3-Day Forecast

Issued: 2025 Dec 05 0030 UTC
Prepared by the U.S. Dept. of Commerce, NOAA, Space Weather Prediction Center and processed by SpaceWeatherLive.com

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 05-Dec 07 2025 is 5 (.00NOAA scale G1).

NOAA Kp index breakdown

             Dec 05       Dec 06       Dec 07
00-03UT       3.67         3.67         2.67     
03-06UT       3.67         2.00         2.00     
06-09UT       3.67         2.00         2.33     
09-12UT       3.33         2.67         2.33     
12-15UT       3.33         2.67         2.33     
15-18UT       3.33         2.67         3.67     
18-21UT       3.33         2.67         5.00 (G1)
21-00UT       3.33         3.00         4.00     

Rationale

G1 (Minor) geomagnetic storms are likely on 07 Dec due to a combination of negative polarity CH HSS influences and glancing effects from the 04 Dec CME.

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 05-Dec 07 2025

              Dec 05  Dec 06  Dec 07
S1 or greater   15%     15%     15%

Rationale

There is a slight chance for S1 (Minor) solar radiation storm conditions on 05-07 Dec.

C. NOAA Radio Blackout Activity and Forecast

Radio blackouts reaching the R2 levels were observed over the past 24 hours. The largest was at Dec 04 2025 0250 UTC.

Radio Blackout Forecast for Dec 05-Dec 07 2025

              Dec 05        Dec 06        Dec 07
R1-R2           75%           75%           75%
R3 or greater   25%           25%           25%

Rationale

R1-R2 (Minor-Moderate) radio blackouts are expected, with a chance for R3 (Strong) or greater events, on 05-07 Dec.