Summary and Forecast

Solar Summary

(last updated 16 Dec 2025 23:30 UT)

Activity 16 Dec: R0 Flares: none. Observed 10.7 cm flux/Equivalent Sunspot Number for 16 Dec: 117/69

Solar Forecast

(last updated 16 Dec 2025 23:30 UT)

17 Dec 18 Dec 19 Dec Activity R0 R0 R0 Fadeouts None expected None expected None expected 10.7cm/SSN 118/70 118/70 115/66 COMMENT: Solar activity on UT day 16-Dec was R0, with no solar flares. There are currently five numbered sunspot regions on the solar disk. Overall the regions are all either stable or decaying, however several regions went through a short growth phase before maturing. Solar activity is mostly expected to be R0 over 17-19 Dec. No CMEs were observed on UT day 16-Dec. S0 solar radiation storm conditions were observed on UT day 16-Dec. S0 solar radiation storm conditions are expected over 17-19 Dec. On UT day 16-Dec the solar wind environment was mildly disturbed. The solar wind speed steadily increased and ranged from 500-700km/s, but is now coming down from its peak. The maximum total interplanetary field strength (IMF, Bt) was 14nT and the north-south IMF component range (Bz) was +12 to -8nT. The source of this disturbance was likely a weak transience, or else possibly the early arrival of the anticipated coronal hole. Should the coronal hole still be expected to connect with Earth, the solar wind is expected to increase late on 17-Dec into 18-Dec. Otherwise, the solar wind is expected to return to background levels.

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