Solar activity on UT day 22-Dec is expected to be at the R0-R1 level. S0 solar radiation storm conditions are expected. The solar wind speed is expected to be very strong over the UT day. G0-G1 geomagnetic conditions are expected. HF radio propagation conditions are expected to be Fair-normal across the Australian region. Maximum usable frequencies (MUFs) in the Australian region are expected to be depressed 15-20% compared with monthly values.