:Product: Weekly Highlights and Forecasts
:Issued: 2026 May 25 0601 UTC
# Prepared by the US Dept. of Commerce, NOAA, Space Weather Prediction Center
# Product description and SWPC contact on the Web
# https://www.swpc.noaa.gov/content/subscription-services
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# Weekly Highlights and Forecasts
#
Highlights of Solar and Geomagnetic Activity
18 - 24 May 2026

Solar activity ranged from low to moderate levels. The largest flare
was an M2.3 (R1-Minor) at 22/1029 UTC from Region 4436 (N18, L=333,
class/area Dai/200 on 13 May). The region was also responsible for a
C8.3 and C9.5 flares on 21/1814 UTC and 21/1825 UTC, respectively.
This region was responsible for the majority of the C-class activity
until its rotation off the W limb on 21 May. On 23-24 May, the
majority of the C-class activity occurred from Region 4446 (S13,
L=141, class/area Dko/280 on 24 May). No Earth-directed CMEs were
observed during the period.

No proton events were observed at geosynchronous orbit.

The greater than 2 MeV electron flux at geosynchronous orbit reached
high levels on 18-24 May due to CH HSS influences. The highest flux
observed was 6,667 pfu at 18/1435 UTC.

Geomagnetic field activity ranged from quiet to active levels. Solar
wind parameters began the period in a slow decline from 560 km/s as
negative polarity CH HSS effects gradually diminished. At 19/0630
UTC, a small shock was observed increasing total field to 7-8 nT
while solar wind speed increased to near 625 km/s before beginning
to decline once again. This was likely the glancing effects from a
CME that left the Sun on 16 May. Solar wind speed continued to
decrease to nominal levels through 22 May. The geomagnetic field
reacted with quiet to active levels on 19 May. Quiet to unsettled
levels were observed on 18 May and 20-22 May. Quiet conditions
occurred on 23-24 May.

Forecast of Solar and Geomagnetic Activity
25 May - 20 June 2026

Solar activity is expected to be at low to moderate levels (R1-R2, Minor-Moderate) on 25 May through 07 Jun with the return of old
Region 4432 (N14, L=081). Mostly low levels with a chance for
M-class flares is expected from 08-20 Jun.

No proton events are expected at geosynchronous orbit.

The greater than 2 MeV electron flux at geosynchronous orbit is
expected to reach high levels on 25-27 May and 12-20 Jun due to CH
HSS influences.

Geomagnetic field activity is expected to be at unsettled to active
levels on 27-29 May, 04 Jun, 09 Jun, and 11-15 Jun due to recurrent
CH HSS activity. G2 (Moderate) storm conditions are likely on 11 Jun
and G1 (Minor) storming on 12 Jun due to CIR/CH HSS onset.


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