3-Day Forecast

Issued: 2025 Mar 18 1230 UTC
Prepared by the U.S. Dept. of Commerce, NOAA, Space Weather Prediction Center and processed by SpaceWeatherLive.com

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 Mar 18-Mar 20 2025 is 3 (.67below NOAA Scale levels).

NOAA Kp index breakdown

             Mar 18       Mar 19       Mar 20
00-03UT       3.33         3.00         3.67     
03-06UT       3.33         2.67         3.33     
06-09UT       2.33         2.00         2.67     
09-12UT       2.00         1.67         2.67     
12-15UT       2.00         2.33         2.33     
15-18UT       3.00         2.67         2.33     
18-21UT       3.33         3.00         2.00     
21-00UT       3.33         3.67         2.00     

Rationale

No G1 (Minor) or greater geomagnetic storms are expected. 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 Mar 18-Mar 20 2025

              Mar 18  Mar 19  Mar 20
S1 or greater    5%      5%      5%

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

Radio blackouts reaching the R1 levels were observed over the past 24 hours. The largest was at Mar 17 2025 1933 UTC.

Radio Blackout Forecast for Mar 18-Mar 20 2025

              Mar 18        Mar 19        Mar 20
R1-R2           50%           50%           50%
R3 or greater   10%           10%           10%

Rationale

A chance for M-class flares (R1-R2, Minor-Moderate) and a slight chance for X-class flares (R3, Strong) will persist through Mar 20.