Solar Terrestrial Activity Report

Activity chart

Last major update issued on October 11, 2026 at 12:00 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 (September 1, 2026)
Solar cycle Solar cycles 23-25 (October 1, 2026) Historical solar and geomagnetic data charts 1954-2006 (April 5, 2007)
  Cycle 24-25 progress (October 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 (October 1, 2026) 3rd SSN Workshop, Tucson, 2013
  Comparison of cycles 12-14, 16, 24-25 (October 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 to severe storm levels. A strong solar wind shock was observed at 14:44 UT at SOHO, the arrival of the October 8 CME. Solar wind speed at SOHO ranged between 399 and 873 km/sec, averaging 553 km/sec (+160 km/sec compared to the previous day). The high latitude magnetometer at Andenes was at quiet to severe storm levels. The above 10 MeV proton flux decayed slowly towards background levels.

Solar flux density measured at 20h UT on 2.8 GHz was 125.5 - increasing 18.6 over the previous solar rotation.

The 365 day average solar flux at 1 AU was 131.85 (183 days ago). The 81 day average solar flux at 1 AU was 116.7 (41 days ago, this is 30.1% 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 52 (STAR Ap - based on the average of three hour interval ap indices: 52.4). Three hour interval K indices: 23324776 (planetary), 22433664 (Boulder), 34224775 (Andenes).

The background x-ray flux is at the class B6 level (GOES 19).

At the time of counting spots (see image time), spots were observed in 9 active regions using 2K resolution (SN: 161) and in 6 active regions using 1K resolution (SN: 100) SDO/HMI images.

AR 14545 [N17W60] decayed slowly and was mostly quiet.
AR 14548 [S12W26] was quiet and stable.
AR 14549 [N08W57] still has a strong magnetic delta configuration in the leading spot section. Slow decayed was observed elsewhere. Further major flares are possible. C1 flares: C1.2 @ 00:52, C1.1 @ 01:25, C1.0 @ 02:29, C1.0 @ 07:04, C1.5 @ 04:20, C1.7 @ 09:33, C1.2 @ 12:18 UT
AR 14551 [S14E59] was mostly quiet and stable. M class flaring is possible. C1 flares: C1.0 @ 01:44, C1.4 @ 11:53, C1.6 @ 22:48 UT
AR 14552 [N22W33] decayed slowly and quietly.

Spotted regions not observed (or interpreted differently) by SWPC/USAF:
AR S12410 [S09E38] was quiet and stable.
AR S12411 [S01W54] decayed slowly and quietly.
New AR S12412 [N19E20] emerged with tiny spots.
New AR S12413 [N07E74] rotated into view with tiny spots.

AR 14547 behind the northwest limb was the source of C1 flares: C1.3 @ 05:13, C1.6 @ 08:51, C1.4 @ 09:08, C1.0 @ 11:22 UT

C2+ flares

Magnitude Peak time (UT) Location Source Recorded by Comment
C7.9 04:38 N08W40 14549 GOES18  
C4.2 08:13 behind NW limb 14547 GOES18  
C2.7 13:25   14549 GOES18  
M1.2/1N 14:12 N11W46 14549 GOES18  
C3.9 14:45 behind NW limb 14547 GOES18  
M6.4/1N 15:10   14549 GOES18 CME, LDE, weak type II radio sweep
C3.4 17:35   14551 GOES18  
C4.8 17:52   14551 GOES18  
C2.1 20:18   14545 GOES18  
C2.0 20:40   14549 GOES18  
C3.1 23:20   14545 GOES18  

Coronal mass ejections (CMEs)

October 8: A fast partial halo CME was observed after the major M6 flare in AR 14549. The CME reached Earth on October 10.
October 9: No obviously Earth directed CMEs were observed.
October 10: A faint halo CME component was observed after the M6.4 flare in AR 14549. While the main ejecta was observed off the northwest limb, there is a chance of a solar wind shock on October 13.

