:Product: Report of Solar-Geophysical Activity
:Issued: 2026 Aug 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 230 Issued at 2200Z on 18 Aug 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 Aug, 20 Aug,
21 Aug).

IIA.  Geophysical Activity Summary 17/2100Z to 18/2100Z: The geomagnetic
field has been at quiet to minor storm levels for the past 24 hours.
Solar wind speed reached a peak of 578 km/s. Total IMF reached 15 nT.
The maximum southward component of Bz reached -11 nT.  Electrons greater
than 2 MeV at geosynchronous orbit reached a peak level of 349 pfu.
IIB.  Geophysical Activity Forecast: The geomagnetic field is expected
to be at quiet to minor storm levels on day one (19 Aug) and quiet to
active levels on days two and three (20 Aug, 21 Aug).

III.  Event probabilities 19 Aug-21 Aug
Class M    35/35/35
Class X    05/05/05
Proton     05/05/05
PCAF       green

IV.  Penticton 10.7 cm Flux
Observed           18 Aug 125
Predicted   19 Aug-21 Aug 125/125/120
90 Day Mean        18 Aug 132

V.  Geomagnetic A Indices
Observed Afr/Ap 17 Aug  019/011
Estimated Afr/Ap 18 Aug  018/027
Predicted Afr/Ap 19 Aug-21 Aug  019/020-014/015-011/012

VI.  Geomagnetic Activity Probabilities 19 Aug-21 Aug
A.  Middle Latitudes
Active                40/35/30
Minor Storm           25/15/10
Major-severe storm    05/01/01
B.  High Latitudes
Active                10/15/15
Minor Storm           30/35/30
Major-severe storm    55/40/35