Solar Terrestrial Activity Report

Activity chart

Last major update issued on May 15, 2025 at 04:05 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 to active levels on May 14, probably under the influence of effects from CH1293. Solar wind speed at SOHO ranged between 383 and 473 km/sec, averaging 425 km/sec (+18 km/sec compared to the previous day). The high latitude magnetometer at Andenes recorded quiet to minor storm levels. The above 10 MeV proton flux returned to background levels late in the day.

Solar flux density measured at 20h UT on 2.8 GHz was 121.8 - decreasing 28.9 over the previous solar rotation. The 365 days average solar flux at 1 AU was 192.42 (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 15 (STAR Ap - based on the mean of three hour interval ap indices: 15.4). Three hour interval K indices: 42234342 (planetary), 33224432 (Boulder), 52235343 (Andenes).

The background x-ray flux is at the class B5 level (GOES 19).

At the time of counting spots (see image time), spots were observed in 12 active regions using 2K resolution (SN: 177) and in 8 active regions using 1K resolution (SN: 104) SDO/HMI images.

AR 14082 [S09W77] decayed slowly and quietly.
AR 14084 [S21W16] decayed slowly and quietly.
AR 14085 [N03W29] decayed slowly and quietly.
AR 14087 [N14E64] gained tiny spots and was mostly quiet.
New AR 14088 [N09W41] emerged on May 9 and was noticed by SWPC 5 days later as slow development continued.

Spotted regions not observed (or interpreted differently) by SWPC/USAF:
S11060 [S18W23] reemerged with tiny spots.
S11065 [N17E57] still has a very tight magnetic delta configuration in the main penumbra, however some area was lost after all the M and X flares. Another major flare is possible. C1 flares: C1.8 @ 17:53 UT
S11067 [S02E33] was quiet and stable.
New region S11068 [N30E37] emerged near noon with tiny spots.
New region S11069 [S17E35] was observed with tiny spots in an old plage area.
New region S11070 [N08E57] was observed with tiny spots in an old plage area.
New region S11071 [N15W17] was observed with tiny spots in an old plage area.

An active region behind the northeast limb was the source of a C1.2 flare at 01:57 UT. A C1.3 flare at 15:04 UT likely had its origin behind the southeast limb. A C1.6 flare at 16:51 UT most likely had its origin either behind the northeast or the southeast limb.

C2+ flares

Magnitude Peak time (UT) Location Source Recorded by Comment
C2.1 02:15   S11065 GOES19  
M5.3 03:25 N17E69 (SDO/AIA) S11065 GOES19 moderate type II radio sweep
C5.5 07:20 N17E66 (SDO/AIA) S11065 GOES19  
M1.2 07:45 N17E90 (behind northeast limb)   GOES19  
X2.7/2B 08:18 N17E65 (SDO/AIA) S11065 GOES19  
M7.7/1N 11:18 N18E64 (SDO/AIA) S11065 GOES19  
C2.4 14:27 N17E61 (SDO/AIA) S11065 GOES19  
M4.7 18:11   S11065 GOES19  

Coronal mass ejections (CMEs)

May 13-14: 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 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 active levels on May 15 due to effects from CH1293. If components of the May 12/13 CME reach Earth, unsettled to minor storm intervals will be possible on May 16-17.

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
14082 2025.05.03
2025.05.04
1 2 1 S09W78 0040 HSX HAX

was AR S11040

area: 0100

location: S09W77

14084 2025.05.07
2025.05.08
  4 1 S20W21 0010   BXO was AR S11050

location: S21W16

S11051 2025.05.08       N19W56            
S11053 2025.05.09       N07W59            
14088 2025.05.09
2025.05.14
5 18 8 N09W41 0010 BXO DRI was AR S11054

area: 0050

14085 2025.05.10
2025.05.10
2 1   N03W30 0010 BXO AXX

AR S11056

area: 0002

location: N03W29

S11060 2025.05.10   2 1 S18W23 0005   AXX    
S11061 2025.05.10       S20W55            
14087 2025.05.12
2025.05.12
5 12 6 N15E52 0200 DSO CHI was AR S11063

location: N14E50

area: 0390

SWPC includes AR S11065 in this AR

S11064 2025.05.12       S05W37            
S11065 2025.05.12   5 5 N17E57 0130   DAC beta-delta
S11066 2025.05.13       N04W19          
S11067 2025.05.13   6   S02E33 0010   BXO  
S11068 2025.05.14   2   N30E37 0004   BXO    
S11069 2025.05.14   2 1 S17E35 0006   AXX    
S11070 2025.05.14   1   N08E57 0001   AXX    
S11071 2025.05.14   2 1 N15W17 0006   AXX    
Total spot count: 13 57 24  
Sunspot number: 53 177 104  (total spot count + 10 * number of spotted regions)
Weighted SN: 23 80 47  (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): 58 97 83  

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  141.6 (1)   33.1 (2A) / 73.4 (2B) / 123.2 (2C) (125.2 projected, -5.3) (17.7)
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.

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

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.