Ionospheric Summary and Forecast

Ionospheric Summary

(last updated 23 Jun 2025 23:30 UT)

Date T index 23 Jun 74 Observed Australian Regional MUFs Cocos Island Region: Near predicted monthly values during local day. Depressed by 25% during local night. Depressed by 25% after local dawn. Niue Island Region: Depressed by 15% during local day. Near predicted monthly values during local night. Northern Australian Region: Depressed by 15% during local day. Depressed by 30% during local night. Depressed by 20% after local dawn. Southern Australian Region: Depressed by 20% during local day. Near predicted monthly values during local night. Antarctic Region (Casey/Davis/Mawson): Depressed by 20% over the UT day. Sporadic E and spread F frequently observed. Monthly T index: Month T index May 94 Jun 109 Jul 107

Ionospheric Forecast

(last updated 23 Jun 2025 23:30 UT)

Date T index MUFs 24 Jun 90 Depressed 10 to 15%/near predicted monthly values 25 Jun 80 Depressed 10 to 15%/near predicted monthly values 26 Jun 65 Depressed 15 to 20%/near predicted monthly values COMMENT: ASWFC HF Communications Warning 67 was issued on 21 June and is current for 22-24 Jun. Maximum usable frequencies (MUFs) in the Australian region on UT day 23-Jun were generally 15 to 30% depressed. Spread F was observed at Canberra, Townsville, Hobart and Norfolk Island during local hight hours. Antarctic HF conditions were degraded. MUFs are expected to be 10-15% depressed to near predicted monthly values 24-25 Jun, with degraded HF conditions for the southern Australian region on 25-Jun during local night hours due to expected geomagnetic activity from a coronal hole wind stream. Southern Australian region MUFs are expected to be 15 to 20% depressed on 26-Jun.