The geomagnetic field was at quiet to minor storm levels on May 4. What was likely a CME was observed arriving at ACE just after 04h UT with the main part of the disturbance arriving after 14h UT. Solar wind speed at SOHO ranged between 384 and 492 km/sec, averaging 427 km/sec (+5 km/sec compared to the previous day). The high latitude magnetometer at Andenes was at quiet to major storm levels. The above 10 MeV proton flux was at background levels all day.
Solar flux density measured at 20h UT on 2.8 GHz was 138.0 - increasing 29.1 over the previous solar rotation.
The 365 day average solar flux at 1 AU was 140.86 (183 days ago). The 81 day average solar flux at 1 AU was 124.9 (41 days ago, this is 35.3% 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: 195.9 on October 13, 2024.
The Potsdam WDC planetary A index was 20 (STAR Ap - based on the average of three hour interval ap indices: 19.8). Three hour interval K indices: 22233454 (planetary), 23233544 (Boulder), 43233565 (Andenes).
The background x-ray flux is at the class B8 level (GOES 19).
At the time of counting spots (see image time), spots were observed in 13 active regions using 2K resolution (SN: 262) and in 11 active regions using 1K resolution (SN: 186) SDO/HMI images.
AR 14425 [N05W61] decayed slowly and was mostly
quiet. C1 flares: C1.1 @ 07:44, C1.2 @ 11:25, C1.5 @ 11:39, C1.3 @ 16:52,
C1.6 @ 17:04, C1.2 @ 21:55 UT
AR 14428 [S22W68] decayed slowly and was mostly quiet. C1 flares:
C1.0 @ 04:36 UT
AR 14429 [S04W21] decayed slowly and was mostly quiet. C1 flares:
C1.2 @ 10:51 UT
AR 14431 [S16E08] was mostly quiet and stable. C1 flares: C1.2 @
19:00 UT
AR 14432 [N12E27] developed further and has polarity intermixing.
C1.1 @ 13:27, C1.3 @ 16:41, C1.4 @ 17:32, C1.2 @ 19:54, C1.1 @ 23:45 UT
AR 14433 [S16E54] was mostly quiet and stable. C1 flares: C1.3 @
18:48 UT
New AR 14434 [N12E50] rotated into view on May 2 and was numbered by
SWPC 2 days later.
New AR 14435 [N23E63] rotated into view on May 3 and received its
NOAA number the next day. C1 flares: C1.5 @ 22:07 UT
Spotted regions not observed (or interpreted
differently) by SWPC/USAF:
AR S12034 [S18W43] reemerged with a tiny spot.
New AR S12039 [S10W21] emerged with tiny spots.
New AR S12040 [S10E37] emerged with tiny spots.
New AR S12041 [N11W40] emerged with a tiny spot.
New AR S12042 [N26W05] emerged with a tiny spot.
AR 14424 was the source of a C1.1 flare at 13:52 UT
C2+ flares
| Magnitude | Peak time (UT) | Location | Source | Recorded by | Comment |
| M1.8 | 01:33 | 14424 | GOES18 |
May 2-4: 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 trans equatorial coronal hole (CH1363) could rotate across the central meridian on May 4-7.
The geomagnetic field is expected to be at quiet to minor storm levels on May 5 due to CME effects. Mostly quiet conditions are likely on May 6. Quiet to minor storm conditions are possible on May 7-8 due to effects from CH1363.
