Subject: Weekly Highlights of Solar and Geomagnetic Activity, 13 - 19 October 2025

:Product: Weekly Highlights and Forecasts
:Issued: 2025 Oct 20 0159 UTC
# Prepared by the US Dept. of Commerce, NOAA, Space Weather Prediction Center
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# Weekly Highlights and Forecasts
#
Highlights of Solar and Geomagnetic Activity
13 - 19 October 2025

Solar activity was at moderate levels with 28 total M-class flares.
25 of these flares were produced by Region 4246 (N24, L=290,
class/area=Ekc/840 on 16 Oct), the largest of which was an M4.8/Sf
at 15/0415 UTC. Several of the flares from this region were the
source of partially Earth-directed CMEs as flanking ejecta impacted
the near-Earth environment on 17-18 Oct. Region 4248 (N07, L=261, class/area=Eki/310 on 15 Oct) also produced an M2.0 flare at 14/1247
UTC. These regions were classified as beta-gamma-delta. The
remaining regions during this highlight period produced C-class
activity but were otherwise unremarkable.

No proton events were observed at geosynchronous orbit.

The greater than 2 MeV electron flux at geosynchronous orbit reached
high levels on 13-17 Oct due in response to an extended period of
coronal hole high speed stream (CH HSS) influences. Normal to
moderate levels were reached on 18-19 Oct.

Geomagnetic field activity reached G2 (Moderate) storm levels and
periods of G1 (Minor) storm levels on 18 Oct, and an early period of
G1 storm levels on 19 Oct due to influences from what was possibly
combined CMEs that left the Sun between 13-15 Oct. G1 storm levels
were also observed on 13 Oct due to CH HSS influences. An isolated
active period was observed on 15 Oct due to declining CH HSS
influence and . Quiet to unsettled levels were observed on 14, 16-17
Oct.

Forecast of Solar and Geomagnetic Activity
20 October - 15 November 2025

Solar activity is expected to be at moderate levels on 31 Oct - 15
Nov due to the return of Region 4246. Low levels are expected to
prevail on 20 Oct - 30 Oct, and 14-15 Nov.

No proton events are expected at geosynchronous orbit.

The greater than 2 MeV electron flux at geosynchronous orbit is
expected to reach high levels on 21-25 Oct, and 29 Oct - 15 Nov due
to responses from recurent CH HSS influences .

Geomagnetic field activity is expected to reach G1-G2
(Minor-Moderate) storm levels on 28-30 Oct and 08-09, and 15 Nov due
to recurrent CH HSS influences. Isolated active periods are expeced
on 20, 31 Oct, and 07 Nov also due to recurrent CH HSS activity.
Quiet to unsettled levels are expeced on the remaining days of the
outlook period.


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