The geomagnetic field was at quiet to unsettled levels on April 1. Solar wind speed at SOHO ranged between 389 and 578 km/sec, averaging 443 km/sec (+16 km/sec compared to the previous day). A solar wind shock was observed at 11:43 UT at SOHO, the arrival of the March 30 CME. A high speed stream associated with CH1353 became the dominant solar wind source late in the day and increased disturbance levels early on April 2. The high latitude magnetometer at Andenes was at quiet to minor 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 141.9 - decreasing 4.3 over the previous solar rotation.
The 365 day average solar flux at 1 AU was 144.35 (183 days ago). The 81 day average solar flux at 1 AU was 135.1 (41 days ago, this is 41.8% 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 8 (STAR Ap - based on the average of three hour interval ap indices: 8.4). Three hour interval K indices: 32113212 (planetary), 31113422 (Boulder), 54113332 (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: 234) and in 10 active regions using 1K resolution (SN: 146) SDO/HMI images.
AR 14399 [S16W64] was quiet and stable.
AR 14401 [N25W70] decayed slowly and was mostly quiet. C1 flares:
C1.1 @ 04:26, C1.2 @ 06:56, C1.0 @ 17:19, C1.5 @ 17:45 UT
AR 14402 [N18W56] decayed slowly and quietly.
AR 14403 [N15W25] decayed slowly and was quiet until late in the day.
AR 14404 [N13W07] developed slowly and quietly.
AR 14405 [S28E07] decayed slowly in the leading spot section and was
mostly quiet. C1 flares: C1.0 @ 18:30 UT
AR 14406 [N08W01] was quiet and stable.
AR 14407 [N17E06] decayed slowly and was mostly quiet. C1
flares: C1.0 @ 15:43 UT
AR 14408 [N08E25] was quiet and stable.
AR 14409 [N01E27] gained spots, has polarity intermixing and was the
most active flare producer on the visible disk. C1 flares: C1.2 @ 06:51,
C1.3 @ 11:04, C1.0 @ 17:25, C1.4 @ 21:02, C1.2 @ 22:21, C1.7 @ 22:43 UT
Spotted regions not observed (or interpreted
differently) by SWPC/USAF:
AR S11964 [S14W10] decayed slowly and quietly.
AR S11968 [N10W73] developed further and was
mostly quiet. C1 flares: C1.3 @ 12:53 UT
New AR S11969 [S05E74] rotated into view with tiny spots.
C2+ flares
| Magnitude | Peak time (UT) | Location | Source | Recorded by | Comment |
| C5.3 | 13:48 | 14409 | GOES18 | ||
| C8.1 | 19:58 | 14409 | GOES18 | ||
| C4.8 | 21:51 | 14409 | GOES18 | ||
| C2.2 | 22:48 | 14409 | GOES18 | ||
| C5.2 | 23:00 | 14409 | GOES18 | ||
| C6.1 | 23:27 | 14403 | GOES18 | moderate type II radio sweep | |
| C5.1 | 00:04 | 14409 | GOES18 | flare began at 23:59 UT |
March 30: A full halo CME was observed after the X1.5 flare in AR
14405. A solar wind shock associated with the CME reached Earth on April 1,
however, the geomagnetic effects were minor.
March 31 + April 1: No obviously Earth directed CMEs were observed in
available coronagraph imagery.
April 2: A halo CME was observed in LASCO C3 imagery early in the day
following a large filament eruption near AR 14403 just before midnight on
April 1. A shock from this CME is possible on April 4, however, the bulk of
the ejecta is not heading towards Earth.
[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 trans equatorial negative polarity coronal hole (CH1353) will be in an Earth facing position on March 30 - April 1. A recurrent northern hemisphere negative polarity coronal hole will likely rotate across the central meridian on April 2-4 and could cause a weak disturbance on April 5-6.
The geomagnetic field is expected to be at unsettled to minor storm levels on April 2-4 due to effects associated with CH1353. A shock from the April 1-2 CME could reach Earth on April 4 and contribute to the ongoing disturbance.
| 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 | ||||||||||
| 14399 | 2026.03.21 2026.03.21 |
1 | 1 | 1 | S16W65 | 0050 | HSX | HSX |
 |
 |
was AR S11941 area: 0170 location: S16W64 |
| 14401 | 2026.03.21 2026.03.22 |
5 | 5 | 3 | N25W70 | 0090 | HAX | HAX |
 |
 |
was AR S11942 area: 0170 |
| 14402 | 2026.03.21 2026.03.22 |
3 | 4 | 1 | N19W57 | 0020 | HRX | HRX |
 |
 |
was AR S11943 location: N18W56 |
| 14403 | 2026.03.24 2026.03.25 |
2 | 9 | 3 | N15W26 | 0070 | HSX | CSO |
 |
 |
was AR S11952 area: 0120 |
| 14405 | 2026.03.26 2026.03.27 |
11 | 20 | 9 | S27E05 | 0210 | EAC | EAO |
 |
 |
was AR S11956 area: 0310 location: S28E07 |
| 14404 | 2026.03.26 2026.03.27 |
8 | 19 | 10 | N15W07 | 0060 | CSI | DSI |
 |
 |
was AR S11957 area: 0120 location: N13W07 |
| 14406 | 2026.03.26 2026.03.27 |
1 | 1 | 1 | N08W02 | 0050 | HSX | HSX |
 |
 |
was AR S11958 area: 0130 location: N08W01 |
| S11959 | 2026.03.26 | N07W21 | |||||||||
| 14407 | 2026.03.27 2026.03.28 |
4 | N17E03 | 0005 | BXO |
 |
 |
was AR S11960 location: N17E06 |
|||
| 14408 | 2026.03.28 2026.03.29 |
1 | 4 | 2 | N08E24 | 0040 | HSX | CSO |
 |
 |
was AR S11963 area: 0090 |
| S11964 | 2026.03.28 | 4 | S14W10 | 0006 | AXX |
 |
 |
||||
| 14409 | 2026.03.29 2026.03.30 |
8 | 27 | 14 | N02E24 | 0030 | DRI | DRI |
 |
 |
beta-gamma was AR S11965 area: 0110 location: N01E27 |
| S11966 | 2026.03.29 | S05W45 | |||||||||
| S11967 | 2026.03.29 | S21W31 |
 |
||||||||
| S11968 | 2026.03.31 | 4 | 2 | N10W73 | 0040 | DRO |
 |
 |
|||
| S11969 | 2026.04.01 | 2 | S05E74 | 0004 | AXX |
 |
|||||
| Total spot count: | 40 | 104 | 46 | ||||||||
| Sunspot number: | 130 | 234 | 146 | (total spot count + 10 * number of spotted regions) | |||||||
| Weighted SN: | 81 | 148 | 90 | (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): | 143 | 129 | 117 | ||||||||
| 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) | 15.4 |
| 2026.04 | 141.9 (1) | 4.3 (2A) / 130 (2B) / 102.9 (2C) | (88.7 projected, -4.0) | (8.4) | |
| 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.
