The geomagnetic field was at quiet levels. Solar wind speed at SOHO ranged between 413 and 571 km/sec, averaging 485 km/sec (-2 km/sec compared to the previous day). The high latitude magnetometer at Andenes was at quiet to unsettled 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 136.6 - increasing 32.5 over the previous solar rotation.
The 365 day average solar flux at 1 AU was 131.31 (183 days ago). The 81 day average solar flux at 1 AU was 114.2 (41 days ago, this is 28.6% 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: 22210110 (planetary), 12221220 (Boulder), 32311121 (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 6 active regions using 2K resolution (SN: 163) and in 6 active regions using 1K resolution (SN: 112) SDO/HMI images.
AR 14551 [S14W46]
developed a magnetic delta configuration in the central spot section before
noon, however, this faded and was gone by the end of the day. A major flare
is still possible. C1 flares: C1.1 @ 05:35, C1.3 @ 10:50, C1.7 @ 19:22 UT
AR 14557 [N06W13] decayed in the trailing spot section and lost spots
and area. There is still minor polarity intermixing and the chance of an M
class flare can't be ruled out. C1 flares: C1.4 @ 04:51, C1.3 @ 05:16 UT
New AR 14559 [S20W38] emerged on October 16 and was numbered by SWPC
2 days later. The region developed early in the day, then decayed slowly.
New AR 14560 [N13E13] emerged on October 17 and received its NOAA
number the next day as slow development continued.
Spotted regions not observed (or interpreted
differently) by SWPC/USAF:
New AR S12424 [N10W42] emerged with tiny spots.
New AR S12425 [N02W34] emerged with tiny spots.
C2+ flares
| Magnitude | Peak time (UT) | Location | Source | Recorded by | Comment |
| C3.4 | 03:52 | N04W00 | 14557 | GOES18 | |
| C3.7 | 06:44 | S15W33 | 14551 | GOES18 | |
| C2.1 | 19:17 | S08W38 | 14551 | GOES18 |
October 16-18: No obviously Earth directed CMEs were observed.
[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 southern hemisphere coronal hole (CH1405) rotated across the central meridian on October 16-17. A recurrent negative polarity northern hemisphere coronal hole (CH1406) will be Earth facing on October 19-20.
The geomagnetic field is expected to be at mostly quiet levels on October 19. During the latter half of the day or on October 20 a disturbance related to CH1405 is likely to start and cause unsettled to minor storm conditions lasting until October 21.
| 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.
(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 | ||||||||||
| 14551 | 2026.10.08 2026.10.09 |
12 | 33 | 15 | S16W46 | 0350 | EKI | EKI |
 |
 |
beta-gamma was AR S12407 area: 0600 location: S14W46 |
| 14553 | 2026.10.10 2026.10.11 |
N06W39 |
was AR S12413 location: N08W32 |
||||||||
| 14554 | 2026.10.11 2026.10.12 |
N07W25 |
was AR S12415 location: N08W20 |
||||||||
| 14556 | 2026.10.12 2026.10.13 |
N03W12 |
 |
was AR S12416 location: N03W04 |
|||||||
| 14557 | 2026.10.13 | 22 | 48 | 25 | N06W13 | 0140 | EAI | DAI |
 |
 |
beta-gamma split off from AR S12416 area: 0320 |
| S12419 | 2026.10.15 | S07W16 | |||||||||
| 14559 | 2026.10.16 2026.10.18 |
4 | 8 | 5 | S19W37 | 0010 | BXO | BXI |
 |
 |
beta-gamma was AR S12420 |
| S12421 | 2026.10.16 | N19W20 |
 |
||||||||
| 14560 | 2026.10.17 2026.10.18 |
4 | 8 | 4 | N14E12 | 0010 | CRO | CRO |
 |
 |
was AR S12423 area: 0030 location: N13E13 |
| S12424 | 2026.10.18 | 3 | 2 | N10W42 | 0005 | BXO |
 |
||||
| S12425 | 2026.10.18 | 3 | 1 | N02W34 | 0005 | BXO |
 |
||||
| Total spot count: | 42 | 103 | 52 | ||||||||
| Sunspot number: | 82 | 163 | 112 | (total spot count + 10 * number of spotted regions) | |||||||
| Weighted SN: | 60 | 121 | 70 | (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): | 82 | 82 | 84 | (Effective 2026.09.19: SWPC adjustment changed from 1.1 to 1.0, STAR 2K adjustment changed from 0.55 to 0.5, STAR 1K adjustment changed from 0.8 to 0.75) | |||||||
| 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 |
| 2025.07 | 137.8 | 142.3 | 125.9 | 122.5 (-2.2) | 11.80 |
| 2025.08 | 154.9 | 158.7 | 133.7 | 118.4 (-4.1) | 9.97 |
| 2025.09 | 154.4 | 156.0 | 129.7 | 113.1 (-5.3) | 14.02 |
| 2025.10 | 139.5 | 138.6 | 114.6 | 108.5 (-4.6) | 15.64 |
| 2025.11 | 140.3 | 137.3 | 91.7 | 106.9 (-1.6) | 21.01 |
| 2025.12 | 160.8 | 155.8 | 124.0 | 107.0 (-0.1) | 13.35 |
| 2026.01 | 148.7 | 144.0 | 115.0 | 104.1 (-2.9) | 22.47 |
| 2026.02 | 136.4 | 133.1 | 77.4 | 99.7 (-4.4) | 12.88 |
| 2026.03 | 131.0 | 129.7 | 86.6 | 94.4 (-5.3) | 15.44 |
| 2026.04 | 120.0 | 120.9 | 79.0 | (89.6 projected, -4.8) | 12.10 |
| 2026.05 | 125.4 | 128.2 | 101.8 | (87.1 projected, -2.5) | 9.80 |
| 2026.06 | 137.9 | 142.2 | 93.3 | (84.1 projected, -3.0) | 9.57 |
| 2026.07 | 134.7 | 139.0 | 78.1 | (79.1 projected, -5.0) | 10.16 |
| 2026.08 | 116.1 | 119.0 | 76.0 | (76.9 projected, -2.2) | 8.67 |
| 2026.09 | 105.0 | 106.1 | 60.3 | (76.0 projected, -0.9) | 7.54 |
| 2026.10 | 115.5 (1) | 45.9 (2A) / 79.1 (2B) / 75.9 (2C) | (74.0 projected, -2.0) | (12.5) | |
| 2026.11 | (71.1 projected, -2.9) | ||||
| 2026.12 | (68.0 projected, -3.1) | ||||
| 2027.01 | (65.6 projected, -2.4) | ||||
| 2027.02 | (63.8 projected, -1.8) | ||||
| 2027.03 | (62.5 projected, -1.3) | ||||
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 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.
