Product: 3-Day Forecast
- Issued: 2026 Sep 16 0030 UTC
Prepared by the U.S. Dept. of Commerce, NOAA, Space Weather Prediction Center.
Geomagnetic Activity Observation and Forecast
The greatest observed 3 hr Kp over the past 24 hours was 3 (below NOAA Scale levels). The greatest expected 3 hr Kp for Sep 16-Sep 18 2026 is 4.67 (NOAA Scale G1).
| Sep 16 | Sep 17 | Sep 18 | |
|---|---|---|---|
| 00-03UT | 3.67 | 4.00 | 3.67 |
| 03-06UT | 3.33 | 4.67 (G1) | 2.00 |
| 06-09UT | 3.00 | 3.67 | 2.00 |
| 09-12UT | 2.67 | 3.33 | 2.67 |
| 12-15UT | 3.00 | 3.33 | 2.67 |
| 15-18UT | 3.33 | 3.33 | 2.67 |
| 18-21UT | 3.67 | 3.33 | 2.67 |
| 21-00UT | 4.67 (G1) | 3.33 | 3.00 |
Rationale: G1 (Minor) geomagnetic storms are likely on 16-17 Sep due to the anticipated effect of -CH HSS and CMEs glancing blow.
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.
| Sep 16 | Sep 17 | Sep 18 | |
|---|---|---|---|
| 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.
Radio Blackout Activity and Forecast
No radio blackouts were observed over the past 24 hours.
| Sep 16 | Sep 17 | Sep 18 | |
|---|---|---|---|
| R1-R2 | 5% | 5% | 5% |
| R3 or greater | 1% | 1% | 1% |
Rationale: No R1 (Minor) or greater radio blackouts are expected. No significant active region flare activity is forecast.
Space Weather Overview
Credits
Space Weather Images and Information (excluded from copyright) courtesy of:
NOAA / NWS Space Weather Prediction Center
Mauna Loa Solar Observatory (HAO/NCAR)
SOHO (ESA & NASA)
Powered by Space Weather PHP script by Mike Challis of Long Beach Weather.
Additions by Ken True of Saratoga Weather and Jerry Wilkins of Southeast Lincoln Weather.