Official Space Weather Advisory issued by NOAA Space Weather Prediction Center
Boulder, Colorado, USA
SPACE WEATHER ADVISORY OUTLOOK #26-35
2026 September 6 at 8:46 p.m. MDT (2026 September 7 0246 UTC)
**** SPACE WEATHER OUTLOOK ****
Summary For August 31-September 6
Solar activity was at moderate levels on 02 Sep and 04-05 Sep due to three R1 (Minor) M-class
flares, and low levels on the remaining days. The largest flare of the period was an M3.0 at
02/1920 UTC from Region 4524 (N12, L=224, class/area Cso/100 on 05 Sep), which was also
responsible for another M1.2/1n at 04/0753 UTC and 11 C-class flares throughout the period.
The M3.0 was accompanied by Type II (estimated velocity 1181 km/s) and IV radio sweeps and
a CME first observed in LASCO C2 at ~02/1936 UTC, which modeling indicated would pass
behind Earth orbit.
The last R1 was an M1.0/1f at 05/1518 UTC from Plage Region 4520 (S12, L=337, class/area
Dai/40 on 01 Sep); this region had fully decayed to plage on 03 Sep. An associated CME first
became visible in LASCO C2 at ~ 05/1800 and in STEREO coronagraph imagery at ~05/1608
UTC as a halo. Modeling indicated this eruption would pass ahead of Earth orbit.
Notably, Plage Region 4518 (N07, L=354, class/area Cri/30 on 26 Aug), which had fully
decayed to plage on 03 Sep as well, also produced a C1.3 at 04/1527 UTC.
7 additional CMEs were observed this reporting period. Coronal dimming seen in GOES/SUVI
195 starting ~02/0910 UTC was associated with a CME first seen in STEREO coronagraph
imagery at ~02/1108 UTC; modeling indicated that the bulk of the material is likely to pass
ahead of Earth orbit but a glancing blow on 07 Sep was possible. A C7.9/Sn at 03/1630 UTC
from Region 4524 was accompanied by a Type II radio sweep (estimated velocity 1359 km/s)
and a CME first observed in LASCO C2 at ~03/1636 UTC, which modeling indicated would not
hit Earth. A C6.7/Sf at 04/1930 UTC from Region 4524 was accompanied by Type II (estimated
velocity 698 km/s) and IV radio sweeps and a CME first visible in LASCO C2 at ~04/1924 UTC
and STEREO at ~ 04/2030 UTC; modeling indicates this eruption may swallow the 02 Sep
eruption and produce a glancing blow at Earth either late 07 Sep or early 08 Sep. A north-south
filament just SE of disk-center began erupting at ~05/0530 UTC, and an associated CME was
first observed in STEREO coronagraph imagery at ~05/0638 UTC. A C6.4/1n at 05/1045 UTC
from Region 4524 was associated with a CME first observed in LASCO C2 at ~ 05/1112 UTC.
A C8.5/2n at 05/1746 UTC from Region 4524 was associated with a CME first observed in
LASCO C2 at ~05/1800. Modeling indicates that these three CMEs may have a merged arrival at
Earth on 08 Sep. Finally, a C5.0/1n at 06/1042 UTC from Region 4524 was associated with a
CME first observed in STEREO coronagraph imagery at ~06/1053 UTC, which modeling
indicates may produce an arrival at Earth late 08 Sep or early 09 Sep.
Proton levels at geosynchronous orbit rapidly enhanced on 05 Sep in response to the M1.0 from
Plage Region 4520. The greater than 100 MeV proton flux crossed the 1 pfu threshold at 05/1545 UTC, peaked at 05/1550 UTC at 1.16 pfu, and crossed back below the threshold at 05/1615 UTC. The greater than 10 MeV proton flux crossed the 10 pfu threshold at 05/1615 UTC, peaked at 05/1645 UTC at 18 pfu, and crossed back below the threshold at 05/2135 UTC.
The greater than 2 MeV electron flux at geosynchronous orbit was at high levels from 31Aug -04 Sep and on 06 Sep, returning to normal to moderate levels on 05 Sep.
Geomagnetic field activity was at unsettled levels 31 Aug-01 Sep and 05 Sep, and was otherwise
at quiet levels.
Outlook For September 7-13
Solar activity is expected to be at low levels, with a chance for moderate levels and a slight chance for high levels throughout the forecast period.
No proton events are expected at geosynchronous orbit.
The greater than 2 MeV electron flux at geosynchronous orbit is expected to be at high levels on
09-12 Sep, 16-23 Sep, and 27 Sep-03 Oct. Levels are expected to be at normal to moderate levels on 07-08 Sep, 13-15 Sep, and 24-26 Sep.
Geomagnetic field activity is expected reach active to G1 storming levels on 07-08 Sep due to
the anticipated arrivals of the CMEs discussed above. G1 storming levels are again anticipated
on 24-26 Sep due to a recurrent positive polarity coronal hole high speed stream (CH HSS), with
active levels anticipated on 27 Sep. Active levels are also anticipated on 14-16 Sep due to a
recurrent negative polarity CH HSS. Largely quiet levels are anticipated for all remaining dates
in the forecast period.
Data used to provide space weather services are contributed by NOAA,
USAF, NASA, NSF, USGS, the International Space Environment Services
and other observatories, universities, and institutions. More
information is available at SWPC's Web site http://swpc.noaa.gov
