:Product: Report of Solar-Geophysical Activity
:Issued: 2026 Mar 31 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 90 Issued at 2200Z on 31 Mar 2026

IA.  Analysis of Solar Active Regions and Activity from 30/2100Z to
31/2100Z: Solar activity has been at low levels for the past 24 hours.
There are currently 10 numbered sunspot regions on the disk.
IB.  Solar Activity Forecast: Solar activity is likely to be moderate
with a slight chance for an X-class flare on days one, two, and three
(01 Apr, 02 Apr, 03 Apr).

IIA.  Geophysical Activity Summary 30/2100Z to 31/2100Z: The geomagnetic
field has been at quiet to unsettled levels for the past 24 hours. Solar
wind speed reached a peak of 509 km/s at 31/0605Z. Total IMF reached 6
nT at 30/2106Z. The maximum southward component of Bz reached -4 nT at
31/0735Z.  Electrons greater than 2 MeV at geosynchronous orbit reached
a peak level of 1380 pfu.
IIB.  Geophysical Activity Forecast: The geomagnetic field is expected
to be at quiet to minor storm levels on days one and two (01 Apr, 02
Apr) and unsettled to active levels on day three (03 Apr). Protons have
a slight chance of crossing threshold on days one, two, and three (01
Apr, 02 Apr, 03 Apr).

III.  Event probabilities 01 Apr-03 Apr
Class M    55/55/55
Class X    20/20/20
Proton     20/20/20
PCAF       green

IV.  Penticton 10.7 cm Flux
Observed           31 Mar 141
Predicted   01 Apr-03 Apr 145/145/140
90 Day Mean        31 Mar 139

V.  Geomagnetic A Indices
Observed Afr/Ap 30 Mar  011/012
Estimated Afr/Ap 31 Mar  016/030
Predicted Afr/Ap 01 Apr-03 Apr  019/024-016/023-014/018

VI.  Geomagnetic Activity Probabilities 01 Apr-03 Apr
A.  Middle Latitudes
Active                40/40/40
Minor Storm           25/25/15
Major-severe storm    05/05/01
B.  High Latitudes
Active                10/10/10
Minor Storm           25/25/25
Major-severe storm    60/60/50