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 southern hemisphere negative polarity coronal hole (CH1403) will rotate across the central meridian on October 7-12. A recurrent trans equatorial negative polarity coronal hole (CH1404) will be Earth facing on October 10-12.

Forecast

The geomagnetic field is expected to be at unsettled to active levels on October 11 due to CME effects. High speed streams from CH1403 and CH1404 will likely vecome the dominant solar wind sources October 12-15 and cause quiet to minor storm conditions.

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
14545 2026.09.30
2026.10.01
5 10 7 N17W60 0020 CAO DRI was AR S12387

SWPC classication is not in accordance with the McIntosh classification standard

14548 2026.10.02
2026.10.03
1 3 2 S13W26 0040 HSX HSX was AR S12392

area: 0090

S12393 2026.10.02       S13W55            
14549 2026.10.04
2026.10.05
28 24 16 N09W54 0260 EKI EAC originally reversed polarities

beta-gamma-delta

was AR S12399

area: 0340

SWPC spot count is much higher than expected

location: N08W57

S12400 2026.10.04       N04W57            
S12401 2026.10.05       N13W36          
14550 2026.10.07
2026.10.07
      S16W65           was AR S12404

location: S16W61

S12405 2026.10.07       N12W13            
14552 2026.10.08
2026.10.09
3 6 2 N22W34 0010 BXO BXO was AR S12406

location: N22W33

14551 2026.10.08
2026.10.09
12 19 12 S14E61 0360 EKO EKO was AR S12407

area: 0840

location: S14E59

S12408 2026.10.08       N04W34            
S12409 2026.10.09       N09W25          
S12410 2026.10.09   4   S09E38 0005   BXO  
S12411 2026.10.09   1   S01W54 0001   AXX  
S12412 2026.10.10   2   N19E20 0003   BXO    
S12413 2026.10.10   2 1 N07E74 0007   AXX    
Total spot count: 49 71 40  
Sunspot number: 99 161 100  (total spot count + 10 * number of spotted regions)
Weighted SN: 79 94 63  (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): 99 81 75 (Effective 2026.09.19: SWPC adjustment changed from 1.1 to 1.0, STAR 2K adjustment changed from 0.55 to 0.5, STAR 1K adjustment changed from 0.8 to 0.75)

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
2025.07 137.8 142.3 125.9 122.5 (-2.2) 11.80
2025.08 154.9 158.7 133.7 118.4 (-4.1) 9.97
2025.09 154.4 156.0 129.7 113.1 (-5.3) 14.02
2025.10 139.5 138.6 114.6 108.5 (-4.6) 15.64
2025.11 140.3 137.3 91.7 106.9 (-1.6) 21.01
2025.12 160.8 155.8 124.0 107.0 (-0.1) 13.35
2026.01 148.7 144.0 115.0 104.2 (-2.8) 22.47
2026.02 136.4 133.1 77.4 99.8 (-4.4) 12.88
2026.03 131.0 129.7 86.6 94.5 (-5.3) 15.44
2026.04  120.0 120.9 79.3 (89.6 projected, -4.9) 12.10
2026.05 125.4 128.2 101.4 (87.2 projected, -2.4) 9.80
2026.06 137.9 142.2 94.3 (84.1 projected, -3.1) 9.57
2026.07 134.7 139.0 78.1 (79.2 projected, -4.9) 10.16
2026.08 116.1 119.0 76.0 (77.0 projected, -2.2) 8.67
2026.09 105.0 106.1 60.3 (76.1 projected, -0.9) 7.7
2026.10 106.2 (1)   21.2 (2A) / 65.2 (2B) / 68.0 (2C) (74.0 projected, -2.1) (15.5)
2026.11       (71.2 projected, -2.8)  
2026.12       (68.0 projected, -3.2)  
2027.01       (65.6 projected, -2.4)  
2027.02       (63.8 projected, -1.8)  
2027.03       (62.5 projected, -1.3)  

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.