The geomagnetic field was at quiet to unsettled levels on August 27. Solar wind speed at SOHO ranged between 332 and 415 km/sec, averaging 362 km/sec (-20 km/sec compared to the previous day). The high latitude magnetometer at Andenes recorded quiet to active levels. The above 10 MeV proton flux decreased slowly after peaking at 13.9 pfu at 07:40 UT, ending the day at 6.8 pfu.
Solar flux density measured at 17h UT on 2.8 GHz was 225.7 - increasing 80.9 over the previous solar rotation. The 365 day average solar flux at 1 AU was 172.21 (183 days ago). The 81 day average solar flux at 1 AU was 143.4 (41 days ago, this is 46.3% 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: 195.86 on October 13, 2024. The Potsdam WDC planetary A index was 7 (STAR Ap - based on the average of three hour interval ap indices: 6.9). Three hour interval K indices: 21123222 (planetary), 21114322 (Boulder), 32133344 (Andenes).
The background x-ray flux is at the class C2 level (GOES 19).
At the time of counting spots (see image time), spots were observed in 15 active regions using 2K resolution (SN: 367) and in 15 active regions using 1K resolution (SN: 272) SDO/HMI images.
AR 14188 [S08W48] decayed slowly and quietly.
AR 14190 [N19W41] decayed slowly and quietly.
AR 14191 [N10W13] decayed significantly in the trailing and
intermediate spot sections.
AR 14194 [N03W28] was quiet and stable.
AR 14195 [S16E17] decayed slowly and quietly.
AR 14196 [S11E25] decayed slowly and quietly.
AR 14197 [S18E27] developed further gaining spots and area. There is a small magnetic delta in
the leader penumbra. A major flare is possible.
AR 14198 [N10E07] decayed slowly and was mostly quiet.
AR 14199 [N03E45] decayed slowly. SWPC has split off the trailing
spot section into AR 14204.
AR 14200 [S08W12] developed slowly and was mostly quiet.
AR 14201 [S21E43] gained a small magnetic delta in an intermediate
spot section penumbra.
AR 14202 [S15E48] decayed slowly and quietly.
AR 14203 [N12W72] developed slowly and quietly.
Spotted regions not observed (or interpreted
differently) by SWPC/USAF:
S11383 [N17E22] was quiet and stable.
New AR S11388 [S20W43] emerged with a tiny spot.
C2+ flares
| Magnitude | Peak time (UT) | Location | Source | Recorded by | Comment |
| C6.2 | 00:22 | 14199 | GOES18 | ||
| C3.7 | 01:00 | 14191 | GOES18 | ||
| C3.8 | 03:09 | 14199 | GOES18 | ||
| C3.3 | 04:17 | 14199 | GOES18 | ||
| C3.2 | 06:11 | 14197 | GOES18 | ||
| C2.3 | 07:26 | 14197 | GOES18 | ||
| C2.9 | 08:37 | 14199 | GOES18 | ||
| C2.6 | 09:03 | 14197 | GOES18 | ||
| C2.1 | 10.05 | 14199 | GOES18 | ||
| C2.6 | 11:04 | 14197 | GOES18 | ||
| C2.6 | 12:15 | 14197 | GOES18 | ||
| C5.5 | 12:37 | 14199 | GOES18 | ||
| C9.2 | 12:50 | N05E56 | 14199 | GOES18 | |
| C4.4 | 13:57 | 14199 | GOES18 | ||
| C5.4 | 14:33 | N07E55 | 14199 | GOES18 | |
| C2.9 | 15:45 | 14197 | GOES18 | ||
| C2.8 | 16:42 | 14197 | GOES18 | ||
| C2.5 | 16:55 | 14197 | GOES18 | ||
| C3.0 | 17:23 | 14197 | GOES18 | ||
| C4.1 | 20:03 | 14198 | GOES18 | ||
| C3.8 | 21:14 | 14199 | GOES18 | ||
| C4.5 | 21:19 | 14200 | GOES18 | ||
| C4.3 | 22:02 | 14200 | GOES18 | ||
| C3.5 | 22:53 | 14197 | GOES18 |
August 25-27: No obviously Earth directed CMEs.
[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 negative polarity northern hemisphere coronal hole (CH1313) was Earth facing on August 22-24. A recurrent negative polarity southern hemisphere coronal hole (CH1314) will rotate across the central meridian on August 28. CH1314 has decayed over the last days and is about to close.
