Ionospheric Summary and Forecast

Ionospheric Summary

(last updated 20 Mar 2026 23:30 UT)

Date T index 20 Mar 95 Observed Australian Regional MUFs Cocos Island Region: Enhanced by 25% during local day. Enhanced by 30% during local night. Niue Island Region: Near predicted monthly values during local day. No data available during local night. Northern Australian Region: Mostly near predicted monthly values. Southern Australian Region: Mostly near predicted monthly values. Antarctic Region (Casey/Davis/Mawson): Depressed by 15% over the UT day. Monthly T index: Month T index Feb 98 Mar 87 Apr 85

Ionospheric Forecast

(last updated 20 Mar 2026 23:30 UT)

Date T index MUFs 21 Mar 55 Depressed by up to 20% 22 Mar 65 Depressed by up to 20% 23 Mar 80 Near predicted monthly values to 15% depressed COMMENT: ASWFC Preliminary HF Communications Warning 27 was issued on 19 March and is current for 20-21 Mar. Maximum usable frequencies (MUFs) in the Australian region on UT day 20-Mar were near predicted values. Some spread-F was observed in Hobart during local night hours. MUFs are expected to become depressed by 20% early on 21-Mar and continue through to 23-Mar but improving on this last day. Spread-F is possible at middle and high latitudes and scintillation may be possible in equatorial regions. The source of this activity is an anticipated CME from 18-Mar coupled with coronal hole activity.