Product: Weekly Highlights and Forecasts
:Issued: 2026 Sep 21 0317 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 14 - 20 September 2026
Solar activity was at very low levels on 14-18 Sep and increased to
low levels on 19-20 Sep. Region 4535 (N12, L=353, class/area Hrx/020
on 20 Sep) produced a C1.1 flare at 20/0518 UTC, while Region 4534
(N11, L=074, class/area Dro/030 on 20 Sep) produced a C3.7/1f flare
at 20/2234 UTC, the largest of the period. No Earth-directed CMEs
were detected during the highlight period.
No proton events were observed at geosynchronous orbit.
The greater than 2 MeV electron flux at geosynchronous orbit was at
high levels on 14 Sep when a maximum flux of 4,650 pfu was observed
at 14/1315 UTC. Low to moderate levels were observed on 15-20 Sep.
Geomagnetic field activity reached unsettled levels on 14-17 Sep,
with isolated active levels observed on 14 and 16 Sep. Unsettled to
active levels were observed on 14 Sep due to a southern hemisphere
filament eruption coupled with a SSBC. Unsettled levels were
observed on 15-17 Sep, with an isolated active period early on 16
Sep, all due to negative polarity CH HSS effects. Quiet to isolated
unsettled levels were observed on 18-20 Sep.
Forecast of Solar and Geomagnetic Activity 21 September - 17 October 2026
Solar activity is expected to be <span style="color: rgb(0, 0, 0);
white-space: pre-wrap;">at low levels, with a slight chance
</span><span style="color: rgb(0, 0, 0); white-space: pre-wrap;">for
moderate to high levels throughout the forecast period. </span>
<span style="color: rgb(0, 0, 0); white-space: pre-wrap;">No proton
events are expected at geosynchronous orbit.</span>
The greater than 2 MeV electron flux at geosynchronous orbit is
expected to be at high levels on 26-30 Sep, 01-03 Oct, and 05-11
Oct. Low to moderate levels are expected on 21-25 Sep, 04 Oct, and
12-17 Oct.
Geomagnetic field activity is expected to <span style="color: rgb(0,
0, 0); white-space: pre-wrap;">reach active to G1 </span><span
style="color: rgb(0, 0, 0); white-space: pre-wrap;">storm levels on
24-25 Sep due to positive polarity CH HSS effects. Unsettled to
active levels are expected on 26-27 Sep and 04-08 Oct due to
positive polarity CH HSS effects. Quiet to unsettled levels are
expected on 11-14 Oct due to negative polarity CH HSS effects.
Largely quiet levels are anticipated for all remaining dates in the
forecast period.</span>
Product: 27-day Space Weather Outlook Table 27DO.txt
:Issued: 2026 Sep 21 0317 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 2026-09-21
#
# UTC Radio Flux Planetary Largest
# Date 10.7 cm A Index Kp Index
2026 Sep 21 105 5 2
2026 Sep 22 105 5 2
2026 Sep 23 100 5 2
2026 Sep 24 100 20 4
2026 Sep 25 105 18 5
2026 Sep 26 105 12 3
2026 Sep 27 100 8 3
2026 Sep 28 105 5 2
2026 Sep 29 110 5 2
2026 Sep 30 115 5 2
2026 Oct 01 115 5 2
2026 Oct 02 110 5 2
2026 Oct 03 105 5 2
2026 Oct 04 110 12 3
2026 Oct 05 110 15 4
2026 Oct 06 115 12 4
2026 Oct 07 115 10 3
2026 Oct 08 110 8 3
2026 Oct 09 105 5 2
2026 Oct 10 110 5 2
2026 Oct 11 100 9 3
2026 Oct 12 97 8 3
2026 Oct 13 96 8 3
2026 Oct 14 95 8 3
2026 Oct 15 100 5 2
2026 Oct 16 105 5 2
2026 Oct 17 100 5 2
(NOAA)
