Solar Terrestrial Activity Report

Activity chart

Last major update issued on May 10, 2026 at 08:05 UT.

Charts (* = updated daily) Data and archive
  Solar wind (*) Solar and geomagnetic data - last month (*)
  Electron fluence (*) Archived daily reports and monthly data since 2003.01 (May 1, 2026)
Solar cycle Solar cycles 23-25 (May 1, 2026) Historical solar and geomagnetic data charts 1954-2006 (April 5, 2007)
  Cycle 24-25 progress (May 1, 2026) Noon SDO sunspot count 1K image / 4K (*)
  Solar cycles 1-24 (August 1, 2020) POES auroral activity level [October 2009 - December 2012]
  Comparison of cycles 21-25 (May 1, 2026) 3rd SSN Workshop, Tucson, 2013
  Comparison of cycles 12-14, 16, 24-25 (May 1, 2026) 4th SSN Workshop, Locarno, 2014
  Solar polar fields vs. solar cycles (December 21, 2025) Cycle 25 initial spots (final update December 25, 2019)
  Solar cycles 24-25 transition using 365d smoothing  

Recent activity

The geomagnetic field was at quiet levels, very weakly under the influence of effects associated with CH1363. Solar wind speed at SOHO ranged between 489 and 602 km/sec, averaging 518 km/sec (+15 km/sec compared to the previous day). The high latitude magnetometer at Andenes was at quiet to unsettled levels. The above 10 MeV proton flux was at background levels all day.

Solar flux density measured at 17h UT on 2.8 GHz was 121.5 - increasing 22.7 over the previous solar rotation. The measurement at 20h UT was unavailable when this was written.

The 365 day average solar flux at 1 AU was 140.44 (183 days ago). The 81 day average solar flux at 1 AU was 125.4 (41 days ago, this is 35.6% 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 4 (STAR Ap - based on the average of three hour interval ap indices: 4.5). Three hour interval K indices: 21111111 (planetary), 22111211 (Boulder), 33112312 (Andenes).

The background x-ray flux is at the class B7 level (GOES 19).

At the time of counting spots (see image time), spots were observed in 9 active regions using 2K resolution (SN: 169) and in 7 active regions using 1K resolution (SN: 114) SDO/HMI images.

AR 14431 [S16W61] was mostly quiet and stable.
AR 14432 [N13W42] gained area and became a compact region with major flare potential. The region produced nearly all of the low level C flares recorded during the day. C1 flares: C1.3 @ 00:21, C1.0 @ 01:48, C1.0 @ 02:58, C1.1 @ 03:07, C1.2 @ 04:23, C1.1 @ 04:45, C1.5 @ 05:21, C1.4 @ 05:37, C1.5 @ 06:33, C1.6 @ 08:02, C1.2 @ 09:24, C1.0 @ 09:57, C1.0 @ 13:11, C1.3 @ 13:19, C1.5 @ 14:31, C1.5 @ 15:26, C1.4 @ 15:32, C1.1 @ 16:25, C1.0 @ 16:43, C1.0 @ 17:05, C1.0  @ 17:54, C1.2 @ 18:55, C1.1 @ 19:20, C1.2 @ 20:29, C1.0 @ 21:03, C1.3 @ 23:06, C1.4 @ 23:21, C1.7 @ 23:42 UT
AR 14433 [S16W12] was quiet and stable.
AR 14435 [N23W01] was quiet and stable.
New AR 14436 [N18E68] rotated into view on May 8 and was numbered the next day by SWPC. The region appears to have a weak magnetic delta configuration in the largest penumbra and is compact. There is a chance of an M class flare, however, the spot group was quiet.

Spotted regions not observed (or interpreted differently) by SWPC/USAF:
AR S12052 [S20E38] developed slowly and quietly.
New AR S12054 [N20E32] emerged with tiny spots.
New AR S12055 [N02E13] was observed with tiny spots in an old plage area.
New AR S12056 [S09W41] emerged with a tiny spot.

C2+ flares

Magnitude Peak time (UT) Location Source Recorded by Comment
C2.1 02:28   14432 GOES18  
C2.3 03:31   14432 GOES18  
C2.0 21:46   14432 GOES18  
C2.1 22:03   14432 GOES18  

Coronal mass ejections (CMEs)

May 7-9: No obviously Earth directed CMEs were observed in available coronagraph imagery.

Coronal holes

[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 (CH1364) will be Earth facing on May 7-9. A recurrent positive polarity southern hemisphere coronal hole (CH1365) will rotate across the central meridian on May 9-10. A recurrent negative polarity trans equatorial coronal hole (CH1366) is expected to become Earth facing on May 12-14.

Forecast

The geomagnetic field is expected to be at quiet to unsettled levels on May 10-13 due to effects associated with CH1363, CH1364 and CH1365.

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.

Active solar regions



(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
14431 2026.04.29
2026.05.01
1 3 2 S16W61 0100 HSX CSO was AR S12026

area: 0160

14432 2026.05.01
2026.05.01
22 40 25 N14W42 0200 DAI EKC

beta-gamma

area: 0620

location: N13W42

14433 2026.05.02
2026.05.03
4 14 9 S17W10 0110 CAO CAO was AR S12035

area: 0170

location: S16W12

14434 2026.05.02
2026.05.04
      N14W18         was AR S12036

location: N13W15

14435 2026.05.03
2026.05.04
1 7 2 N23W01 0050 HSX CSO was AR S12037

area: 0070

S12040 2026.05.04       S10W28            
S12044 2026.05.05       S08W32            
S12047 2026.05.07       S28W47            
S12048 2026.05.08       S19W41          
S12049 2026.05.08       S33E11          
S12050 2026.05.08       S30E23          
14436 2026.05.08
2026.05.09
3 6 3 N18E69 0200 DSO DKC was AR S12051

area: 0360

location: N18E68

S12052 2026.05.08   3 2 S20E38 0008   BXO  
S12054 2026.05.09   3 1 N20E32 0006   BXO    
S12055 2026.05.09   2   N02E13 0003   AXX    
S12056 2026.05.09   1   S09W41 0002   AXX    
Total spot count: 31 79 44  
Sunspot number: 81 169 114  (total spot count + 10 * number of spotted regions)
Weighted SN: 56 114 79  (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): 89 93 91  

Monthly solar cycle data

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) 12.10
2026.05  132.2 (1)   32.6 (2A) / 112.3 (2B) / 94.0 (2C) (86.4 projected, -1.2) (9.3)
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 cycles 24-25

Smoothed SF and sunspot numbers

Update on the progress of solar cycle 25 as of March 2026

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.

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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.