Summary and Forecast

Solar Summary

(last updated 25 Sep 2026 23:30 UT)

Activity 25 Sep: R0 Flares: none. Observed 10.7 cm flux/Equivalent Sunspot Number for 25 Sep: 105/54

Solar Forecast

(last updated 25 Sep 2026 23:30 UT)

26 Sep 27 Sep 28 Sep Activity R0 R0 R0 Fadeouts None expected None expected None expected 10.7cm/SSN 100/48 95/41 95/41 COMMENT: Solar flare activity on UT day 25-Sep was at the R0 level, with only low-level C-class flares observed. There are currently eight numbered sunspot regions and one unnumbered region visible on the solar disk. Active region (AR) 4536 (N03W52, beta-gamma) is currently the largest region and has seen some mild decay over the past UT day. The unnumbered region (S09W41, beta) has shown some east-west separation over the UT day. All other sunspot regions are either stable or in decay. Solar flare activity is expected to be at the R0 level over 26-28 Sep. Solar radiation storm conditions were at the S0 level on 25-Sep, with the solar proton flux at background levels. S0 solar radiation storm conditions are forecast over 26-28 Sep. No Earth-directed coronal mass ejections (CMEs) were observed over the past UT day. The solar wind speed on UT day 25-Sep was largely stable over the day, increasing slightly before decreasing again in the latter half of the day. Speeds ranged from 400 to 550 km/s, and is currently near 490 km/s. The peak total interplanetary magnetic field strength (IMF, Bt) was 10 nT. The north-south component (Bz) ranged between -10 and +7 nT over the same period. Sustained periods of southward IMF were observed over most of the UT day. The solar wind speed is expected to remain elevated over 26-28 Sep due to ongoing coronal hole high speed wind stream effects from a southern coronal hole before entering another high speed wind stream from a northern hemisphere coronal hole over 26-Sep.

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