:Product: 3-Day Forecast
:Issued: 2026 Oct 10 1230 UTC
# Prepared by the U.S. Dept. of Commerce, NOAA, Space Weather Prediction Center
#
A. NOAA Geomagnetic Activity Observation and Forecast

The greatest observed 3 hr Kp over the past 24 hours was 3 (below NOAA
Scale levels).
The greatest expected 3 hr Kp for Oct 10-Oct 12 2026 is 5.67 (NOAA Scale
G2).

NOAA Kp index breakdown Oct 10-Oct 12 2026

             Oct 10       Oct 11       Oct 12
00-03UT       2.33         2.67         5.33 (G1)    
03-06UT       3.00         2.67         5.67 (G2)    
06-09UT       3.00         3.33         5.33 (G1)    
09-12UT       2.33         3.33         4.33         
12-15UT       3.33         3.67         3.67         
15-18UT       3.67         4.00         3.67         
18-21UT       4.00         4.67 (G1)    3.67         
21-00UT       4.67 (G1)    4.67 (G1)    3.67         

Rationale: G1 (Minor) geomagnetic storming conditions are expected late
on 10 Oct and late on 11 Oct, with G1-G2 (Minor-Moderate) expected on 12
Oct, due to the anticipated arrivals of several different CMEs with some
potential negative polarity coronal hole high speed stream influences.

B. NOAA Solar Radiation Activity Observation and Forecast

Solar radiation, as observed by NOAA GOES-18 over the past 24 hours, was
below S-scale storm level thresholds.

Solar Radiation Storm Forecast for Oct 10-Oct 12 2026

              Oct 10  Oct 11  Oct 12
S1 or greater   10%     10%     10%

Rationale: There is a slight chance for S1 (Minor) or greater solar
radiation storms through 12 Oct, due primarily to the flaring potential
of Region 4549 and the activity observed off the west limb.

C. NOAA Radio Blackout Activity and Forecast

Radio blackouts reaching the R1 levels were observed over the past 24
hours. The largest was at 09/1409Z UTC.

Radio Blackout Forecast for Oct 10-Oct 12 2026

              Oct 10        Oct 11        Oct 12
R1-R2           55%           55%           55%
R3 or greater   10%           10%           10%

Rationale: R1-R2 (Minor-Moderate) radio blackouts are likely, with a
slight chance for R3 (Strong) or greater events, through 12 Oct, due
primarily to the flaring potential of Region 4549 and the activity
observed off the west limb.