Solar Terrestrial Activity Report

Activity chart

Last major update issued on June 16, 2026 at 07:55 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 (June 1, 2026)
Solar cycle Solar cycles 23-25 (June 1, 2026) Historical solar and geomagnetic data charts 1954-2006 (April 5, 2007)
  Cycle 24-25 progress (June 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 (June 1, 2026) 3rd SSN Workshop, Tucson, 2013
  Comparison of cycles 12-14, 16, 24-25 (June 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. Solar wind speed at SOHO ranged between 379 and 475 km/sec, averaging 426 km/sec (-57 km/sec compared to the previous day). A weak disturbance was observed beginning early on June 16 at ACE, possibly related to the arrival of effects from CH1374 as the phi angle has remained in a negative sector. The high latitude magnetometer at Andenes was at quiet to active 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 117.0 - increasing 11.3 over the previous solar rotation.

The 365 day average solar flux at 1 AU was 139.95 (183 days ago). The 81 day average solar flux at 1 AU was 128.5 (41 days ago, this is 37.6% 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: 4.1). Three hour interval K indices: 21111012 (planetary), 21122222 (Boulder), 42111132 (Andenes).

The background x-ray flux is at the class B4 level (GOES 19).

At the time of counting spots (see image time), spots were observed in 9 active regions using 2K resolution (SN: 153) and in 7 active regions using 1K resolution (SN: 101) SDO/HMI images.

AR 14463 [N17W67] decayed slowly and quietly.
AR 14464 [S13W73] was mostly quiet and stable. C1 flares: C1.7 @ 02:13, C1.0 @ 04:19 UT.
AR 14465 [N07W22] still has a tiny magnetic delta configuration within the main penumbra. An M class flare is possible. C1 flares: C1.3 @ 08:59, C1.8 @ 13:15 UT
AR 14468 [N10E39] decayed slowly and quietly.
New AR 14469 [S16E22] was first observed with spots on June 10 and was numbered by SWPC 5 days later when new flux emerged. The region decayed slowly after noon.

Spotted regions not observed (or interpreted differently) by SWPC/USAF:
AR S12141 [S04E35] was quiet and stable.
AR S12143 [N10W27] decayed slowly and quietly.
New AR S12149 [N07E82] rotated into view with a few spots. C1 flares: C1.7 @ 09:56, C1.4 @ 11:52, C1.9 @ 18:51, C1.1 @ 00:03 (on June 16, flare began before midnight) UT
New AR S12150 [S01E04] emerged with a tiny spot.

C2+ flares

Magnitude Peak time (UT) Location Source Recorded by Comment

Coronal mass ejections (CMEs)

June 13-15: 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 negative polarity northern hemisphere coronal hole (CH1374) was Earth facing on June 13. A positive polarity southern hemisphere coronal hole (CH1375) rotated across the central meridian on June 13. An elongated trans equatorial positive polarity coronal hole (CH1376) will be Earth facing on June 15-18.

Forecast

The geomagnetic field is expected to be at quiet to unsettled levels on June 16-18 due to effects associated with CH1374 and CH1375.

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
14463 2026.06.04
2026.06.05
1 1 1 N17W68 0030 HSX HSX was AR S12117

location: N17W67

14464 2026.06.04
2026.06.06
2 3 2 S14W70 0100 HSX CSO was AR S12120

area: 0200

location: S13W73

14465 2026.06.07
2026.06.08
19 23 13 N08W24 0180 DAI DAC beta-gamma-delta

was AR S12125

area: 0250

location: N07W22

S12131 2026.06.09       S04W14          
S12133 2026.06.10       N11W54            
14469 2026.06.10 3 12 6 S16E20 0010 BXO CRI was AR S12134

area: 0040

location: S16E22

S12135 2026.06.10       S17W57            
14468 2026.06.13
2026.06.14
3 7 3 N11E25 0010 BXO CRO was AR S12138

area: 0015

location: N10E26

S12139 2026.06.13       N21W02            
S12141 2026.06.13   6   S04E35 0007   BXO  
S12142 2026.06.13       S17W22            
S12143 2026.06.14   7 3 N10W27 0013   CRO  
S12144 2026.06.14       N18E52          
S12145 2026.06.14       N05E26          
S12146 2026.06.14       S27E13          
S12147 2026.06.14       N17E66          
S12148 2026.06.14       S14E41          
S12149 2026.06.15   3 3 N07E82 0070   DAO    
S12150 2026.06.15   1   S01E04 0001   AXX    
Total spot count: 28 63 31  
Sunspot number: 78 153 101  (total spot count + 10 * number of spotted regions)
Weighted SN: 43 92 60  (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): 86 84 81  

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
2025.03 163.7 162.1 134.2 135.9 (-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 91.7 106.7 (-1.6) 21.01
2025.12 160.8 155.8 124.0 (106.4 projected, -0.3) 13.35
2026.01 148.7 144.0 112.6 (102.7 projected, -3.7) 22.47
2026.02 136.4 133.1 78.2 (98.5 projected, -4.2) 12.88
2026.03 131.0 129.7 85.9 (93.9 projected, -4.6) 15.44
2026.04  120.0 120.9 79.3 (90.0 projected, -3.9) 12.10
2026.05 125.4 128.2 101.4 (88.7 projected, -1.3) 9.80
2026.06 132.1 (1)   55.7 (2A) / 111.5 (2B) / 124.6 (2C) (86.6 projected, -2.1) (11.2)
2026.07       (82.2 projected, -4.4)  
2026.08       (80.1 projected, -2.1)  
2026.09       (79.1 projected, -1.0)  
2026.10       (77.1 projected, -2.0)  
2026.11       (74.3 projected, -2.8)  

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.