[Ips-dsgr] ASWFC Daily Report - 18 October 26 issued 2330 UT on 18 Oct 2026 [SEC=OFFICIAL]
Australian Space Weather Forecasting Centre
aswfc at bom.gov.au
Mon Oct 19 10:30:46 AEDT 2026
SUBJ: ASWFC DAILY SOLAR AND GEOPHYSICAL REPORT
ISSUED AT 2330UT/18 OCTOBER 2026
FROM THE AUSTRALIAN SPACE WEATHER FORECASTING CENTRE
SUMMARY FOR 18 OCTOBER AND FORECAST FOR 19 OCTOBER - 21 OCTOBER
STATUS INDICATORS SOL:** YELLOW ** MAG:** YELLOW ** ION: GREEN
ASWAS SCALE DESCRIPTION: https://bit.ly/3lmaMBx
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1A. SOLAR SUMMARY
Activity 18 Oct: R0
Flares: none.
Observed 10.7 cm flux/Equivalent Sunspot Number for 18 Oct: 137/91
1B. SOLAR FORECAST
19 Oct 20 Oct 21 Oct
Activity R0-R1 R0, chance of R1 R0, chance of R1
Fadeouts Possible None expected None expected
10.7cm/SSN 135/89 135/89 125/78
COMMENT: Solar flare activity was at the R0 level on UT day 18-Oct,
with no significant flares observed. There are currently four
active sunspot regions on the visible disk, with Active Region
(AR) 4451 (S15W46, beta-gamma) being the largest. This region
has exhibited some minor spot evolution over the previous UT
day, and has remained mostly stable. Recently numbered region
4459 (S21W41, beta) has appeared on the disk over the past 24
hours, but has started to decay. Region 4457 (N08W11, beta) has
also exhibited mild decay over the same period. A new region,
numbered 4460, has appeared at N15E15, exhibiting a beta magnetic
classification. Solar flare activity is forecast to be at the
R0-R1 level over 19-Oct, declining to R0 with a chance of R1
over 20-21 Oct as these large sunspot regions continue to show
signs of decay. S0 solar radiation storm conditions were observed
on 18-Oct, with the proton flux at background levels. S0 solar
radiation storm conditions are forecast over 19-21 Oct. No geoeffective
coronal mass ejections were observed over the previous UT day
in available coronagraph imagery. A large filament centred on
N05W50 has shown signs of evolution over the previous UT day,
which will continue to be monitored. The solar wind environment
trended toward ambient conditions over UT day 18-Oct. The solar
wind speed began the UT day at 500-520 km/s, declining to range
between 400 and 420 km/s over the past 6 hours. The interplanetary
magnetic field strength (IMF, Bt) was largely stable throughout
the UT day, peaking at 7 nT, with the north-south component (Bz)
ranging between -5 and +5 nT. The solar wind speed is forecast
to continue to trend toward ambient conditions over most of 19-Oct,
before rising late in the UT day due to Earth's connection to
a coronal hole high speed wind stream. The solar wind speed is
expected to continue to rise over 20-Oct due to this high speed
wind stream, and remain elevated on 21-Oct.
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2A. MAGNETIC SUMMARY
Geomagnetic field for Australian Region 18 Oct: G0
Estimated Indices 18 Oct : A K
Australian Region 4 22111211
Cocos Island 2 11101210
Darwin 4 22111211
Townsville 4 22111211
Learmonth 6 22211311
Alice Springs 5 22111311
Gingin 6 22211321
Canberra 3 12120210
Kennaook Cape Grim 4 12121210
Hobart 4 12121210
Estimated Antarctic Regional K Indices 18 Oct :
Casey 19 55331322
Mawson 11 33321332
Observed Regional daily pc3 Indices 18 Oct :
Darwin 0 (Quiet)
Townsville 0 (Quiet)
Learmonth 0 (Quiet)
Alice Springs 0 (Quiet)
Gingin 13 (Quiet)
Canberra 28 (Quiet to unsettled)
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 18 Oct : A
Fredericksburg 6
Planetary 6
Observed AFr/Ap Indices 17 Oct : A K
Fredericksburg 4
Planetary 6 2111 1331
2B. MAGNETIC FORECAST
Date Ap Conditions
19 Oct 12 G0
20 Oct 18 G0, chance of G1
21 Oct 12 G0
COMMENT: Geomagnetic conditions in the Australian region were
at the G0 level on UT day 18-Oct, with G0 conditions also recorded
at the planetary scale. Mostly G0 conditions were observed in
the Antarctic region, with G1 intervals observed at Mawson. G0
conditions are forecast on 19-21 Oct, with a chance of G1 on
20-Oct due to high speed wind stream effects from an equatorial
coronal hole.
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3A. GLOBAL HF PROPAGATION SUMMARY
Latitude Band
Date Low Middle High
18 Oct Normal Normal-fair Fair
PCA Event : No event.
3B. GLOBAL HF PROPAGATION FORECAST
Latitude Band
Date Low Middle High
19 Oct Normal Normal Normal
20 Oct Normal Normal Normal-fair
21 Oct Normal Normal Normal
COMMENT: Global high-frequency (HF) radio propagation conditions
were normal to fair on UT day 18-Oct, with fair conditions observed
in high latitude regions during local night. Some degradations
were also observed at the start of the UT in the Australian region,
and at local dusk in mid-latitude Asian and European locations.
Global HF propagation conditions are forecast to be mostly normal
over 19-21 Oct, with some degradations in high latitude regions
on 20-Oct due to forecast geomagnetic activity. Shortwave fadeouts
are possible.
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4A. AUSTRALIAN REGION IONOSPHERIC SUMMARY
Date T index
18 Oct 45
Observed Australian Regional MUFs
Cocos Island Region:
No data available during local day.
No data available during local night.
Niue Island Region:
Enhanced by 15% during local day.
Near predicted monthly values during local night.
Northern Australian Region:
Mostly near predicted monthly values.
Southern Australian Region:
Near predicted monthly values during local day.
Depressed by 15% during local night.
Antarctic Region (Casey/Davis/Mawson):
Near predicted monthly values over the UT day.
Monthly T index:
Month T index
Sep 61
Oct 60
Nov 58
4B. AUSTRALIAN REGION IONOSPHERIC FORECAST
Date T index MUFs
19 Oct 50 Near predicted monthly values
20 Oct 45 Near predicted monthly values
21 Oct 50 Near predicted monthly values
COMMENT: ASWFC SWF HF Communications Warning 89 was issued on
17 October and is current for 18-19 Oct. Maximum Usable Frequencies
(MUFs) in the Australian region were mostly near predicted values
on 18-Oct, with some depressions observed in the southern Australian
region at the beginning of the UT day. Sporadic E was observed
in the northern Australian region during local night hours, with
spread F observed at Hobart and Canberra during local night hours.
MUFs are forecast to be near predicted values over 19-21 Oct,
with some mild depressions possible on 20-Oct due to forecast
geomagnetic activity. Shortwave fadeouts are possible.
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5. SPACE ENVIRONMENT SUMMARY
GOES satellite data for 17 Oct
Daily Proton Fluence >1 MeV: 2.6E+05
Daily Proton Fluence >10 MeV: 2.1E+04
Daily Electron Fluence >2 MeV: 2.50E+07 (normal fluence)
Electron Fluence Daily Deep Dielectric Discharge Probability: 4%
Fluence (flux accumulation over 24hrs)/ cm2-ster-day.
X-ray background: B6.0
Solar Wind Day Averaged Data for 17 Oct
Speed: 454 km/sec Density: 4.4 p/cc Temp: 123000 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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