Solar Terrestrial Activity Report

Activity chart

Last major update issued on May 9, 2026 at 06:40 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 to active levels under the influence of effects associated with CH1363. Solar wind speed at SOHO ranged between 406 and 609 km/sec, averaging 503 km/sec (+122 km/sec compared to the previous day). The high latitude magnetometer at Andenes was at quiet to major 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 119.5 - increasing 26.2 over the previous solar rotation.

The 365 day average solar flux at 1 AU was 140.48 (183 days ago). The 81 day average solar flux at 1 AU was 125.3 (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 12 (STAR Ap - based on the average of three hour interval ap indices: 12.5). Three hour interval K indices: 21233423 (planetary), 22233333 (Boulder), 41133446 (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 11 active regions using 2K resolution (SN: 203) and in 7 active regions using 1K resolution (SN: 114) SDO/HMI images.

AR 14429 [S05W70] decayed slowly and quietly.
AR 14431 [S16W47] decayed slowly and was mostly quiet.
AR 14432 [N13W27] developed further gaining spots and area. Many low level C flares were recorded. C1 flares: C1.0 @ 11:20, C1.6 @ 16:11, C1.0 @ 17:16, C1.0 @ 17:52, C1.5 @ 18:02, C1.1 @ 18:25, C1.2 @ 19:21, C1.8 @ 20:22, C1.0 @ 22:07 UT
AR 14433 [S17E01] was mostly quiet and stable.
AR 14434 [N13W02] was quiet and stable.
AR 14435 [N22E12] was quiet and stable.

Spotted regions not observed (or interpreted differently) by SWPC/USAF:
New AR S12048 [S19W28] emerged with a tiny spot.
New AR S12049 [S33E24] emerged with a tiny spot.
New AR S12050 [S30E36] emerged with a tiny spot.
New AR S12051 [N18E80] rotated into view with a few spots. This region was the source of several recent flares while behind the northeast limb, but it is uncertain if the flare potential has changed. C1.0 @ 01:54, C1.1 @ 04:03 UT
New AR S12052 [S20E51] emerged with tiny spots.

C2+ flares

Magnitude Peak time (UT) Location Source Recorded by Comment
C4.2/1N 15:51 N12W23 14432 GOES18  
C2.1 19:07   14432 GOES18  
C2.6/2N 20:21 N12W27 14432 GOES18  
C2.4/1F 23:28 N11W31 14432 GOES18  

Coronal mass ejections (CMEs)

May 6-8: 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 trans equatorial coronal hole (CH1363) rotated across the central meridian on May 4-7. 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.

Forecast

The geomagnetic field is expected to be at quiet to active levels on May 9-13 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
14429 2026.04.29
2026.04.30
  1   S05W77 0001   AXX

was AR S12025

location: S05W70

14431 2026.04.29
2026.05.01
1 8 3 S16W48 0120 HSX CAO was AR S12026

area: 0170

location: S16W47

14432 2026.05.01
2026.05.01
18 44 27 N14W29 0140 DAI DAI

beta-gamma

area: 0290

location: N13W27

14433 2026.05.02
2026.05.03
4 19 8 S16E03 0150 CAO CAO was AR S12035

area: 0220

location: S17E01

14434 2026.05.02
2026.05.04
1 4 1 N14W04 0010 AXX BXO was AR S12036

location: N13W02

14435 2026.05.03
2026.05.04
1 9 2 N23E11 0060 HSX CSO was AR S12037

area: 0070

location: N22E12

S12040 2026.05.04       S10W15            
S12042 2026.05.04       N26W57            
S12044 2026.05.05       S08W19            
S12047 2026.05.07       S28W34          
S12048 2026.05.08   1   S19W28 0002   AXX    
S12049 2026.05.08   1 1 S33E24 0004   AXX    
S12050 2026.05.08   1   S30E36 0002   AXX    
S12051 2026.05.08   3 2 N18E80 0400   HKX    
S12052 2026.05.08   2   S20E51 0002   BXO    
Total spot count: 25 93 44  
Sunspot number: 75 203 114  (total spot count + 10 * number of spotted regions)
Weighted SN: 45 123 74  (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): 83 112 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) 12.0
2026.05  133.5 (1)   30.0 (2A) / 116.3 (2B) / 92.5 (2C) (86.4 projected, -1.2) (9.9)
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.