Subj : 3 Day Space Weather Forecast
To   : All
From : Sean Dennis
Date : Tue Dec 30 2025 12:19 am

:Product: 3-Day Forecast
:Issued: 2025 Dec 30 0030 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 Dec 30-Jan 01 2026 is 5.00 (NOAA Scale
G1).

NOAA Kp index breakdown Dec 30-Jan 01 2026

             Dec 30       Dec 31       Jan 01
00-03UT       1.33         1.67         5.00 (G1)
03-06UT       1.33         1.67         4.33
06-09UT       1.33         2.00         3.67
09-12UT       1.33         2.00         3.33
12-15UT       1.67         2.33         3.33
15-18UT       2.00         2.67         4.00
18-21UT       2.67         3.33         3.67
21-00UT       3.00         4.33         3.33

Rationale: No G1 (Minor) or greater geomagnetic storms are expected
through 31 Dec. G1 (Minor) geomagnetic storms are likely on 01 Jan due
to recurrent solar wind features combined with potential transient
features.

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 30-Jan 01 2026

              Dec 30  Dec 31  Jan 01
S1 or greater   10%     10%     10%

Rationale: There is a slight chance for a flux above the S1 (Minor) or
greater threshold due to the flaring potential of the active regions on
the visible solar disk.

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 29 2025 0651 UTC.

Radio Blackout Forecast for Dec 30-Jan 01 2026

              Dec 30        Dec 31        Jan 01
R1-R2           55%           55%           55%
R3 or greater   10%           10%           10%

Rationale: R1/R2 (Minor-Moderate) radio blackouts are likely on 30-31
Dec and 01 Jan due to the flare potential of the current active regions.
There is a slight chance for isolated R3 (Strong) events during the
3-day period.



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