Summary and Forecast

Solar Summary

(last updated 17 Mar 2026 23:30 UT)

Activity 17 Mar: R1 Flares Max Fadeout Freq. Sectors M1.3 0904UT possible lower Mid East/Indian Observed 10.7 cm flux/Equivalent Sunspot Number for 17 Mar: 111/62

Solar Forecast

(last updated 17 Mar 2026 23:30 UT)

18 Mar 19 Mar 20 Mar Activity R0-R1 R0-R1 R0-R1 Fadeouts Possible Possible Possible 10.7cm/SSN 112/63 110/60 110/60 COMMENT: Solar activity on UT day 17-Mar was R1, with an isolated M1.3 class solar flare from active region (AR) 4392 (S15E016, beta). There are currently five numbered sunspot regions on the solar disk. Most regions have gone through another growth phase in the past day, which was followed by a decay phase. AR4392 is the largest region on the disk, but overall does not show significant magnetic complexity. Solar activity is expected to be R0-R1 over 18-20 Mar. A narrow CME can be seen from 0638 UT in STEREO-A imagery only, although the source of this event is not clear. If this event is from the frontside of the Sun, it may have a weak impact late on 19-Mar, along with another CME. S0 solar radiation storm conditions were observed on UT day 17-Mar. S0 solar radiation storm conditions are expected over 18-20 Mar. On UT day 17-Mar the solar wind environment was undisturbed, as the solar wind speed continued to decline from the recent coronal hole event. The solar wind speed ranged from near 500 km/s trending to 450 km/s. The peak total interplanetary field strength (IMF, Bt) was 5 nT. The north-south IMF component range (Bz) was +4 to -3 nT. The solar wind environment is expected to be near background conditions on 18-Mar. By late 19-Mar a recent CME is expected to arrive, with effects continuing into 20-Mar.

Solar Activity levels are explained in the SWS Solar Terrestrial Glossary.