The geomagnetic field is expected to be at mostly quiet levels on August 28-30. August 31 could see quiet to unsettled levels due to effects associated with CH1314.
| 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 | ||||||||||
| 14188 | 2025.08.17 2025.08.18 |
1 | 6 | 2 | S09W50 | 0030 | HSX | CRO |
 |
 |
was AR S11359 location: S08W48 |
| 14189 | 2025.08.18 2025.08.19 |
N08W65 | was AR S11360 | ||||||||
| 14190 | 2025.08.19 2025.08.20 |
1 | 4 | 2 | N19W42 | 0010 | AXX | BXO |
 |
 |
was AR S11362 location: N19W41 |
| 14191 | 2025.08.20 2025.08.20 |
13 | 37 | 17 | N12W13 | 0400 | EHI | EHI |
 |
 |
was AR S11363 location: N10W13 area: 0560 |
| 14193 | 2025.08.20 2025.08.2? |
S27W58 |
was AR S11368 location: S26W54 |
||||||||
| 14194 | 2025.08.22 2025.08.2? |
2 | 6 | 1 | N03W29 | 0010 | AXX | CRO |
 |
 |
was AR S11373 area: 0020 location: N03W28 |
| 14195 | 2025.08.22 2025.08.2? |
1 | 8 | 2 | S18E14 | 0010 | AXX | BXO |
 |
 |
was AR S11374 location: S16E17 area: 0015 |
| 14197 | 2025.08.23 2025.08.24 |
29 | 72 | 50 | S17E30 | 0720 | EKI | EKC |
 |
 |
beta-gamma-delta was AR S11375 area: 1120 location: S18E27 |
| 14196 | 2025.08.23 2025.08.24 |
1 | 4 | 2 | S12E25 | 0010 | HRX | HRX |
 |
 |
was AR 11376 location: S11E25 area: 0025 |
| 14198 | 2025.08.24 2025.08.25 |
2 | 8 | 5 | N11E07 | 0010 | BXO | DRO |
 |
 |
was AR S11379 area: 0025 location: N10E07 |
| 14200 | 2025.08.24 2025.08.26 |
11 | 23 | 13 | S08W14 | 0040 | DAI | DAI |
 |
 |
was AR S11380 area: 0150 location: S08W12 |
| 14199 | 2025.08.24 2025.08.25 |
9 | 18 | 10 | N04E45 | 0170 | CAO | CAO |
 |
 |
was AR S11381 location: N03E45 area: 0350 |
| 14201 | 2025.08.24 2025.08.26 |
7 | 15 | 8 | S21E44 | 0100 | DSI | DAC |
 |
 |
beta-delta was AR S11382 location: S21E55 |
| S11383 | 2025.08.24 | 3 | 1 | N17E22 | 0005 | BXO |
 |
 |
|||
| S11384 | 2025.08.24 | S19W19 | |||||||||
| 14202 | 2025.08.25 2025.08.26 |
2 | 3 | 3 | S15E48 | 0150 | HAX | CHO |
 |
 |
was AR S11385 area: 0280 |
| 14203 | 2025.08.25 2025.08.26 |
7 | 9 | 5 | N12W75 | 0060 | DAO | CAO |
 |
 |
was AR S11386 |
| S11387 | 2025.08.26 | S26W19 |
 |
||||||||
| 14204 | 2025.08.27 | 1 | N03E57 | 0010 | HRX | trailing spot of AR 14199 | |||||
| S11388 | 2025.08.27 | 1 | 1 | S20W43 | 0002 | AXX |
 |
||||
| Total spot count: | 87 | 217 | 122 | ||||||||
| Sunspot number: | 227 | 367 | 272 | (total spot count + 10 * number of spotted regions) | |||||||
| Weighted SN: | 143 | 279 | 184 | (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): | 250 | 202 | 218 | ||||||||
| Month | Average solar flux | International sunspot number (WDC-SILSO) |
Smoothed sunspot number (4) | Average
ap (3) |
|
|---|---|---|---|---|---|
| Measured | 1 AU | ||||
| 2024.02 | 172.5 | 168.3 | 123.0 | 136.9 (+5.7) | 5.31 |
| 2024.03 | 154.4 | 152.9 | 103.7 | 141.4 (+4.5) | 11.03 |
| 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 | (139.4 projected, -6.9) | 14.42 |
| 2025.03 | 163.7 | 162.1 | 134.2 | (133.4 projected, -6.0) | 15.96 |
| 2025.04 | 162.5 | 163.6 | 140.6 | (129.3 projected, -4.1) | 17.62 |
| 2025.05 | 135.3 | 138.3 | 79.2 | (124.4 projected, -4.9) | 17.26 |
| 2025.06 | 131.3 | 135.4 | 116.3 | (119.6 projected, -4.8) | 21.43 |
| 2025.07 | 137.8 | 142.3 | 125.6 | (115.6 projected, -4.0) | 11.80 |
| 2025.08 | 144.9 (1) | 109.0 (2A) / 125.1 (2B) / 145.1 (2C) ISN average: 130.7. At this level the SSN for February 2025 will become 139.8 |
(110.9 projected, -4.7) | (10.4) | |
| 2025.09 | (106.5 projected, -4.4) | ||||
| 2025.10 | (102.6 projected, -3.9) | ||||
| 2025.11 | (100.3 projected, -2.3) | ||||
| 2025.12 | (98.7 projected, -1.6) | ||||
| 2026.01 | (94.6 projected, -4.1) | ||||
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 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.
