Summary and Forecast
Solar Summary
(last updated 21 Dec 2025 23:30 UT)
Activity 21 Dec: R1 Flares Max Fadeout Freq. Sectors M1.3 1827UT possible lower East Pacific/ North American Observed 10.7 cm flux/Equivalent Sunspot Number for 21 Dec: 124/77
Solar Forecast
(last updated 21 Dec 2025 23:30 UT)
22 Dec 23 Dec 24 Dec Activity R0-R1 R0-R1 R0-R1 Fadeouts Possible Possible Possible 10.7cm/SSN 130/84 135/89 140/94 COMMENT: Solar activity was at the R1 level on UT day 21-Dec, with an M1.3 flare observed at 21/1827UT, originating from Active Region (AR) 4316 (S07E27, beta-gamma). This region has increased in size and magnetic complexity over the last 24 hours. It is one of four regions on the visible solar disk. AR4311 (N04W55, alpha) also exhibited growth, before decaying late in the UT day. Active Region 4317 (N13E66, beta) continues to rotate from the eastern limb, with additional nearby spots also rotating into view. All other regions appear stable. Solar activity is expected to be at R0-R1 over the period 22-24 Dec, given the past flare activity of AR4316. S0 solar radiation storm conditions were observed over the past 24 hours, with the proton flux remaining at background values. S0 conditions are forecast to continue over the period 22-24 Dec. No Earth-directed Coronal Mass Ejections have been observed over the past UT day with available coronograph imagery. Solar wind speeds increased over 21-Dec as Earth connected with a coronal hole high-speed wind stream, increasing from 380-420 km/s early in the UT day to reach 620-660 km/s by 21/0900UT. An additional small increase in wind speed was observed at 21/2000UT, with speeds now ranging between 680-720 km/s. An increase in the interplanetary magnetic field strength (IMF, Bt) accompanied the increase in wind speed, and peaked at 15 nT. The north-south component (Bz) ranged from -12 to +9 nT over this period, with periods of extended southward Bz between 21/0515-0615UT and 21/1250-1450UT. The solar wind speed is forecast to remain very strong over 22-23 Dec, before decreasing on 24-Dec as the ongoing effects of the coronal hole high speed wind stream wane.
Solar Activity levels are explained in the SWS Solar Terrestrial Glossary.
