:Product: Report of Solar-Geophysical Activity
:Issued: 2026 Sep 21 2315 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 264 Issued at 2200Z on 21 Sep 2026

IA.  Analysis of Solar Active Regions and Activity from 20/2100Z to
21/2100Z: Solar activity has been at low levels for the past 24 hours.
There are currently 6 numbered sunspot regions on the disk.
IB.  Solar Activity Forecast: Solar activity is likely to be low with a
slight chance for an M-class flare on days one, two, and three (22 Sep,
23 Sep, 24 Sep).

IIA.  Geophysical Activity Summary 20/2100Z to 21/2100Z: The geomagnetic
field has been at NA levels for the past 24 hours. Solar wind speed
reached a peak of 369 km/s at 20/2356 UTC. Total IMF reached 4 nT at
21/1857 UTC. The maximum southward component of Bz reached -3 nT at
21/2118 UTC. Electrons greater than 2 MeV at geosynchronous orbit
reached a peak level of 585 pfu.
IIB.  Geophysical Activity Forecast: The geomagnetic field is expected
to be at quiet levels on day one (22 Sep), quiet to active levels on day
two (23 Sep) and quiet to minor storm levels on day three (24 Sep).

III.  Event probabilities 22 Sep-24 Sep
Class M    10/10/10
Class X    01/01/01
Proton     01/01/01
PCAF       green

IV.  Penticton 10.7 cm Flux
Observed           21 Sep 104
Predicted   22 Sep-24 Sep 105/105/100
90 Day Mean        21 Sep 125

V.  Geomagnetic A Indices
Observed Afr/Ap 20 Sep  006/006
Estimated Afr/Ap 21 Sep  003/003
Predicted Afr/Ap 22 Sep-24 Sep  006/005-011/012-020/025

VI.  Geomagnetic Activity Probabilities 21 Sep-23 Sep
A.  Middle Latitudes
Active                10/20/35
Minor Storm           05/10/15
Major-severe storm    01/05/05
B.  High Latitudes
Active                15/15/20
Minor Storm           15/20/20
Major-severe storm    15/35/20