Summary and Forecast

Solar Summary

(last updated 17 Sep 2025 23:30 UT)

Activity 17 Sep: R0 Flares: none. Observed 10.7 cm flux/Equivalent Sunspot Number for 17 Sep: 147/101

Solar Forecast

(last updated 17 Sep 2025 23:30 UT)

18 Sep 19 Sep 20 Sep Activity R0-R1 R0-R1 R0-R1 Fadeouts Possible Possible Possible 10.7cm/SSN 148/102 150/105 150/105 COMMENT: Solar activity on UT day 17-Sep was R0, with no solar flares. There are currently nine numbered sunspot regions on the solar disk. AR4220 (S18E00, beta) has shown the most growth over the past day. Regions AR4221 (N04E29, beta), AR4222 (N11E07, beta) and AR4223 (S15E49, beta) have shown some minor growth in the past day. Solar activity is expected to be R0-R1 over 18-20 Sep. No Earth directed CMEs were observed in available imagery. S0 solar radiation storm conditions were observed on UT day 17-Sep. S0 solar radiation storm conditions are expected over 18-20 Sep. The solar wind environment on UT day 17-Sep was steady. The solar wind speed ranged from 74 trending down to 564 km/s. The peak total interplanetary field strength (IMF, Bt) was 5 nT and the north-south IMF component range (Bz) was +4 to -4 nT. The solar wind environment is expected to be near background levels over 18-20 Sep.

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