Summary and Forecast

Solar Summary

(last updated 17 Jul 2026 23:30 UT)

Activity 17 Jul: R0 Flares: none. Observed 10.7 cm flux/Equivalent Sunspot Number for 17 Jul: 105/54

Solar Forecast

(last updated 17 Jul 2026 23:30 UT)

18 Jul 19 Jul 20 Jul Activity R0 R0, chance of R1 R0, chance of R1 Fadeouts None expected None expected None expected 10.7cm/SSN 110/60 115/66 120/72 COMMENT: Solar flare activity on UT day 17-Jul was at the R0 level, with no significant flaring activity. There are currently two numbered active regions (ARs) visible on the solar disk. Region 4489 (S07E14, beta) is the largest on the disk and was mostly stable over the UT day. Region 4491 (S11E48, alpha) showed some decay. An unnumbered region is visible near S17E38 (alpha) and has shown mild spot growth. Solar flare activity is expected to be at the R0 level on 18-Jul, increasing to R0, with a chance of R1 over 19-20 Jul due to a new region rotating onto the visible disk. S0 solar radiation storm conditions were observed on UT day 17-Jul. S0 solar radiation storm conditions are expected over 18-20 Jul. No Earth-directed coronal mass ejections (CMEs) have been observed. An east-directed CME was observed, visible in LASCO C2 coronagraph imagery from 17/0012UT. This CME is considered to be a farside event and therefore not geoeffective. Similarly, a west-directed CME observed at 17/1800UT is considered farside and not Earth-directed. The solar wind speed on UT day 17-Jul decreased, ranging from 430 to 350 km/s and is currently near 350 km/s. The peak total interplanetary magnetic field strength (IMF, Bt) was 4 nT and the north-south IMF component (Bz) range was -4 to +3 nT. The solar wind speed is expected to remain at background levels over 18-20 Jul.

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