[Ips-dsgr] ASWFC Daily Report - 25 September 26 issued 2330 UT on 25 Sep 2026 [SEC=OFFICIAL]
Australian Space Weather Forecasting Centre
aswfc at bom.gov.au
Sat Sep 26 09:30:58 AEST 2026
SUBJ: ASWFC DAILY SOLAR AND GEOPHYSICAL REPORT
ISSUED AT 2330UT/25 SEPTEMBER 2026
FROM THE AUSTRALIAN SPACE WEATHER FORECASTING CENTRE
SUMMARY FOR 25 SEPTEMBER AND FORECAST FOR 26 SEPTEMBER - 28 SEPTEMBER
STATUS INDICATORS SOL:GREEN MAG:GREEN ION: GREEN
ASWAS SCALE DESCRIPTION: https://bit.ly/3lmaMBx
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1A. SOLAR SUMMARY
Activity 25 Sep: R0
Flares: none.
Observed 10.7 cm flux/Equivalent Sunspot Number for 25 Sep: 105/54
1B. SOLAR FORECAST
26 Sep 27 Sep 28 Sep
Activity R0 R0 R0
Fadeouts None expected None expected None expected
10.7cm/SSN 100/48 95/41 95/41
COMMENT: Solar flare activity on UT day 25-Sep was at the R0
level, with only low-level C-class flares observed. There are
currently eight numbered sunspot regions and one unnumbered region
visible on the solar disk. Active region (AR) 4536 (N03W52, beta-gamma)
is currently the largest region and has seen some mild decay
over the past UT day. The unnumbered region (S09W41, beta) has
shown some east-west separation over the UT day. All other sunspot
regions are either stable or in decay. Solar flare activity is
expected to be at the R0 level over 26-28 Sep. Solar radiation
storm conditions were at the S0 level on 25-Sep, with the solar
proton flux at background levels. S0 solar radiation storm conditions
are forecast over 26-28 Sep. No Earth-directed coronal mass ejections
(CMEs) were observed over the past UT day. The solar wind speed
on UT day 25-Sep was largely stable over the day, increasing
slightly before decreasing again in the latter half of the day.
Speeds ranged from 400 to 550 km/s, and is currently near 490
km/s. The peak total interplanetary magnetic field strength (IMF,
Bt) was 10 nT. The north-south component (Bz) ranged between
-10 and +7 nT over the same period. Sustained periods of southward
IMF were observed over most of the UT day. The solar wind speed
is expected to remain elevated over 26-28 Sep due to ongoing
coronal hole high speed wind stream effects from a southern coronal
hole before entering another high speed wind stream from a northern
hemisphere coronal hole over 26-Sep.
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2A. MAGNETIC SUMMARY
Geomagnetic field for Australian Region 25 Sep: GO
Estimated Indices 25 Sep : A K
Australian Region 12 22334223
Cocos Island 9 22223232
Darwin 11 22333223
Townsville 12 22343223
Learmonth 14 33334322
Alice Springs 11 22333223
Gingin 18 32335333
Canberra 12 22343223
Kennaook Cape Grim 14 22344223
Hobart 17 23354223
Estimated Antarctic Regional K Indices 25 Sep :
Casey 15 34432223
Mawson 55 55544467
Observed Regional daily pc3 Indices 25 Sep :
Darwin 0 (Quiet)
Townsville 0 (Quiet)
Learmonth 0 (Quiet)
Alice Springs 0 (Quiet)
Gingin 14 (Quiet)
Canberra 18 (Quiet)
Pc3 pulsations are high frequency (10-45 second period) variations
of the Earths magnetic field. Daily pc3-indices are the daily sum
of 20 minute pc3-indices for that station and have been shown to be
well correlated with rejection of high resolution aeromagnetic
survey flight-line data.
NOTE: Indices may have been generated from data obtained in
cooperation with the following organisations: Geoscience Australia,
University of Newcastle Space Physics Group, Australian Government
Antarctic Division and International Center for Space Weather
Science and Education, Japan.
