:Product: 3-Day Forecast
:Issued: 2026 May 29 1230 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 4 (below NOAA
Scale levels).
The greatest expected 3 hr Kp for May 29-May 31 2026 is 4.00 (below NOAA
Scale levels).

NOAA Kp index breakdown May 29-May 31 2026

             May 29       May 30       May 31
00-03UT       2.67         2.33         3.00     
03-06UT       3.00         2.00         2.33     
06-09UT       2.33         1.33         2.33     
09-12UT       3.67         1.33         1.67     
12-15UT       2.00         2.67         3.33     
15-18UT       2.33         2.33         2.67     
18-21UT       2.67         3.00         4.00     
21-00UT       3.67         3.00         3.67     

Rationale: No G1 (Minor) or greater geomagnetic storms are expected.  

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 May 29-May 31 2026

              May 29  May 30  May 31
S1 or greater    5%      5%      5%

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

C. NOAA Radio Blackout Activity and Forecast

Radio blackouts reaching the R1 levels were observed over the past 24
hours. The largest was at May 29 2026 0704 UTC.

Radio Blackout Forecast for May 29-May 31 2026

              May 29        May 30        May 31
R1-R2           40%           40%           40%
R3 or greater    5%            5%            5%

Rationale: There is a chance for R1-R2 (Minor-Moderate) radio blackouts
through 31 May.