Solar Terrestrial Activity Report

Activity chart

Last major update issued on January 17, 2026 at 07:15 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 (January 1, 2026)
Solar cycle Solar cycles 23-25 (January 1, 2026) Historical solar and geomagnetic data charts 1954-2006 (April 5, 2007)
  Cycle 24-25 progress (January 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 (January 1, 2026) 3rd SSN Workshop, Tucson, 2013
  Comparison of cycles 12-14, 16, 24-25 (January 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 unsettled to minor storm levels on January 16, after 10h UT under the influence of effects associated with CH1340. The phi angle has been in a positive sector since after 14h UT. Solar wind speed at SOHO ranged between 533 and 752 km/sec, averaging 660 km/sec (+91 km/sec compared to the previous day). The above 10 MeV proton flux was at background levels all day.

Solar flux density measured at 20h UT on 2.8 GHz was 147.5 - increasing 23.6 over the previous solar rotation.

The 365 day average solar flux at 1 AU was 152.47 (183 days ago). The 81 day average solar flux at 1 AU was 142.7 (41 days ago, this is 46.5% 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 26 (STAR Ap - based on the average of three hour interval ap indices: 26.4). Three hour interval K indices: 34333545 (planetary), 33334533 (Boulder), 54434666 (Andenes).

The background x-ray flux is at the class C1 level (GOES 19).

At the time of counting spots (see image time), spots were observed in 11 active regions using 2K resolution (SN: 232) and in 10 active regions using 1K resolution (SN: 166) SDO/HMI images.

AR 14336 [S09W83] was quiet and stable.
AR 14340 [N14W22] decayed further and was quiet.
AR 14341 [S09E45] gained area and has minor polarity intermixing. A major flare is still possible. C1 flares: C1.1 @ 04:04, C1.3 @ 04:59, C1.2 @ 05:14, C1.0 @ 11:00, C1.3 @ 13:26, C1.2 @ 13:57, C1.0 @ 16:53, C1.4 @ 17:21, C1.4 @ 18:53, C1.6 @ 20:22, C1.6 @ 21:04, C1.5 @ 21:38 UT
AR 14342 [N17E48] decayed slowly and was mostly quiet.
AR 14343 [S11W04] developed further and has major flare potential. C1 flares: C1.4 @ 01:39, C1.2 @ 05:23, C1.1 @ 11:16, C1.3 @ 11:41, C1.3 @ 12:00, C1.3 @ 12:12, C1.4 @ 12:19, C1.2 @ 14:36, C1.7 @ 16:02, C1.4 @ 17:21, C1.9 @ 20:43, C1.4 @ 21:59, C1.2 @ 22:31, C1.7 00:01 (flare began at 23:54) UT
AR 14344 [N19E38] decayed slowly and was mostly quiet. C1 flares: C1.5 @ 03:03, C1.0 @ 06:41 UT
AR 14345 [S17E51] developed early in the day, then decayed slowly after noon.
AR 14346 [S14E62] was quiet and stable.
New AR 14347 [N11E74] rotated into view with a mature spot.

Spotted regions not observed (or interpreted differently) by SWPC/USAF:
AR S11780 [N13E51] was quiet and stable.
New AR S11783 [N02E55] emerged with a tiny spot.

C2+ flares

Magnitude Peak time (UT) Location Source Recorded by Comment
C6.6 09:09 S18E59 14345 GOES18  
C3.0 09:31   14345 GOES18  
C2.0 12:40 behind southeast limb   GOES18 simultaneous flare in AR 14343
C2.6 19:11   14343 GOES18  
C4.0 19:15 S10W04 14343 GOES18  
C3.0 23:05   14343 GOES18  
C5.2 23:10   14343 GOES18  
C2.8 23:30   14342 GOES18  

Coronal mass ejections (CMEs)

January 14-16: 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 huge recurrent trans equatorial positive polarity coronal hole (CH1340) will be Earth facing on January 15-18.

