423 | GOES18 | |
| C2.3 | 02:10 | 14419 | GOES18 | ||
| C2.2 | 02:20 | 14420 | GOES18 | ||
| C2.5 | 07:46 | 14425 | GOES18 | ||
| M1.3 | 07:59 | S05E27 | 14423 | GOES18 | |
| C8.2 | 08:06 | 14419 | GOES18 | ||
| C2.1 | 09:32 | 14425 | GOES18 | ||
| C3.2 | 09:54 | N17E10 | 14420 | GOES18 | |
| C2.2 | 10:02 | 14423 | GOES18 | ||
| C3.8 | 13:20 | 14419 | GOES18 | ||
| M1.1 | 14:30 | 14425 | GOES18 | ||
| C2.1 | 16:02 | 14419 | GOES18 | ||
| C3.9 | 19:38 | 14420 | GOES18 | ||
| C2.0 | 20:22 | 14419 | GOES18 | ||
| C2.1 | 20:34 | 14420 | GOES18 | ||
| C2.0 | 20:50 | 14425 | GOES18 | ||
| C3.5 | 21:26 | 14423 | GOES18 | ||
| C2.7 | 21:42 | 14425 | GOES18 |
April 23: Multiple CMEs were observed in conjunction with the M
flares. One of them, produced by an M1.2 flare in AR 14420 peaking at 04:58
UT, appears to have some Earth directed components.
April 24: Partial halo CMEs were observed after the major flares in
AR 14419. While the main ejecta are not headed towards Earth, there is a
chance of solar wind shocks on April 26.
April 25: No obviously Earth directed CMEs were observed in
available coronagraph imagery.
[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 northern hemisphere coronal hole (CH1359) was Earth facing on April 22-23. A recurrent negative polarity southern hemisphere coronal hole (CH1361) will likely rotate across the central meridian on April 26-27.
The geomagnetic field is expected to be at quiet to active levels on April 26-27 due to effects associated with CH1359. The April 23 CME could contribute to the disturbance on April 26. Mostly quiet levels are likely on April 28. Effects assocaited with CH1361 could cause quiet to active levels on April 29-30.
| 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 | ||||||||||
| 14419 | 2026.04.12 2026.04.13 |
N15W92 |
 |
was AR S11991 |
|||||||
| S12003 | 2026.04.20 | 5 | N24W17 | 0007 | BXO |
 |
 |
||||
| 14420 | 2026.04.20 2026.04.21 |
53 | 30 | FKC |
 |
 |
beta-gamma-delta was AR S12004 area: 0680 location: N17W00 |
||||
| 14421 | 2026.04.20 2026.04.21 |
15 | 6 | CAO |
 |
 |
was AR S12005 area: 0110 location: S11E10 |
||||
| 14422 | 2026.04.21 2026.04.21 |
N08W87 |
 |
was AR S12006 | |||||||
| S12007 | 2026.04.21 | N11W34 | |||||||||
| 14423 | 2026.04.23 2026.04.24 |
21 | 13 | DAC |
 |
 |
beta-delta was AR S12009 area: 0110 location: S04E17 |
||||
| 14424 | 2026.04.23 2026.04.24 |
31 | 15 | DAI |
 |
 |
beta-gamma was AR S12010 area: 0250 location: N18E33 |
||||
| 14425 | 2026.04.24 2026.04.24 |
26 | 12 | EAC |
 |
 |
beta-gamma-delta was AR S12011 area: 0300 location: N06E62 |
||||
| 14426 | 2026.04.24 2026.04.25 |
5 | 3 | CRO |
 |
 |
was AR S12012 area: 0020 location: N12W38 |
||||
| 14427 | 2026.04.24 2026.04.25 |
2 | 1 | HRX |
 |
 |
was AR S12013 area: 0030 location: S30E65 |
||||
| S12014 | 2026.04.24 | N20E21 |
 |
||||||||
| S12015 | 2026.04.24 | N12E54 |
 |
||||||||
| S12016 | 2026.04.24 | S23W24 |
 |
||||||||
| S12017 | 2026.04.25 | 1 | N12W47 | 0001 | AXX |
 |
|||||
| Total spot count: | 74 | 159 | 80 | ||||||||
| Sunspot number: | 154 | 249 | 150 | (total spot count + 10 * number of spotted regions) | |||||||
| Weighted SN: | 195 | 116 | (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): | 169 | 137 | 120 | ||||||||
| 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 |
| 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 | 128.6 (-4.7) | 17.26 |
| 2025.06 | 131.3 | 135.4 | 114.6 | 124.7 (-3.9) | 21.43 |
| 2025.07 | 137.8 | 142.3 | 125.9 | 122.4 (-2.3) | 11.80 |
| 2025.08 | 154.9 | 158.7 | 133.7 | 118.2 (-4.2) | 9.97 |
| 2025.09 | 154.4 | 156.0 | 129.7 | 112.9 (-5.3) | 14.02 |
| 2025.10 | 139.5 | 138.6 | 114.6 | (108.9 projected, -4.0) | 15.64 |
| 2025.11 | 140.3 | 137.3 | 91.7 | (106.9 projected, -2.0) | 21.01 |
| 2025.12 | 160.8 | 155.8 | 124.0 | (105.4 projected, -1.5) | 13.35 |
| 2026.01 | 148.7 | 144.0 | 112.6 | (101.5 projected, -3.9) | 22.47 |
| 2026.02 | 136.4 | 133.1 | 78.2 | (97.3 projected, -4.2) | 12.88 |
| 2026.03 | 131.0 | 129.7 | 85.9 | (92.7 projected, -4.6) | 15.44 |
| 2026.04 | 114.6 (1) | 68.7 (2A) / 82.5 (2B) / 88.0 (2C) ISN month to date: 77. At this level the SSN for October 2025 will become 108.3 |
(88.7 projected, -4.0) | (13.2) | |
| 2026.05 | (87.5 projected, -1.2) | ||||
| 2026.06 | (85.4 projected, -2.1) | ||||
| 2026.07 | (81.0 projected, -4.4) | ||||
| 2026.08 | (78.8 projected, -2.2) | ||||
| 2026.09 | (77.9 projected, -0.9) | ||||
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
Solar activity appears to have exited the solar max phase as of February
2026 with a strong decrease in the number of sunspots observed. The northern
polar field has weakened considerably over the last months, and although
there is a chance the the field could recover over the next 1-2 years, there
is an increasing chance that solar cycle 26 will be very weak. The southern
polar field is not impressive either, however, a southern polar coronal hole
has formed early in 2026 and appears to be growing.
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.
