Summary and Forecast

Solar Summary

(last updated 27 Jun 2026 23:30 UT)

Activity 27 Jun: R0 Flares: none. Observed 10.7 cm flux/Equivalent Sunspot Number for 27 Jun: 188/141

Solar Forecast

(last updated 27 Jun 2026 23:30 UT)

28 Jun 29 Jun 30 Jun Activity R0-R1 R0-R1 R0-R1 Fadeouts Possible Possible Possible 10.7cm/SSN 175/129 175/129 180/133 COMMENT: Solar flare activity on UT day 27-Jun was at the R0 level, with a C7.4 flare from active region (AR) 4475 (S08W19, gamma) being the largest flare observed. There are currently six active sunspot regions on the disk, with AR 4478 (S06E34, beta‑gamma‑delta) being the largest and most magnetically complex region. This region showed mild growth over the past UT day. Both AR 4475 and AR 4479 (N17E18, beta) also showed some growth over the same period. A new region, numbered 4480, has appeared at S18E10, exhibiting a beta magnetic classification. The remaining regions are either stable or in decay. Solar flare activity is forecast to be at the R0-R1 level over 28-30 Jun, due to the magnetic complexity of ARs 4475 and 4478. Solar radiation storm conditions were at the S0 level throughout 27-Jun, and are forecast to remain at the S0 level through 28-30 Jun. A low-velocity south-directed coronal mass ejection (CME) was observed from 26/2112UT in SOHO/LASCO, following a C2.5 flare from AR 4475. Modelling suggests this CME will have a partial impact with Earth on 30-Jun at 30/1900UT +/- 10 hours. The solar wind speed declined across 27-Jun as the effects of a coronal hole high speed wind stream began to subside. The solar wind speed began the UT day at 650-680km/s, and slowly declined to between 500 and 530 km/s. The interplanetary magnetic field strength (IMF, Bt) peaked at 4 nT, with the north-south component (Bz) ranging between -3 and +3 nT. The solar wind is expected to continue declining over 28-30 Jun, before rising late on 30-Jun due to the arrival of the CME first seen on 26-Jun.

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