Forecast

The geomagnetic field is expected to be at quiet to minor storm levels on January 17-21 due to effects associated with CH1340.

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
14336 2026.01.04
2026.01.04
1 2 1 S09W87 0170 HSX CHO

was AR S11747

area: 0300

location: S09W83

14338 2026.01.06
2026.01.08
      S06W84           was AR S11754

location: S05W70

14340 2026.01.10
2026.01.11
10 8 3 N24W21 0050 CAO CRO

was AR S11760

area: 0020

location: N14W22

SWPC data does not reflect physical reality

S11761 2026.01.10       N16W21           merged with AR S11760
S11764 2026.01.11       S15W22            
S11766 2026.01.12       N27W34            
S11767 2026.01.12       N08W47            
S11769 2026.01.13       N11E09            
14341 2026.01.13
2026.01.14
16 47 24 S11E42 0840 DKC DKC beta-gamma

was AR S11770

area: 1290

location: S09E45

14342 2026.01.14
2026.01.14
2 7 4 N17E49 0180 DSO CSO was AR S11772

area: 0230

location: N17E48

S11773 2026.01.14       N17W01          
14343 2026.01.14
2026.01.15
18 34 22 S11W09 0310 DKI DKC beta-gamma

was AR S11774

area: 0500

location: S11W04

14344 2026.01.15 1 6 2 N19E36 0010 AXX HRX area: 0015

location: N19E38

14345 2026.01.15
2026.01.15
4 9 6 S17E49 0020 CAO DRI beta-gamma

was AR S11776

area: 0050

location: S17E51

14346 2026.01.15
2026.01.15
1 4 1 S14E61 0010 HRX CRO was AR S11777

area: 0030

location: S14E62

S11778 2026.01.15       N19W28          
S11779 2026.01.15       N12E31          
S11780 2026.01.15   3 2 N13E51 0007   BXO  
14347 2026.01.16
2026.01.16
1 1 1 N11E70 0060 HSX HSX   was AR S11781

area: 0140

location: N11E74

S11783 2026.01.16   1   N02E55 0001   AXX    
Total spot count: 54 122 66  
Sunspot number: 144 232 166  (total spot count + 10 * number of spotted regions)
Weighted SN: 102 179 133  (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): 158 128 133  

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
2024.11 199.6 195.3 154.1 157.2 (-3.7) 9.33
2024.12 197.3 191.2 154.6 151.2 (-6.0) 8.42
2025.01 190.3 184.2 137.0 146.2 (-5.0) 13.17
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 78.5 128.5 (-4.8) 17.26
2025.06 131.3 135.4 114.6 124.7 (-3.8) 21.43
2025.07 137.8 142.3 125.6 (122.4 projected, -2.3) 11.80
2025.08 154.9 158.7 133.5 (119.3 projected, -3.1) 9.97
2025.09 154.4 156.0 129.8 (115.8 projected, -3.5) 14.02
2025.10 139.5 138.6 114.6 (111.8 projected, -4.0) 15.64
2025.11 140.3 137.3 91.7 (109.5 projected, -2.3) 21.01
2025.12 160.8 155.8 124.0 (108.0 projected, -1.5) 13.35
2026.01 138.0 (1)   50.0 (2A) / 96.8 (2B) / 123.2 (2C) (104.0 projected, -4.0) (14.2)
2026.02       (99.9 projected, -4.1)  
2026.03       (95.5 projected, -4.4)  
2026.04       (91.8 projected, -3.7)  
2026.05       (90.5 projected, -1.3)  
2026.06       (88.4 projected, -2.1)  

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 October 2025

Sunspot activity was on a decreasing trend from September 2024 until mid August 2025 (using the average solar flux over 3 solar rotations as a proxy). Then a strong surge in activity saw solar flux peak in late August 2025 just below the largest peaks seen in 2024. A slow decrease in activity from the August level has been observed in September and October 2025.

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.