Solar Terrestrial Activity Report

Activity chart

Last major update issued on May 13, 2025 at 06:40 UT. Minor update posted at 16:55 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 (May 1, 2025)
Solar cycle Solar cycles 23-25 (May 1, 2025) Historical solar and geomagnetic data charts 1954-2006 (April 5, 2007)
  Cycle 24-25 progress (May 1, 2025) 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, 2025) 3rd SSN Workshop, Tucson, 2013
  Comparison of cycles 12-14, 16, 24-25 (May 1, 2025) 4th SSN Workshop, Locarno, 2014
  Solar polar fields vs. solar cycles (April 21, 2025) Cycle 25 spots (final update December 25, 2019)
  Solar cycles 24-25 transition using 365d smoothing Research: Solar Cycle 25 Started on November 17, 2019 with 365 Days Smoothing
Calculating the Strength of Solar Cycle 25 Using 365-day Smoothing

Recent activity

The geomagnetic field was at quiet levels on May 12. Solar wind speed at SOHO ranged between 367 and 506 km/sec, averaging 423 km/sec (-18 km/sec compared to the previous day). The high latitude magnetometer at Andenes recorded 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 115.5 - decreasing 38.1 over the previous solar rotation. The 365 days average solar flux at 1 AU was 192.97 (183 days ago). SC25 peak: 195.86 on October 13, 2024 (subtracting a baseline solar flux level of 65, this is +62.6% compared to the SC24 peak and -1.7% compared to the SC23 peak). The Potsdam WDC planetary A index was 5 (STAR Ap - based on the mean of three hour interval ap indices: 5.4). Three hour interval K indices: 22112112 (planetary), 22222222 (Boulder), 22124003 (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 8 active regions using 2K resolution (SN: 132) and in 8 active regions using 1K resolution (SN: 109) SDO/HMI images.

AR 14082 [S09W50] decayed slowly and quietly.
AR 14084 [S20E09] decayed slowly and quietly.
AR 14085 [N02W03] decayed slowly and quietly.
AR 14086 [N08W68] developed slowly and produced a few C flares. C1 flares: C1.1 @ 03:53, C1.2 @ 17:01, C1.0 @ 17:23, C1.1 @ 22:22 UT
New AR 14087 [N14E78] rotated into view with a large, mature spot. C1 flares: C1.2 @ 19:48 UT

Spotted regions not observed (or interpreted differently) by SWPC/USAF:
S11054 [N08W14] developed slowly and quietly.
New region S11064 [S05W11] emerged with tiny spots.
New region S11065 [N17E84] rotated into view with two small spots that appear to form a magnetic delta configuration. C1 flares: C1.0 @ 11:59 UT

AR 14079 produced C1 flares from behind the northwest limb: C1.6 @ 00:49, C1.0 @ 01:30, C1.0 @ 02:40, C1.1 @ 04:36, C1.6 @ 05:48 UT

Minor update added at 16:55 UT: AR 14086 gained a magnetic delta early in the day and produced an X1.2 flare at 15:37 UT. This was a minor proton event as well. AR 14085 also gained a magnetic delta configuration and produced a C3.9 flare at 13:57 UT.

C2+ flares

Magnitude Peak time (UT) Location Source Recorded by Comment
C2.0 06:02 N14E87 14087 GOES19  
C2.7 13:08   14079 GOES19  
C2.7 15:02   S11065 GOES19  

Coronal mass ejections (CMEs)

May 10-11: No obviously Earth directed CMEs.
May 12: A large filament eruption across the central meridian in the northern hemisphere was observed late in the day. The associated CME was directed mostly northwards, however, there is a possibility that components of the CME could be Earth directed. In that case some CME effects will be possible on May 16.

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 northern hemisphere positive polarity coronal hole (CH1292) was Earth facing on May 7-8. A recurrent southern hemisphere negative polarity coronal hole (CH1293) rotated across the central meridian on May 11-12. A recurrent southern hemisphere negative polarity coronal hole (CH1294) will likely become Earth facing on May 15-18.

Propagation

Long distance low and medium frequency (below 2 MHz) propagation along paths north of due west over upper middle and high latitudes is poor. Propagation on long distance northeast-southwest paths is poor.

Forecast

The geomagnetic field is expected to be at quiet to unsettled levels on May 13. May 14-15 could see some unsettled and active intervals due to effects from CH1293. If components of the May 12/13 CME reaches Earth, unsettled to minors torm intervals will be possible on May 16.

