905
FXXX10 KWNP 261231
DAYTDF

:Product: 3-Day Forecast
:Issued: 2026 Sep 26 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 26-Sep 28 2026 is 4.00 (below NOAA
Scale levels).

NOAA Kp index breakdown Sep 26-Sep 28 2026

             Sep 26       Sep 27       Sep 28
00-03UT       3.33         2.67         1.67
03-06UT       4.00         3.00         2.00
06-09UT       3.67         2.67         1.67
09-12UT       2.67         2.67         1.67
12-15UT       2.00         2.00         1.67
15-18UT       1.67         1.67         0.67
18-21UT       1.67         1.67         0.67
21-00UT       2.33         2.00         1.67

Rationale: No G1 (Minor) or greater geomagnetic storms are expected
through 28 Sep as no significant transient or recurrent solar wind
features are forecast.

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 26-Sep 28 2026

              Sep 26  Sep 27  Sep 28
S1 or greater    1%      1%      1%

Rationale: No S1 (Minor) or greater solar radiation storms are expected.
No significant active region activity favorable for radiation storm
production is forecast.

C. NOAA Radio Blackout Activity and Forecast

No radio blackouts were observed over the past 24 hours.

Radio Blackout Forecast for Sep 26-Sep 28 2026

              Sep 26        Sep 27        Sep 28
R1-R2           10%           10%            5%
R3 or greater    1%            1%            1%

Rationale: There is a slight chance for R1-R2 (Minor-Moderate) radio
blackouts through 28 Sep.