:Product: 3-Day Forecast
:Issued: 2025 Dec 12 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 5 (NOAA Scale
G1).
The greatest expected 3 hr Kp for Dec 12-Dec 14 2025 is 4.33 (below NOAA
Scale levels).

NOAA Kp index breakdown Dec 12-Dec 14 2025

             Dec 12       Dec 13       Dec 14
00-03UT       4.00         4.33         3.67     
03-06UT       4.00         3.67         3.00     
06-09UT       3.00         2.33         2.67     
09-12UT       3.67         1.67         2.67     
12-15UT       3.33         2.00         2.67     
15-18UT       3.00         2.67         2.00     
18-21UT       3.33         3.33         2.00     
21-00UT       3.67         3.67         2.67     

Rationale: No G1 (Minor) or greater geomagnetic storms are expected. 

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 Dec 12-Dec 14 2025

              Dec 12  Dec 13  Dec 14
S1 or greater   10%      5%      1%

Rationale: There is a slight chance for S1 (Minor) or greater solar
radiation storms 12-14 Dec. Little significant active region activity
favorable for radiation storm production is forecast.

C. NOAA Radio Blackout Activity and Forecast

Radio blackouts reaching the R1 levels were observed over the past 24
hours. The largest was at Dec 12 2025 0505 UTC.

Radio Blackout Forecast for Dec 12-Dec 14 2025

              Dec 12        Dec 13        Dec 14
R1-R2           65%           60%           55%
R3 or greater   10%            5%            5%

Rationale: R1-R2 (Minor-Moderate) radio blackouts are likely, with a
slight chance of R3 (Strong) or greater events, on 12-14 Dec.