:Product: Forecast Discussion
:Issued: 2026 Sep 21 0030 UTC
# Prepared by the U.S. Dept. of Commerce, NOAA, Space Weather Prediction Center
#
Solar Activity

.24 hr Summary...
Solar activity reached low levels with a C1.1 flare at 20/0518 UTC from 
new Region 4535 (N12E73, Hrx/alpha), and a C3.7/1f flare at 20/2234 UTC
from Region 4534 (N11W08, Dro/beta). Regions 4532 (S06W54, Bxo/beta) and
4534 exhibited minor growth this period while the remaining regions were
stable. No Earth-directed CMEs were detected in available coronagraph
imagery.

.Forecast...
Solar activity is expected to be at very low levels on 21-23 Sep.

Energetic Particle

.24 hr Summary...
The greater than 2 MeV electron flux was at normal to moderate levels.
The greater than 10 MeV proton flux was steady at background levels.

.Forecast...
The greater than 2 MeV electron flux is expected to continue at normal
to moderate levels on 21-23 Sep. The greater than 10 MeV proton flux is
expected to continue at background levels through 23 Sep.

Solar Wind

.24 hr Summary...
The solar wind environment remained undisturbed over the past 24 hours.
Total magnetic field strength averaged around 5 nT, and the north-south
(Bz) component varied between +3/-4 nT. Solar wind speeds gradually
decreased from a peak of around 430 km/s to 370 km/s by the end of the
reporting period. The phi angle was predominately negative throughout
the day.

.Forecast...
Ambient solar wind conditions are expected to prevail over 21-23 Sep.

Geospace

.24 hr Summary...
The geomagnetic field was at quiet to unsettled levels.

.Forecast...
Mostly quiet geomagnetic field conditions are expected to prevail over
21-23 Sep.