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
14081 2025.05.01
2025.05.03
      N07W79        

was AR S11034

14082 2025.05.03
2025.05.04
1 3 2 S09W51 0040 HSX CSO

was AR S11040

area: 0120

location: S09W50

S11048 2025.05.06       N24W58            
14084 2025.05.07
2025.05.08
4 10 5 S20E07 0010 AXX CRO was AR S11050

location: S20E09

area: 0020

S11051 2025.05.08       N19W30          
S11053 2025.05.09       N07W33            
S11054 2025.05.09   9 5 N08W14 0020   CRO  
14086 2025.05.10
2025.05.11
6 14 8 N07W71 0030 CRO DRI beta-gamma

was AR S11055

location: N08W68

area: 0070

14085 2025.05.10
2025.05.10
2 10 4 N03W02 0030 CRO DRI beta-gamma

AR S11056

area: 0040

location: N02W03

S11060 2025.05.10       S19E01          
S11061 2025.05.10       S20W29            
14087 2025.05.12
2025.05.12
1 1 1 N15E77 0090 HSX HKX   was AR S11063

location: N14E78

area: 0360

S11064 2025.05.12   3 2 S05W11 0008   BXO    
S11065 2025.05.12   2 2 N17E84 0030   CRO   beta-delta?

interpretation is uncertain, could be part of AR 14087

Total spot count: 14 52 29  
Sunspot number: 64 132 109  (total spot count + 10 * number of spotted regions)
Weighted SN: 30 82 59  (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): 70 73 87  

Monthly solar cycle data

Month Average solar flux International sunspot number
(WDC-SILSO)
Smoothed sunspot number (4) Average ap
(3)
Measured 1 AU
2014.02 170.3
(cycle peak)
166.3 146.1 (SC24 peak) 110.5 10.70
2014.04 143.9 144.8 112.5 116.4 (SC24 solar max) 7.88
2017.09 91.3 92.3 43.6 18.2 (-1.3) 18.22
(SC24 peak)
2019.11 70.2 68.7 0.5 2.0 (-0.6)
(Solar minimum using 365d smoothing:
November 17, 2019)
4.19
2019.12 70.8 68.6 1.6 1.8 (-0.2)
(ISN 13 months smoothed
solar minimum)
3.22
2023.11 153.5 150.2 107.1 127.9 (+3.1) 12.20
2023.12 151.1 146.4 113.5 129.5 (+1.6) 9.60
2024.01 164.6 159.3 126.0 131.2 (+1.7) 5.46
2024.02 172.5 168.3 123.0 136.9 (+5.7) 5.31
2024.03 154.4 152.9 103.7 141.4 (+4.5) 11.03
2024.04 161.3 162.6 137.0 144.5 (+3.1) 9.69
2024.05 187.7 191.9 172.1 149.1 (+4.6) 23.56
(SC25 peak)
2024.06 184.3 190.2 164.1 152.8 (+3.7) 10.24
2024.07 196.6 203.0 196.8 155.0 (+2.3) 7.13
2024.08  246.1
(cycle peak)
252.2 216.0  (SC25 peak) 156.8 (+1.8) 15.96
2024.09 195.7 197.8 141.1 159.4 (+1.6) 15.36
2024.10 221.0 219.6 165.8 160.8 (+1.4) 18.99
2024.11 199.6 195.3 154.1 (159.0 projected, -1.8) 9.33
2024.12 197.3 191.2 154.6 (155.2 projected, -3.8) 8.42
2025.01 190.3 184.2 137.0 (149.7 projected, -5.5) 13.17
2025.02  184.2 179.7 154.7 (141.6 projected, -7.1) 14.42
2025.03 163.7 162.1 134.2 (135.1 projected, -6.5) 15.96
2025.04 162.5 163.6 140.6 (130.5 projected, -4.6) 17.62
2025.05  145.3 (1)   29.7 (2A) / 76.7 (2B) / 125.4 (2C) (125.2 projected, -5.3) (18.7)
2025.06       (120.3 projected, -4.9)  
2025.07       (116.1 projected, -4.2)  
2025.08       (111.4 projected, -4.7)  
2025.09       (107.1 projected, -4.3)  
2025.10       (103.2 projected, -3.9)  

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 May 13, 2025

Sunspot activity has been on a slowly decreasing trend since September 2024 (using the average solar flux over 3 solar rotations as a proxy). The decline has become more obvious during the first half of May 2025 with solar flux on May 12 at its lowest level since April 4, 2024. The solar max phase of solar cycle 25 was considerably shorter than that of the most recent solar cycles.

All 365 days smoothed sunspot numbers peaked on October 11-12, 2024
, very likely making this the peak of SC25 (STAR 1K 365d peak: 236.1, STAR 2K 365d peak: 364.3, NOAA SN 365d peak: 156.0, ISN 365d peak: 163.6). 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.