:Product: Report of Solar-Geophysical Activity
:Issued: 2026 May 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 151 Issued at 2200Z on 31 May 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 8 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 and two (01 Jun, 02 Jun) and
expected to be low with a slight chance for an M-class flare on day
three (03 Jun).

IIA.  Geophysical Activity Summary 30/2100Z to 31/2100Z: The geomagnetic
field has been at quiet to active levels for the past 24 hours. Solar
wind speed reached a peak of 566 km/s at 30/2104Z. Total IMF reached 8
nT at 30/2228Z. The maximum southward component of Bz reached -7 nT at
30/2125Z.  Electrons greater than 2 MeV at geosynchronous orbit reached
a peak level of 475 pfu.
IIB.  Geophysical Activity Forecast: The geomagnetic field is expected
to be at quiet to active levels on days one and three (01 Jun, 03 Jun)
and quiet to unsettled levels on day two (02 Jun).

III.  Event probabilities 01 Jun-03 Jun
Class M    25/25/20
Class X    05/05/01
Proton     05/05/01
PCAF       green

IV.  Penticton 10.7 cm Flux
Observed           31 May 136
Predicted   01 Jun-03 Jun 136/134/130
90 Day Mean        31 May 125

V.  Geomagnetic A Indices
Observed Afr/Ap 30 May  013/015
Estimated Afr/Ap 31 May  010/012
Predicted Afr/Ap 01 Jun-03 Jun  009/010-007/008-012/014

VI.  Geomagnetic Activity Probabilities 01 Jun-03 Jun
A.  Middle Latitudes
Active                30/20/35
Minor Storm           10/05/15
Major-severe storm    01/01/01
B.  High Latitudes
Active                15/15/15
Minor Storm           30/30/35
Major-severe storm    40/25/40