630
FXXX10 KWNP 301231
DAYTDF

:Product: 3-Day Forecast
:Issued: 2026 Sep 30 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 1 (below NOAA
Scale levels).
The greatest expected 3 hr Kp for Sep 30-Oct 02 2026 is 4.67 (NOAA Scale
G1).

NOAA Kp index breakdown Sep 30-Oct 02 2026

             Sep 30       Oct 01       Oct 02
00-03UT       1.00         1.67         2.33
03-06UT       1.00         1.33         2.67
06-09UT       0.33         1.33         2.67
09-12UT       1.33         1.33         3.33
12-15UT       1.33         1.33         3.67
15-18UT       1.00         1.33         4.67 (G1)
18-21UT       1.00         1.67         4.00
21-00UT       1.67         1.67         3.33

Rationale: G1 (Minor) geomagnetic storms are likely on 02 Oct due to
anticipated glancing influences from the 28 Sep CME near Earth.

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 30-Oct 02 2026

              Sep 30  Oct 01  Oct 02
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 30-Oct 02 2026

              Sep 30        Oct 01        Oct 02
R1-R2           15%           15%           10%
R3 or greater    1%            1%            1%

Rationale: There is a slight chance for R1-R2 (Minor-Moderate) radio
blackouts through 02 Oct.