408
FXXX10 KWNP 251231
DAYTDF

:Product: 3-Day Forecast
:Issued: 2026 Sep 25 1230 UTC
# Prepared by the US Dept. of Commerce, NOAA, Space Weather Prediction Center
# Product description and SWPC contact on the Web
# http://www.swpc.noaa.gov/wwire.html
#
#             3-Day Forecast
#
A. NOAA Geomagnetic Activity Observation and Forecast

The greatest observed 3 hr Kp over the past 24 hours was 4 (below NOAA
Scale levels).
The greatest expected 3 hr Kp for Sep 25-Sep 27 2026 is 3.67 (below NOAA
Scale levels).

NOAA Kp index breakdown Sep 25-Sep 27 2026

             Sep 25       Sep 26       Sep 27
00-03UT       3.67         3.00         2.33
03-06UT       3.67         3.67         2.67
06-09UT       3.00         2.67         2.33
09-12UT       2.67         2.00         2.33
12-15UT       2.33         1.67         2.00
15-18UT       3.00         2.33         2.00
18-21UT       3.33         2.33         2.00
21-00UT       3.00         2.67         2.00

Rationale: No G1 (Minor) or greater geomagnetic storms are expected as
positive polarity coronal hole high speed stream influences are
anticipated to continue and wane through 27 Sep.

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 Sep 25-Sep 27 2026

              Sep 25  Sep 26  Sep 27
S1 or greater    1%      1%      1%

Rationale: No S1 (Minor) or greater solar radiation storms are expected.
through 27 Sep.

C. NOAA Radio Blackout Activity and Forecast

No radio blackouts were observed over the past 24 hours.

Radio Blackout Forecast for Sep 25-Sep 27 2026

              Sep 25        Sep 26        Sep 27
R1-R2           20%           20%           20%
R3 or greater    1%            1%            1%

Rationale: There is a slight chance for R1-R2 (Minor-Moderate) radio
blackouts through 27 Sep.