3-Day Forecast

Issued: 2026 Mar 19 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 2 (below NOAA Scale levels).

The greatest expected 3 hr Kp for Mar 19-Mar 21 2026 is 6 (.33NOAA scale G2).

NOAA Kp index breakdown

             Mar 19       Mar 20       Mar 21
00-03UT       0.67         6.33 (G2)    4.67 (G1)
03-06UT       0.67         6.00 (G2)    6.33 (G2)
06-09UT       0.67         4.67 (G1)    5.67 (G2)
09-12UT       0.67         4.33         5.33 (G1)
12-15UT       3.33         3.33         4.33     
15-18UT       4.33         3.67         4.67 (G1)
18-21UT       5.33 (G1)    4.00         4.67 (G1)
21-00UT       6.00 (G2)    4.67 (G1)    4.33     

Rationale

G1-G2 (Minor-Moderate) geomagnetic storms are expected over 19-21 Mar due to combined effects of various potential CME arrivals and a negative polarity CH HSS.

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 19-Mar 21 2026

              Mar 19  Mar 20  Mar 21
S1 or greater    5%      5%     10%

Rationale

There is a slight chance for S1 (Minor) or greater solar radiation storms on 21 Mar due to potential accelerated particles ahead of the anticipated CME arrival.

C. NOAA Radio Blackout Activity and Forecast

No radio blackouts were observed over the past 24 hours.

Radio Blackout Forecast for Mar 19-Mar 21 2026

              Mar 19        Mar 20        Mar 21
R1-R2           35%           35%           35%
R3 or greater    5%            5%            5%

Rationale

There is a chance for R1-R2 (Minor-Moderate) radio blackouts, with a slight chance for R3 (Strong) events, on 19-21 Mar, primarily due to the flaring potential of Region 4392.