Solar Activity Alerts

:Product: Forecast Discussion :Issued: 2026 Sep 16 0130 UTC # Prepared by the U.S. Dept. of Commerce, NOAA, Space Weather Prediction Center # Solar Activity .24 hr Summary... Solar activity continued at very low levels with occasional B-class flaring. There are two numbered sunspot regions on the visible disk, both are stable unipolar groups. A CME off the NW limb was observed in LASCO C2 imagery starting at 15/1648 UTC. This ejecta is believed to be from the far side of the Sun as there was no indication through GOES SUVI imagery that an eruption happened on the visible disk. No Earth-directed CMEs were observed in available coronagraph imagery. .Forecast... Solar activity is expected to remain at very low levels, with a chance for isolated C-class flares through 18 Sep. Energetic Particle .24 hr Summary... The greater than 2 MeV electron flux was at moderate levels, with a peak flux of 427 pfu observed at 15/1710 UTC. The greater than 10 MeV proton flux has decreased to background levels. .Forecast... The greater than 2 MeV electron flux is expected to reach high levels through 18 Sep. The greater than 10 MeV proton flux is anticipated to remain at background levels through 18 Sep. Solar Wind .24 hr Summary... Solar wind parameters were enhanced possibly by negative CH HSS influence. The solar wind had two distinct and relatively short lived increases to +600 and +700 km/s, respectively, but decreased back to near 400 km/s each time. Total field reached a maximum of 17 nT just after 15/1700 UTC while Bz was mostly northward until 15/1852 UTC when a deflection south to -13 nT was observed. Phi was mostly negative. .Forecast... Negative polarity CH HSS effects are anticipated to persist through 18 Sep. Additional enhancements are likely on 16 and 17 Sep due to flanking influences from CMEs that departed the Sun on 13 and 14 Sep. Geospace .24 hr Summary... The geomagnetic field was quiet to unsettled. .Forecast... Geomagnetic activity is expected to reach active to G1 (Minor) storm levels on 16 and 17 Sep due to the combined CH and CME influences. Unsettled to active conditions are likely on 18 Sep as enhancements wane.

Space Weather Message Code: ALTK04 Serial Number: 2684 Issue Time: 2026 Sep 16 0034 UTC ALERT: Geomagnetic K-index of 4 Threshold Reached: 2026 Sep 16 0030 UTC Synoptic Period: 0000-0300 Active Warning: YES Comment: NOAA Space Weather Scale descriptions can be found at www.swpc.noaa.gov/noaa-scales-explanation Potential Impacts: Area of impact primarily poleward of 65 degrees Geomagnetic Latitude. Induced Currents - Weak power grid fluctuations can occur. Aurora - Aurora may be visible at high latitudes such as Canada and Alaska.

:Product: Forecast Discussion :Issued: 2026 Sep 16 0030 UTC # Prepared by the U.S. Dept. of Commerce, NOAA, Space Weather Prediction Center # Solar Activity .24 hr Summary... Solar activity continued at very low levels with occasional B-class flaring. There are two numbered sunspot regions on the visible disk, both are stable unipolar groups. A CME off the NW limb was observed in LASCO C2 imagery starting at 15/1648 UTC. This ejecta is believed to be from the far side of the Sun as there was no indication through GOES SUVI imagery that an eruption happened on the visible disk. No Earth-directed CMEs were observed in available coronagraph imagery. .Forecast... Solar activity is expected to remain at very low levels, with a chance for isolated C-class flares through 18 Sep. Energetic Particle .24 hr Summary... The greater than 2 MeV electron flux was at moderate to high levels, with a peak flux of 427 pfu observed at 15/1710 UTC. The greater than 10 MeV proton flux has decreased to background levels. .Forecast... The greater than 2 MeV electron flux is expected to continue at high levels through 18 Sep. The greater than 10 MeV proton flux is anticipated to remain at background levels through 18 Sep. Solar Wind .24 hr Summary... Solar wind parameters were enhanced possibly by negative CH HSS influence. The solar wind had two distinct and relatively short lived increases to +600 and +700 km/s, respectively, but decreased back to near 400 km/s each time. Total field reached a maximum of 17 nT just after 15/1700 UTC while Bz was mostly northward until 15/1852 UTC when a deflection south to -13 nT was observed. Phi was mostly negative. .Forecast... Negative polarity CH HSS effects are anticipated to persist through 18 Sep. Additional enhancements are likely on 16 and 17 Sep due to flanking influences from CMEs that departed the Sun on 13 and 14 Sep. Geospace .24 hr Summary... The geomagnetic field was quiet to unsettled. .Forecast... Geomagnetic activity is expected to reach active to G1 (Minor) storm levels on 16 and 17 Sep due to the combined CH and CME influences. Unsettled to active conditions are likely on 18 Sep as enhancements wane.

