Solar Terrestrial Activity Report

Activity chart

Last major update issued on May 11, 2026 at 03:35 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 levels. Solar wind speed at SOHO ranged between 394 and 498 km/sec, averaging 452 km/sec (-66 km/sec compared to the previous day). The high latitude magnetometer at Andenes was at quiet 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 125.7 - increasing 27.0 over the previous solar rotation.

The 365 day average solar flux at 1 AU was 140.42 (183 days ago). The 81 day average solar flux at 1 AU was 125.6 (41 days ago, this is 35.7% 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: 3.9). Three hour interval K indices: 01111121 (planetary), 01212211 (Boulder), 10011221 (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 10 active regions using 2K resolution (SN: 180) and in 8 active regions using 1K resolution (SN: 125) SDO/HMI images.

AR 14431 [S16W74] was quiet and stable.
AR 14432 [N13W55] matured and displayed decay in the intermediate spot section. While the region continued to produce mostly low level C flares, the flare frequency was significantly lower than during the previous day. C1 flares: C1.1 @ 00:54, C1.2 @ 01:32, C1.0 @ 02:00, C1.4 @ 04:02, C1.3 @ 05:17, C1.0 @ 07:49, C1.9 @ 09:24, C1.1 @ 10:43, C1.0 @ 12:50, C1.2 @ 12:56, C1.8 @ 16:43, C1.2 @ 19:34, C1.3 @ 21:08, C1.4 @ 23:18 UT
AR 14433 [S17W24] was quiet and stable.
AR 14434 [N14W30] reemerged with a tiny spot.
AR 14435 [N23W13] was quiet and stable.
AR 14436 [N18E55] decayed slowly after the major M5.7 flare and lost the magnetic delta configuration. C1 flares: C1.6 @ 02:33, C1.4 @ 06:40 UT

Spotted regions not observed (or interpreted differently) by SWPC/USAF:
AR S12049 [S29W02] reemerged with tiny spots.
AR S12054 [N20E19] was quiet and stable.
AR S12055 [N02E11] was quiet and stable.
AR S12056 [S09W57] was quiet and stable.

C2+ flares

Magnitude Peak time (UT) Location Source Recorded by Comment
C2.1 02:40   14432 GOES18  
C2.0 05:04 N16W47 14432 GOES18  
C2.0 07:34   14432 GOES18  
C3.7 09:39   14432 GOES18  
M5.7/2B 13:39 N19E62 14436 GOES18 strong type II radio sweep, CME
C4.7 15:20   14432 GOES18  
C2.2 16:06   14432 GOES18  

Coronal mass ejections (CMEs)

May 8-9: No obviously Earth directed CMEs were observed in available coronagraph imagery.
May 10: A partial halo CME was observed after the M5 flare in AR 14436. While the main ejecta is not headed towards Earth, there is a chance of a solar wind shock on May 12 or 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 positive polarity northern hemisphere coronal hole (CH1364) was Earth facing on May 7-9. A recurrent positive polarity southern hemisphere coronal hole (CH1365) rotated across the central meridian on May 9. A recurrent negative polarity trans equatorial coronal hole (CH1366) is expected to become Earth facing on May 12-15.

Forecast

The geomagnetic field is expected to be at quiet to unsettled levels on May 11-13 due to weak effects associated with CH1364 and CH1365. There is a chance a solar wind shock related to the May 10 CME could arrive on May 12 or 13 and cause unsettled to minor storm conditions. Effects associated with CH1366 could cause quiet to minor storm conditions on May 14-17.

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
14431 2026.04.29
2026.05.01
1 1 1 S16W76 0090 HSX HAX was AR S12026

area: 0160

location: S16W74

14432 2026.05.01
2026.05.01
28 29 18 N14W56 0430 EKC EKC

beta-gamma

area: 0860

location: N13W55

14433 2026.05.02
2026.05.03
5 17 10 S17W25 0050 CAO CAO was AR S12035

area: 0100

location: S17W24

14434 2026.05.02
2026.05.04
  1 1 N14W32 0003   AXX   was AR S12036

location: N14W30

14435 2026.05.03
2026.05.04
1 4 2 N23W15 0040 HSX CSO was AR S12037

area: 0090

S12040 2026.05.04       S10W41            
S12044 2026.05.05       S08W45            
S12048 2026.05.08       S19W54            
S12049 2026.05.08   2   S29W02 0003   AXX    
S12050 2026.05.08       S30E10            
14436 2026.05.08
2026.05.09
4 11 8 N19E55 0200 DAO DSI was AR S12051

area: 0310

location: N18E55

S12052 2026.05.08       S20E25          
S12054 2026.05.09   4 2 N20E19 0006   BXO  
S12055 2026.05.09   5   N02E11 0007   BXO  
S12056 2026.05.09   6 3 S09W57 0012   BXO  
Total spot count: 39 80 45  
Sunspot number: 89 180 125  (total spot count + 10 * number of spotted regions)
Weighted SN: 69 110 75  (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): 98 99 100  

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  131.6 (1)   35.5 (2A) / 110.0 (2B) / 95.6 (2C) (86.4 projected, -1.2) (8.8)
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.

--------------------------------------------------------------------------------------

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.