:Product: Report of Solar-Geophysical Activity
:Issued: 2026 Oct 18 2200 UTC
# Prepared jointly by the U.S. Dept. of Commerce, NOAA,
# Space Weather Prediction Center and the U.S. Air Force.
#
Joint USAF/NOAA Solar Geophysical Activity Report and Forecast
SDF Number 291 Issued at 2200Z on 18 Oct 2026

IA.  Analysis of Solar Active Regions and Activity from 17/2100Z to
18/2100Z: Solar activity has been at low levels for the past 24 hours.
There are currently 4 numbered sunspot regions on the disk.
IB.  Solar Activity Forecast: Solar activity is expected to be low with
a chance for M-class flares on days one, two, and three (19 Oct, 20 Oct,
21 Oct).

IIA.  Geophysical Activity Summary 17/2100Z to 18/2100Z: The geomagnetic
field has been at quiet levels for the past 24 hours. Solar wind speed
reached a peak of 540 km/s at 18/0421Z. Total IMF reached 8 nT at
17/2330Z. The maximum southward component of Bz reached -5 nT at
18/0144Z. Electrons greater than 2 MeV at geosynchronous orbit reached a
peak level of 442 pfu.
IIB.  Geophysical Activity Forecast: The geomagnetic field is expected
to be at quiet to minor storm levels on day one (19 Oct), unsettled to
minor storm levels on day two (20 Oct) and quiet to active levels on day
three (21 Oct).

III.  Event probabilities 19 Oct-21 Oct
Class M    25/25/25
Class X    05/05/05
Proton     05/05/05
PCAF       green

IV.  Penticton 10.7 cm Flux
Observed           18 Oct 137
Predicted   19 Oct-21 Oct 135/135/125
90 Day Mean        18 Oct 117

V.  Geomagnetic A Indices
Observed Afr/Ap 17 Oct  004/006
Estimated Afr/Ap 18 Oct  006/006
Predicted Afr/Ap 19 Oct-21 Oct  015/018-017/022-013/015

VI.  Geomagnetic Activity Probabilities 19 Oct-21 Oct
A.  Middle Latitudes
Active                35/40/30
Minor Storm           05/15/10
Major-severe storm    01/01/01
B.  High Latitudes
Active                15/15/15
Minor Storm           20/20/20
Major-severe storm    20/20/25