Space Weather Message Code: WARK05 Serial Number: 2265 Issue Time: 2026 Sep 15 1856 UTC WARNING: Geomagnetic K-index of 5 expected Valid From: 2026 Sep 15 1855 UTC Valid To: 2026 Sep 16 0600 UTC Warning Conditions: Onset Noaa Scale: G1 - Minor Comment: NOAA Scale: G1 - Minor NOAA Space Weather Scale descriptions can be found at www.swpc.noaa.gov/noaa-scales-explanation Potential Impacts: Area of impact primarily poleward of 60 degrees Geomagnetic Latitude. Induced Currents - Weak power grid fluctuations can occur. Spacecraft - Minor impact on satellite operations possible. Aurora - Aurora may be visible at high latitudes, i.e., northern tier of the U.S. such as northern Michigan and Maine.

Space Weather Message Code: WARK04 Serial Number: 5417 Issue Time: 2026 Sep 15 1850 UTC WARNING: Geomagnetic K-index of 4 expected Valid From: 2026 Sep 15 1849 UTC Valid To: 2026 Sep 16 0600 UTC Warning Conditions: Onset Comment: NOAA Space Weather Scale descriptions can be found at www.swpc.noaa.gov/noaa-scales-explanation Potential Impacts: Area of impact primarily poleward of 65 degrees Geomagnetic Latitude. Induced Currents - Weak power grid fluctuations can occur. Aurora - Aurora may be visible at high latitudes such as Canada and Alaska.

Space Weather Message Code: WATA20 Serial Number: 1125 Issue Time: 2026 Sep 15 1737 UTC WATCH: Geomagnetic Storm Category G1 Predicted Highest Storm Level Predicted by Day: Sep 16: G1 (Minor) Sep 17: G1 (Minor) Sep 18: None (Below G1) THIS SUPERSEDES ANY/ALL PRIOR WATCHES IN EFFECT Comment: NOAA Space Weather Scale descriptions can be found at www.swpc.noaa.gov/noaa-scales-explanation Potential Impacts: Area of impact primarily poleward of 60 degrees Geomagnetic Latitude. Induced Currents - Weak power grid fluctuations can occur. Spacecraft - Minor impact on satellite operations possible. Aurora - Aurora may be visible at high latitudes, i.e., northern tier of the U.S. such as northern Michigan and Maine.

:Product: Forecast Discussion :Issued: 2026 Sep 15 1230 UTC # Prepared by the U.S. Dept. of Commerce, NOAA, Space Weather Prediction Center # Solar Activity .24 hr Summary... Solar activity continued at very low levels with occasional B-class flaring. There are four numbered sunspot regions on the visible disk. All but Region 4531 (S08W02, Bxo/beta), which was numbered this period, are stable unipolar groups. No Earth-directed CMEs were observed in available coronagraph imagery. .Forecast... Solar activity is expected to remain at very low levels, with a decreasing chance for isolated C-class flares and a slight chance for M-class flares through 17 Sep. Energetic Particle .24 hr Summary... The greater than 2 MeV electron flux was at high to moderate levels, with a peak flux of 4,650 pfu observed at 14/1315 UTC. The greater than 10 MeV proton flux has declined but remains slightly elevated following a peak of 4 pfu observed at 14/1520 UTC. .Forecast... The greater than 2 MeV electron flux is expected to continue at high levels through 17 Sep. The greater than 10 MeV proton flux is anticipated to undergo a slow decline toward background levels through 17 Sep. Solar Wind .24 hr Summary... Solar wind parameters were slightly enhanced throughout the period, consistent with transient passage and the likely onset of a negative polarity coronal hole high-speed stream (-CH HSS). Total field strength (Bt) gradually rose to a peak of 14 nT after 14/1800 UTC before reaching as high as 16 nT late in the period. The North-South (Bz) component was variable in the first half of the period and reached a maximum southward deflection of -9 nT before turning and remaining northward after 14/2230 UTC. Solar wind speeds held relatively slow between 350 and 380 km/s before climbing sharply after 15/1114 UTC to over 600 km/s. This wind speed increase was a notable sharp rise in temperature. The phi angle shifted into a predominantly negative (towards the Sun) early in the period. .Forecast... Negative polarity CH HSS effects are anticipated to persist through 17 Sep. Additional enhancements are likely on 16 and 17 Sep due to flanking influences from CMEs that departed the Sun on 13 and 14 Sep. Geospace .24 hr Summary... The geomagnetic field was at quiet to active levels in response to transient influences. .Forecast... Geomagnetic activity is expected to reach active to G1 (Minor) storm levels on 15 and 16 Sep, with G1 conditions remaining possible on 17 Sep due to combined CH and CME effects.