| 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 | ||||||||||
| 14424 | 2026.04.23 2026.04.24 |
5 | N17W92 | 0110 | DAO |
 |
was AR S12010 rotated out of view location: N16W90 SWPC has copied sunspot data from the previous day |
||||
| 14425 | 2026.04.24 2026.04.24 |
2 | 2 | 2 | N05W61 | 0170 | HSX | HKX |
 |
 |
was AR S12011 area: 0320 |
| 14427 | 2026.04.24 2026.04.25 |
S29W56 |
was AR S12013 location: S31W49 |
||||||||
| 14428 | 2026.04.27 2026.04.28 |
9 | 15 | 7 | S23W65 | 0220 | EAO | EAO |
 |
 |
was AR S12022 area: 0250 location: S22W68 |
| 14429 | 2026.04.29 2026.04.30 |
16 | 37 | 23 | S05W20 | 0075 | CAI | DAI |
 |
 |
was AR S12025 area: 0110 location: S04W21 |
| 14431 | 2026.04.29 2026.05.01 |
5 | 28 | 15 | S16E12 | 0110 | ESO | EHO |
 |
 |
was AR S12026 area: 0300 location: S16E08 |
| 14430 | 2026.04.29 2026.05.01 |
N17W72 |
 |
was AR S12027 | |||||||
| S12029 | 2026.04.30 | N07W46 | |||||||||
| S12030 | 2026.04.30 | N27W33 | |||||||||
| 14432 | 2026.05.01 2026.05.01 |
6 | 24 | 15 | N13E27 | 0010 | CAI | DRI |
 |
 |
beta-gamma area: 0100 location: N12E27 |
| S12033 | 2026.05.01 | N46W17 | |||||||||
| S12034 | 2026.05.01 | 1 | S18W43 | 0001 | AXX |
 |
|||||
| 14433 | 2026.05.02 2026.05.03 |
8 | 12 | 7 | S16E57 | 0090 | DSO | DAO |
 |
 |
was AR S12035 area: 0220 location: S16E54 |
| 14434 | 2026.05.02 2026.05.04 |
1 | 4 | 2 | N12E50 | 0010 | AXX | CRO |
 |
 |
was AR S12036 area: 0020 |
| 14435 | 2026.05.03 2026.05.04 |
1 | 1 | 1 | N23E64 | 0030 | HSX | HSX |
 |
 |
was AR S12037 area: 0100 location: N23E63 |
| S12038 | 2026.05.03 | N29W20 |
 |
||||||||
| S12039 | 2026.05.04 | 3 | 2 | S10W21 | 0012 | BXO |
 |
||||
| S12040 | 2026.05.04 | 3 | 1 | S10E37 | 0008 | AXX |
 |
||||
| S12041 | 2026.05.04 | 1 | 1 | N11W40 | 0002 | AXX |
 |
||||
| S12042 | 2026.05.04 | 1 | N26W05 | 0001 | AXX |
 |
|||||
| Total spot count: | 53 | 132 | 76 | ||||||||
| Sunspot number: | 143 | 262 | 186 | (total spot count + 10 * number of spotted regions) | |||||||
| Weighted SN: | 93 | 178 | 122 | (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): | 157 | 144 | 149 | ||||||||
| 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 |
| 2025.02 | 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 | 108.3 (-4.6) | 15.64 |
| 2025.11 | 140.3 | 137.3 | 91.7 | (105.8 projected, -2.5) | 21.01 |
| 2025.12 | 160.8 | 155.8 | 124.0 | (104.3 projected, -1.5) | 13.35 |
| 2026.01 | 148.7 | 144.0 | 112.6 | (100.4 projected, -3.9) | 22.47 |
| 2026.02 | 136.4 | 133.1 | 78.2 | (96.1 projected, -4.3) | 12.88 |
| 2026.03 | 131.0 | 129.7 | 85.9 | (91.5 projected, -4.6) | 15.44 |
| 2026.04 | 120.0 | 120.9 | 79.3 | (87.6 projected, -3.9) | 12.0 |
| 2026.05 | 146.2 (1) | 18.5 (2A) / 143.0 (2B) / 92.4 (2C) | (86.4 projected, -1.2) | (11.7) | |
| 2026.06 | (84.3 projected, -2.1) | ||||
| 2026.07 | (79.9 projected, -4.4) | ||||
| 2026.08 | (77.7 projected, -2.2) | ||||
| 2026.09 | (76.8 projected, -0.9) | ||||
| 2026.10 | (74.8 projected, -2.0) | ||||
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.
