Product: Weekly Highlights and Forecasts
:Issued: 2025 Sep 08 0224 UTC
# Prepared by the US Dept. of Commerce, NOAA, Space Weather Prediction Center
# Product description and SWPC web contact www.swpc.noaa.gov/content/subscription-services
#
# Weekly Highlights and Forecasts
#
Highlights of Solar and Geomagnetic Activity 01 - 07 September 2025
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Solar activity reached moderate levels (R1-MInor) over 04 Sep, 05 Sep, and 06 Sep. All M-class flares were attributed to Region 4207 (S29, L=045, class/area=Fhi/390 on 04 Sep). The remaining 17 numbered active regions on the visible disk in the past week were either quiet or only produced C-class events.
Other significant activity included a CME that erupted from a filament centered near N12W04 around 04/1945 UTC. This resulted in a halo CME signature in subsequent coronagraph imagery. Initial modelling of the event suggested arrival early on the 07 Sep. Observed arrival was mid-to-late on 06 Sep.
The proton flux at geosynchronous orbit remained below the S1 (Minor) threshold.
The greater than 2 MeV electron flux at geosynchronous orbit was at normal to moderate levels.
Geomagnetic field activity was ranged from quiet to G2 (Moderate) levels. G2 conditions observed on 01 Sep were attributed to the onset of a CME that left the Sun on 30 Aug. Total magnetic field strength reached a peak of 25 nT and the Bz component was observed as far south as -23 nT at 02/0000 UTC. Shock arrival at ACE was observed at 01/2030 UTC, marked by a solar wind speed increase from ~410 km/s to ~645 km/s. A sudden impulse was observed at Earth at 01/2101 UTC. G1 (Minor) activity was observed on 02 and 03 Sep during the waning phase off the CME. Quiet conditions were observed over 04-05 Sep. An increase in activity was observed on 06 Sep, with
a G1 period marking the arrival of a CME that left the Sun on 04 Sep. Total magnetic field strength reached an initial peak of 21 nT at 06/1407 UTC. The Bz component rotated as far south as -10 nT. The solar wind speeds increased to ~700 km/s. The Bz component rotated northward shortly after which resulted in mostly quiet conditions ov07 Sep during the waning phase of the CME.
Forecast of Solar and Geomagnetic Activity 08 September - 04 October 2025
Solar activity is expected to be mostly low, with a chance for moderate (R1-R2/Minor-Moderate), over the outlook period due to multiple complex regions both on the visible disk and expected to return from the Sun's farside.
No proton events are expected at geosynchronous orbit.
The greater than 2 MeV electron flux at geosynchronous orbit is expected to reach high levels over 08-11 Sep and 20-21 Sep due to multiple, recurrent CH HSSs. The remainder of the outlook period is expected to be at normal to moderate levels.
Geomagnetic field activity is expected to range from quiet to G1 (Minor) geomagnetic storm levels. G1 conditions are likely on 15 Sep; active conditions are likely on 08 Sep, 14 Sep, 16 Sep, 28-29 Sep, and 03-04 Oct; unsettled conditions are likely on 09-10 Sep, 17-19 Sep, and 30 Sep. All increases in geomagnetic activity are in anticipated of multiple, recurrent CH HSSs. The remainder of the outlook period is likely to be mostly quiet.
Product: 27-day Space Weather Outlook Table 27DO.txt
:Issued: 2025 Sep 08 0225 UTC
# Prepared by the US Dept. of Commerce, NOAA, Space Weather Prediction Center
# Product description and SWPC web contact www.swpc.noaa.gov/content/subscription-services
#
# 27-day Space Weather Outlook Table
# Issued 2025-09-08
#
# UTC Radio Flux Planetary Largest
# Date 10.7 cm A Index Kp Index
2025 Sep 08 135 12 4
2025 Sep 09 135 8 3
2025 Sep 10 130 8 3
2025 Sep 11 125 5 2
2025 Sep 12 125 5 2
2025 Sep 13 120 5 2
2025 Sep 14 125 12 4
2025 Sep 15 130 20 5
2025 Sep 16 135 15 4
2025 Sep 17 135 8 3
2025 Sep 18 140 8 3
2025 Sep 19 145 8 3
2025 Sep 20 145 5 2
2025 Sep 21 150 5 2
2025 Sep 22 150 5 2
2025 Sep 23 150 5 2
2025 Sep 24 155 5 2
2025 Sep 25 155 5 2
2025 Sep 26 155 5 2
2025 Sep 27 160 5 2
2025 Sep 28 155 12 4
2025 Sep 29 150 15 4
2025 Sep 30 150 8 3
2025 Oct 01 145 5 2
2025 Oct 02 140 5 2
2025 Oct 03 140 15 4
2025 Oct 04 140 12 4
(NOAA)
