Summary and Forecast

Solar Summary

(last updated 21 May 2026 23:30 UT)

Activity 21 May: R0 Flares: none. Observed 10.7 cm flux/Equivalent Sunspot Number for 21 May: 118/70

Solar Forecast

(last updated 21 May 2026 23:30 UT)

22 May 23 May 24 May Activity R0, chance of R1 R0, chance of R1 R0, chance of R1 Fadeouts Possible Possible Possible 10.7cm/SSN 120/72 120/72 125/78 COMMENT: Solar flare activity on UT day 21-May was at the R0 level, with a C9.5 flare observed at 21/1825UT. There are currently four numbered sunspot regions visible on the solar disk. AR4436 (N20W89, beta) was responsible for the largest flare of the UT day but has rotated off the solar disk over the UT day. AR4441 (N08W39, beta-gamma) and AR4443 (S16E10, beta) showed some spot development over the UT day, AR4441 is the largest and most magnetically complex. All other sunspot regions are either stable or in decay. Solar flare activity is expected to be at the R0 level over 22-24 May, with a chance of R1. S0 solar radiation conditions were observed on UT day 21-May. S0 solar radiation conditions are expected over 22-24 May. No Earth-directed coronal mass ejections (CMEs) were observed on 21-May. The solar wind speed decreased over 21-May. The speed ranged from 380 to 480 km/s and is currently near 410 km/s. The peak total interplanetary magnetic field strength (IMF, Bt) was 5 nT and the north-south IMF component (Bz) range was -4 to +4 nT. The solar wind speed is expected to continue to decline towards background levels and remain there over 22-24 May.

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