Summary and Forecast

Solar Summary

(last updated 15 May 2026 23:30 UT)

Activity 15 May: R0 Flares: none. Observed 10.7 cm flux/Equivalent Sunspot Number for 15 May: 101/49

Solar Forecast

(last updated 15 May 2026 23:30 UT)

16 May 17 May 18 May Activity R0 R0 R0 Fadeouts None expected None expected None expected 10.7cm/SSN 100/48 100/48 100/48 COMMENT: Solar flare activity on UT day 15-May was at the R0 level, the largest flare of the day was a C9.5 flare observed at 15/1614UT. There are currently three numbered sunspot regions visible on the solar disk. AR4438 (N19W54, beta) showed spot separation over the UT day. AR4435 (N23W78, beta) was stable and produced the largest flare of the UT day. No large or significantly magnetically complex regions exist on the solar disk. Solar flare activity is expected to be at the R0 level over 16-18 May, with a chance of R1. S0 solar proton conditions were observed on UT day 15-May. S0 solar proton conditions are expected over 16-18 May. No Earth-directed CMEs have been observed on 15-May. A north directed CME is visible in SOHO and STEREO-A imagery from 15/0418UT, associated with a filament eruption at around N20E05 from 15/0250UT visible in SDO, GOES SUVI and H-Alpha imagery. This CME is expected to pass above the Earth. The solar wind speed on UT day 15-May increased due to coronal hole high speed wind stream effects, ranging from 385 to 750 km/s and is currently near 640 km/s. The peak total interplanetary magnetic field strength (IMF, Bt) was 17 nT and the north-south IMF component (Bz) range was -14 to +10 nT. The solar wind speed is expected to remain elevated over 16-18 May due to ongoing coronal hole high speed wind stream effects.

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