:Product: Weekly Highlights and Forecasts
:Issued: 2026 Mar 16 0302 UTC
# Prepared by the US Dept. of Commerce, NOAA, Space Weather Prediction Center
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# Weekly Highlights and Forecasts
#
Highlights of Solar and Geomagnetic Activity
09 - 15 March 2026

Solar activity was at low to moderate levels with a total of 37
C-class flares and 2 M-class flares observed. The largest flares of
the period were an M1.2 flare on 13/0955 UTC from Region 4384 (N10,
L=150, class/area Eho/300 on 03 Mar), a C8.9/1n flare on 13/2023
from Region 4392 (S15, L=017, class/area Cso/170 on 15 Mar), and an
M1.0/Sf flare on 15/0939 UTC from Region 4392. The most active
region of the period was Region 4381 (N08, L=173, class/area Eao/220
on 03 Mar) which produced a long duration C8.0 flare on 13/1518 UTC
in addition to 11 other weak C-class events.

No proton events were observed at geosynchronous orbit.

The greater than 2 MeV electron flux at geosynchronous orbit reached
high levels on 09 - 13 Mar and 15 Mar with a peak flux of 2,940 pfu
observed at 12/1545 UTC. Normal to moderate levels were observed on
14 Mar.

Geomagnetic field activity ranged from quiet to G2 (Moderate) storm
levels throughout the 09-15 Mar period. The week began at quiet to
unsettled levels on 09 Mar, with active conditions observed on 10-11
Mar due to the influence of a negative polarity coronal hole high
speed stream (CH HSS). Conditions returned to mostly quiet to
unsettled levels by 12 Mar. Activity intensified midday on 13 Mar,
reaching G1 (Minor) to G2 (Moderate) storm levels following the
onset of a positive polarity CH HSS. These storming levels continued
through the first half of 14 Mar before waning to unsettled and
active levels later in the day. On 15 Mar, the field reached active
levels early in the period, followed by a return to quiet and
unsettled conditions as positive polarity CH HSS effects gradually
diminished.

Solar wind parameters reflected the influence of two distinct CH HSS
regimes during the period. The week began under the influence of a
negative polarity CH HSS, with solar wind speeds initially ranging
between 450-500 km/s before gradually declining to ambient levels
near 400 km/s by 12 Mar. Total magnetic field (Bt) remained mostly
around 6 nT during this interval, while the North-South (Bz)
component saw periodic southward deflections to -7 nT. A solar
sector boundary crossing (SSBC) occurred early on 13 Mar, indicated
by a shift in the phi angle from the towards to away sector. This
was immediately followed by the onset of a more powerful positive
polarity CH HSS. Solar wind speeds rose sharply from 400 km/s to a
peak of 725 km/s on 14 Mar. During this period, Bt reached 13 nT and
the Bz component reached a maximum southward deflection of -10 nT.
By 15 Mar, solar wind speeds began a slow decline but remained
elevated near 600 km/s through the end of the period.

Forecast of Solar and Geomagnetic Activity
16 March - 11 April 2026

Solar activity is expected to be at low levels, with a slight chance
for M-class (R1-R2/Minor-Moderate) flares throughout the outlook
period. Elevated probabilities are related to the flare potential of
both currently observed spot groups as well as the potential from
returning regions.

No proton events are expected at geosynchronous orbit.

The greater than 2 MeV electron flux at geosynchronous orbit is
expected to be at high levels on 16-20, 22-30 Mar, 04-09, and 11 Apr
due to the influence from multiple, recurrent, CH HSSs. The
remainder of the outlook period is likely to be at normal to
moderate levels.

Geomagnetic field activity levels are likely to reach G1 (Minor)
geomagnetic storm levels on 22 Mar, 04 Apr, 09 Apr, and 11 Apr due
to CH HSS influences. G2 (Moderate) geomagnetic storm levels are
likely on 11 Mar and 10 Apr due to CH HSS influences. Unsettled to
active levels are likely on 16-18, 20, 23-27, 30-31 Mar and 03 and
05-07 Apr. All elevated levels of geomagnetic activity are
associated with the anticipated influence of multiple, recurrent, CH
HSSs. The remainder of the outlook period is likely to be at mostly
quiet levels.


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