Estimated AFr/Ap Indices 25 Sep : A
Fredericksburg 14
Planetary 20
Observed AFr/Ap Indices 24 Sep : A K
Fredericksburg 13
Planetary 16 3234 4323
2B. MAGNETIC FORECAST
Date Ap Conditions
26 Sep 12 G0, chance G1
27 Sep 12 G0, chance G1
28 Sep 9 G0
COMMENT: Elevated geomagnetic conditions were observed in Australia.
A period of G1 was observed in Hobart and Gingin, with G0 geomagnetic
conditions observed otherwise. Three periods of G1 geomagnetic
conditions were observed in the Antarctic region at Mawson, with
a single period of G2 and a period of G3 also observed at Mawson.
Planetary geomagnetic conditions were at G0. G0 geomagnetic conditions
are expected over 26-28 Sep, with chance of G1 on 26-27 Sep due
to a northern hemisphere coronal hole.
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3A. GLOBAL HF PROPAGATION SUMMARY
Latitude Band
Date Low Middle High
25 Sep Normal Normal Normal-fair
PCA Event : No event.
3B. GLOBAL HF PROPAGATION FORECAST
Latitude Band
Date Low Middle High
26 Sep Normal Normal Normal-fair
27 Sep Normal Normal Normal-fair
28 Sep Normal Normal Normal-fair
COMMENT: Global high-frequency (HF) radio propagation conditions
on the 25-Sep was mostly normal, with some normal-fair conditions
observed in high latitude regions. Global HF conditions are expected
to be mostly normal over 26-28 Sep with a continuation of normal-fair
conditions at high latitudes due to further anticipated geomagnetic
activity.
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4A. AUSTRALIAN REGION IONOSPHERIC SUMMARY
Date T index
25 Sep 64
Observed Australian Regional MUFs
Cocos Island Region:
No data available during local day.
No data available during local night.
Niue Island Region:
Enhanced by 30% during local day.
Enhanced by 30% during local night.
Enhanced by 25% after local dawn.
Northern Australian Region:
Near predicted monthly values during local day.
Enhanced by 15% during local night.
Southern Australian Region:
Near predicted monthly values.
Antarctic Region (Casey/Davis/Mawson):
Depressed by 15% over the UT day.
Monthly T index:
Month T index
Aug 66
Sep 62
Oct 60
4B. AUSTRALIAN REGION IONOSPHERIC FORECAST
Date T index MUFs
26 Sep 60 Near predicted monthly values
27 Sep 65 Near predicted monthly values
28 Sep 65 Near predicted monthly values
COMMENT: Maximum Usable Frequencies (MUFs) in the Australian
region were mostly near predicted monthly values over UT day
25-Sep with enhancements of up to 15% during local night in the
Northern Australian region. Canberra experienced a period of
sporadic-E from 0800-1200 UTC. MUFs are forecast to be near predicted
monthly values over 26-28 Sep. While depressions are expected
due to further anticipated geomagnetic activity, current MUFs
are already elevated above predicted monthly values.
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5. SPACE ENVIRONMENT SUMMARY
GOES satellite data for 24 Sep
Daily Proton Fluence >1 MeV: 7.0E+05
Daily Proton Fluence >10 MeV: 2.1E+04
Daily Electron Fluence >2 MeV: 1.40E+07 (normal fluence)
Electron Fluence Daily Deep Dielectric Discharge Probability: 3%
Fluence (flux accumulation over 24hrs)/ cm2-ster-day.
X-ray background: B4.3
Solar Wind Day Averaged Data for 24 Sep
Speed: 378 km/sec Density: 8.0 p/cc Temp: 135000 K Bz: -2 nT
(Courtesy Space Weather Prediction Center, Boulder USA)
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Australian Space Weather Forecasting Centre
Bureau of Meteorology
ASWFC at bom.gov.au
www.bom.gov.au | www.sws.bom.gov.au
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