Solar Terrestrial Activity Report

Activity chart

Last major update issued on August 16, 2026 at 07:45 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 (August 3, 2026)
Solar cycle Solar cycles 23-25 (August 1, 2026) Historical solar and geomagnetic data charts 1954-2006 (April 5, 2007)
  Cycle 24-25 progress (August 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 (August 1, 2026) 3rd SSN Workshop, Tucson, 2013
  Comparison of cycles 12-14, 16, 24-25 (August 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 unsettled levels. Solar wind speed at SOHO ranged between 349 and 392 km/sec, averaging 367 km/sec (+3 km/sec compared to the previous day). The high latitude magnetometer at Andenes was at quiet to active levels. The above 10 MeV proton flux was at background levels.

Solar flux density measured at 20h UT on 2.8 GHz was 117.1 - decreasing 2.2 over the previous solar rotation.

The 365 day average solar flux at 1 AU was 138.83 (183 days ago). The 81 day average solar flux at 1 AU was 135.5 (41 days ago, this is 42.0% 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 5 (STAR Ap - based on the average of three hour interval ap indices: 5.1). Three hour interval K indices: 11011231 (planetary), 11022221 (Boulder), 32113334(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 10 active regions using 2K resolution (SN: 202) and in 9 active regions using 1K resolution (SN: 147) SDO/HMI images.

AR 14503 [S15W82] decayed slowly and quietly.
AR 14506 [N11W29] developed further, has polarity intermixing and minor M class flare potential. C1 flares: C1.2 @ 00:33, C1.0 @ 09:28 UT
AR 14507 [N04W14] developed gaining spots and polarity intermixing. M flares are possible.
AR 14508 [N08E16] was mostly quiet and stable.
AR 14510 [N13W45] decayed slowly and quietly.
AR 14511 [S10E41] gained tiny trailing spots and was quiet.
New AR 14512 [S20W14] emerged on August 13 and was numbered 2 days later by SWPC as the spot group developed slowly.

Spotted regions not observed (or interpreted differently) by SWPC/USAF:
AR S12289 [N09E00] reemerged with a tiny spot.
AR S12293 [S12E27] was quiet and stable.
New AR S12298 [S14E36] emerged with tiny spots.

C2+ flares

Magnitude Peak time (UT) Location Source Recorded by Comment
C3.3/1N 08:18   14508 GOES18  
C2.0 13:39   14507 GOES18  
C3.2 14:49   14507 GOES18  
C2.7 14:53   14507 GOES18  

Coronal mass ejections (CMEs)

August 13, 15: No obviously Earth directed CMEs were observed in available coronagraph imagery.
August 14: A significant filament eruption was observed beginning after 02h UT in SDO/AIA imagery. The major part of the eruption was just south of the equator in the southeast quadrant between ARs 14507 and S12292. While there was no impressive CME after this event, it is likely that a CME will reach Earth on August 17. A second eruption was observed just north of AR 14507 around 11-12 UT and appears to have been the source of a partial halo CME. This CME could reach Earth as well on August 17.

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 negative polarity southern hemisphere coronal hole (CH1393) will be Earth facing on August 15-18. A recurrent negative polarity northern hemisphere coronal hole (CH1394) will rotate across the central meridian on August 17-18.

Forecast

The geomagnetic field is expected to be at quiet levels on August 16. Quiet to minor storm levels are possible on August 17-18 due to effects associated with the August 14 CMEs. Effects from CH1393 and 1394 could cause unsettled to major storm levels on August 18-21.

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
14503 2026.08.04
2026.08.04
3 2 2 S17W81 0070 CSO CAO was AR S12270

area: 0100

location: S15W82

14504 2026.08.05
2026.08.07
      S19W70           was AR S12273

location: S19W60

S12278 2026.08.06       S07W52            
14506 2026.08.09
2026.08.10
6 26 16 N11W31 0010 DRI DAI

beta-gamma

was AR S12280

area: 0130

location: N11W29

14507 2026.08.10
2026.08.11
13 46 26 N04W15 0140 DAI DAI

beta-gamma

was AR S12283

area: 0350

location: N04W14

14508 2026.08.10
2026.08.11
3 9 4 N08E15 0060 CSO CSO

was AR S12284

area: 0120

14510 2026.08.11
2026.08.13
1 1 1 N12W44 0010 HRX HRX was AR S12287

area: 0020

location: N13W45

S12288 2026.08.11       N27W30            
S12289 2026.08.11   1   N09E00 0001   AXX    
14509 2026.08.12
2026.08.13
2     N10W89 0030 CSO     was AR S12290

rotated out of view

14511 2026.08.12
2026.08.13
1 3 2 S09E40 0010 AXX BXO was AR S12291

location: S10E41

14512 2026.08.13
2026.08.15
2 3 3 S19W15 0010 CRO DRO was AR S12292

area: 0015

location: S20W14

S12293 2026.08.13   6 1 S12E27 0012   BXO  
S12294 2026.08.13       S11E14            
S12296 2026.08.14       N14E12          
S12298 2026.08.15   5 2 S14E36 0012   BXO    
Total spot count: 31 102 57  
Sunspot number: 111 202 147  (total spot count + 10 * number of spotted regions)
Weighted SN: 60 128 73  (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): 122 111 118  

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
2025.05 135.3 138.3 78.5 128.6 (-4.7) 17.26
2025.06 131.3 135.4 114.6 124.7 (-3.9) 21.43
2025.07 137.8 142.3 125.9 122.5 (-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 (99.7 projected, -4.5) 12.88
2026.03 131.0 129.7 86.6 (94.6 projected, -5.1) 15.44
2026.04  120.0 120.9 79.3 (90.7 projected, -3.9) 12.10
2026.05 125.4 128.2 101.4 (89.5 projected, -1.2) 9.80
2026.06 137.9 142.2 94.3 (87.4 projected, -2.1) 9.57
2026.07 134.7 139.0 78.1 (82.8 projected, -4.6) 10.3
2026.08 108.9 (1)   40.6 (2A) / 84.0 (2B) / 99.1 (2C) (80.6 projected, -2.2) (8.3)
2026.09       (79.7 projected, -0.9)  
2026.10       (77.7 projected, -2.0)  
2026.11       (74.8 projected, -2.9)  
2026.12       (71.6 projected, -3.2)  
2027.01       (69.3 projected, -2.3)  

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.