[Ips-dhfpr] ASWFC Daily HF Prop Report - 31 December 25 issued 2330 UT on 31 Dec 2025 [SEC=OFFICIAL]

[Australian Space Weather Forecasting Centre]

SUBJ: ASWFC DAILY HF PROPAGATION REPORT
ISSUED AT 2330UT/31 DECEMBER 2025
FROM THE AUSTRALIAN SPACE WEATHER FORECAST CENTRE
AUSTRALIAN REGION SUMMARY AND FORECAST

1. SUMMARY (31 DECEMBER) 
Date   T index  Conditions    
31 Dec   138    Normal         

Flares    Max     Fadeout    Freq.  Sectors
  M7.1    1351UT  probable   lower  European

MUFs:
   Cocos Island Region:
      No data.
   Niue Island Region:
      Mostly near predicted monthly values.
      Enhanced by 20% after local dawn.
   Northern Australian Region:
      Near predicted monthly values during local day.
      Enhanced by 35% during local night.
   Southern Australian Region:
      Near predicted monthly values during local day.
      Enhanced by 15% during local night.
      Enhanced by 30% after local dawn.
   Antarctic Region (Casey/Davis/Mawson):
      Near predicted monthly values over the UT day.

PCA Event : No event.

Monthly T index:
Month  T index
Nov      103
Dec      89
Jan      89


2. FORECAST (01 JANUARY - 03 JANUARY)
Date   T index  Conditions       MUFs                              
01 Jan   120    Normal           Near predicted monthly values 
                                 to 15% enhanced
02 Jan   110    Normal-poor      10-15% enhanced then depressed 
                                 20 to 30% late in the UT day    
03 Jan    60    Poor-normal      Depressed 20 to 30%/near predicted 
                                 monthly values   

COMMENT: ASWFC Preliminary HF Communications Warning 125 was 
issued on 29 December and is current for 31 Dec to 1 Jan. Maximum 
usable frequencies (MUFs) in the Australian region on UT day 
31-Dec were near predicted monthly values to 30% enhanced. The 
forecast geomagnetic activity on 31-Dec has failed to eventuate. 
MUFs are now expected to be 10-15% enhanced on 01-Jan. MUFs are 
initially expected to be 10-15% enhanced on 02-Jan then becoming 
depressed 20-30% late in the UT day due to the anticipated arrival 
of a CME associated with the M7 flare. MUFs on 03-Jan are expected 
to be 20-30% depressed. Isolated shortwave fadeouts are possible.

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For an explanation of some of the terms in this report, go to
https://www.sws.bom.gov.au, and follow links to Educational->
Glossary on Solar Terrestrial Terms.

Australian Space Weather Forecasting Centre
Bureau of Meteorology
ASWFC at bom.gov.au
www.bom.gov.au | www.sws.bom.gov.au