Solar Terrestrial Activity Report

Activity chart

Last major update issued on May 15, 2026 at 05:30 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 unsettled levels, weakly under the decreasing influence of effects associated with CH1365. Solar wind speed at SOHO ranged between 378 and 485 km/sec, averaging 436 km/sec (-4 km/sec compared to the previous day). The high latitude magnetometer at Andenes was at quiet to minor 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 106.4 - decreasing 0.7 over the previous solar rotation.

The 365 day average solar flux at 1 AU was 140.30 (183 days ago). The 81 day average solar flux at 1 AU was 125.6 (41 days ago, this is 35.8% 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: 4.8). Three hour interval K indices: 31111111 (planetary), 31212211 (Boulder), 53112114 (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 5 active regions using 2K resolution (SN: 92) and in 4 active regions using 1K resolution (SN: 62) SDO/HMI images.

AR 14435 [N21W65] developed early in the day, however, signs of decay became obvious during the latter half of the day. Many C flares were recorded until 18h UT. C1 flares: C1.0 @ 01:00, C1.9 @ 05:37, C1.6 @ 06:04, C1.0 @ 06:33, C1.3 @ 07:36, C1.3 @ 07:44, C1.1 @ 08:02, C1.2 @ 08:55, C1.7 @ 09:29, C1.5 @ 10:42, C1.5 @ 12:03, C1.3 @ 14:33 UT
AR 14436 [N18E02] decayed slowly and was mostly quiet.
AR 14438 [N19W41] developed and produced low level C flares late in the day. C1 flares: C1.0 @ 22:03, C1.5 @ 22:20, C1.1 @ 23:06, C1.2 @ 23:21, C1.6 @ 00:10 (flare started at 23:47) UT

Spotted regions not observed (or interpreted differently) by SWPC/USAF:
AR S12063 [N15E12] was quiet and stable.
New AR S12066 [S17E21] emerged with tiny spots.

AR 14432 produced C1 flares from behind the northwest limb: C1.6 @ 02:12, C1.3 @ 12:16, C1.0 @ 13:40 UT

C2+ flares

Magnitude Peak time (UT) Location Source Recorded by Comment
C2.5 03:36   14438 GOES18  
C2.6 03:41   14435 GOES18  
C5.5 06:42 N21W57 14435 GOES18  
C2.2 07:09   14435 GOES18  
C2.5 09:20   14435 GOES18  
C2.0 10:51   14435 GOES18  
C2.5 10:56 N22W60 14435 GOES18  
C2.3 11:03   14435 GOES18  
C3.8 11:36 N21W61 14435 GOES18  
C2.9 11:41 behind NW limb 14432 GOES18  
C2.4 17:13   14435 GOES18  
C4.4 17:39 behind NW limb 14432 GOES18 LDE
C5.1 18:40 N17E08 14436 GOES18 LDE

Coronal mass ejections (CMEs)

May 12-14: 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 trans equatorial coronal hole (CH1366) will be Earth facing on May 12-15.

Forecast

The geomagnetic field is expected to be at quiet to major storm levels on May 15-17 under the influence of a high speed stream associated with CH1366.

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
14433 2026.05.02
2026.05.03
1     S17W80 0010 AXX     was AR S12035

spotless

location: S17W78

14434 2026.05.02
2026.05.04
      N14W88           was AR S12036

location: N14W82

14435 2026.05.03
2026.05.04
7 8 5 N22W66 0050 DRI DAO was AR S12037

area: 0090

location: N21W65

S12049 2026.05.08       S29W54            
S12050 2026.05.08       S30W42            
14436 2026.05.08
2026.05.09
7 16 10 N18E02 0180 CAO CAO

was AR S12051

area: 0240

S12052 2026.05.08       S22W39          
S12054 2026.05.09       N20W33            
S12055 2026.05.09       N02W41            
S12057 2026.05.11       S18W54            
14438 2026.05.12
2026.05.13
5 9 5 N20W44 0050 DAO DAO was AR S12058

area: 0100

location: N19W41

S12060 2026.05.12       S06W04            
S12061 2026.05.12       N08W45            
S12063 2026.05.13   6 2 N15E12 0012   BXO  
S12064 2026.05.13       N25W23          
S12065 2026.05.13       S14E35          
S12066 2026.05.14   3   S17E21 0004   AXX    
Total spot count: 20 42 22  
Sunspot number: 60 92 62  (total spot count + 10 * number of spotted regions)
Weighted SN: 33 57 37  (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): 66 51 50  

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  125.2 (1)   43.6 (2A) / 96.6 (2B) / 95.7 (2C) (86.4 projected, -1.2) (7.8)
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.