Summary and Forecast

Solar Summary

(last updated 20 Jul 2026 23:30 UT)

Activity 20 Jul: R1 Flares Max Fadeout Freq. Sectors M2.5 1436UT possible lower South American/ Atlantic M1.1 1920UT possible lower East Pacific/ North American M3.4 2225UT possible lower East Pacific/ North American Observed 10.7 cm flux/Equivalent Sunspot Number for 20 Jul: 137/91

Solar Forecast

(last updated 20 Jul 2026 23:30 UT)

21 Jul 22 Jul 23 Jul Activity R1, chance of R2 R1, chance of R2 R1, chance of R2 Fadeouts Possible Possible Possible 10.7cm/SSN 140/94 142/96 145/99 COMMENT: Solar flare activity on UT day 20-Jul was at the R1 level, with an M2.5 flare peaking at 20/1436UT, an M1.1 flare peaking at 20/1920UT, and an M3.4 flare peaking at 20/2225UT. All of these flares have originated from Active Region (AR) 4493 (N05E10, beta-gamma-delta), which is the most magnetically complex region on the disk. This region is one of four numbered and two unnumbered regions on the disk, and has continued to show growth over the last UT day, including the development of a delta spot. All other numbered regions are stable or in decay. Two new regions have rotated onto the front side of the disk in the last 24 hours. These regions are presently located at S25E68 and S05E87, and both appear to have a beta magnetic classification. The latter region may be the return of the previously flare-active region 4478. Solar flare activity is forecast to be at the R1 level over 21-23 Jul, with a chance of R2, due to the continued growth and ongoing flare activity of AR 4493. S0 solar radiation storm conditions persisted throughout 20-Jul, with S0 conditions forecast for 21-23 Jul. No Earth-directed coronal mass ejections (CMEs) have been observed in coronagraph imagery over the past UT day. A west-directed medium-velocity CME was observed in SOHO/LASCO from 20/1236UT, with modelling indicating this will pass ahead of the Earth. The solar wind environment was consistent with background conditions over 20-Jul, with the solar wind speed ranging between 260-290 km/s throughout the UT day. The interplanetary magnetic field strength (IMF, Bt) peaked at 7 nT, with the north-south component (Bz) ranging between -4 and +3 nT over the UT day. The solar wind speed is expected to remain at background levels over 21-Jul, before rising on 22-Jul due to a coronal hole high speed wind stream connecting with Earth. The solar wind speed will remain elevated on 23-Jul as the high speed wind stream effects continue.

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