| TYPE | RADIO BLACKOUT | SOLAR STORM | GEO STORM |
|---|---|---|---|
| SCALE | 1-2: 10%, 3-5: 35% | 10% | 2 |
| TEXT | None | S1 or < | moderate |
| TYPE | RADIO BLACKOUT | SOLAR STORM | GEO STORM |
|---|---|---|---|
| SCALE | 0 | 0 | 0 |
| TEXT | none | none | none |
| TYPE | RADIO BLACKOUT | SOLAR STORM | GEO STORM |
|---|---|---|---|
| SCALE | 1-2: 10%, 3-5: 10% | 10% | 2 |
| TEXT | None | S1 or < | moderate |
:Product: 3-Day Forecast
:Issued: 2026 Mar 19 0030 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 2 (below NOAA
Scale levels).
The greatest expected 3 hr Kp for Mar 19-Mar 21 2026 is 6.33 (NOAA Scale
G2).
NOAA Kp index breakdown Mar 19-Mar 21 2026
Mar 19 Mar 20 Mar 21
00-03UT 1.67 6.33 (G2) 4.33
03-06UT 2.00 6.00 (G2) 6.33 (G2)
06-09UT 2.33 4.67 (G1) 5.67 (G2)
09-12UT 3.00 4.33 5.00 (G1)
12-15UT 3.33 4.33 5.00 (G1)
15-18UT 4.33 4.00 4.67 (G1)
18-21UT 5.33 (G1) 4.00 4.67 (G1)
21-00UT 6.00 (G2) 3.33 4.33
Rationale: G1-G2 (Minor-Moderate) geomagnetic storms are expected over
19-21 Mar due to arrival of the 16 and 18 Mar CMEs alongside an
anticipated solar sector boundary crossing.
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 10% 10% 10%
Rationale: There is a slight chance for S1 (Minor) or greater solar
radiation storms on 19-21 Mar due to the potential of CME shock
influences.
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 18 2026 0839 UTC.
Radio Blackout Forecast for Mar 19-Mar 21 2026
Mar 19 Mar 20 Mar 21
R1-R2 35% 35% 35%
R3 or greater 10% 10% 10%
Rationale: There is a chance for R1-R2 (Minor-Moderate) radio blackouts,
with a slight chance for R3 (Strong) events through 21 Mar due
predominantly to the flaring potential of Region 4392.
Updated last 2026/03/19 02:30 UTC
-------------------
Product ID: A30F
Issued: 2026-03-18 21:14:07.740
Message Follows:
Space Weather Message Code: WATA30
Serial Number: 265
Issue Time: 2026 Mar 18 2114 UTC
WATCH: Geomagnetic Storm Category G2 Predicted
Highest Storm Level Predicted by Day:
Mar 19: G2 (Moderate) Mar 20: G2 (Moderate) Mar 21: G2 (Moderate)
THIS SUPERSEDES ANY/ALL PRIOR WATCHES IN EFFECT
NOAA Space Weather Scale descriptions can be found at
www.swpc.noaa.gov/noaa-scales-explanation
Potential Impacts: Area of impact primarily poleward of 55 degrees Geomagnetic Latitude.
Induced Currents - Power grid fluctuations can occur. High-latitude power systems may experience voltage alarms.
Spacecraft - Satellite orientation irregularities may occur; increased drag on low Earth-orbit satellites is possible.
Radio - HF (high frequency) radio propagation can fade at higher latitudes.
Aurora - Aurora may be seen as low as New York to Wisconsin to Washington state.
-------------------
Product ID: BHIS
Issued: 2026-03-18 09:03:34.557
Message Follows:
Space Weather Message Code: SUM10R
Serial Number: 902
Issue Time: 2026 Mar 18 0903 UTC
SUMMARY: 10cm Radio Burst
Begin Time: 2026 Mar 18 0833 UTC
Maximum Time: 2026 Mar 18 0835 UTC
End Time: 2026 Mar 18 0839 UTC
Duration: 6 minutes
Peak Flux: 229 sfu
Latest Penticton Noon Flux: 111 sfu
Description: A 10cm radio burst indicates that the electromagnetic burst associated with a solar flare at the 10cm wavelength was double or greater than the initial 10cm radio background. This can be indicative of significant radio noise in association with a solar flare. This noise is generally short-lived but can cause interference for sensitive receivers including radar, GPS, and satellite communications.
-------------------
Product ID: TIIA
Issued: 2026-03-18 08:59:48.527
Message Follows:
Space Weather Message Code: ALTTP2
Serial Number: 1470
Issue Time: 2026 Mar 18 0859 UTC
ALERT: Type II Radio Emission
Begin Time: 2026 Mar 18 0840 UTC
Estimated Velocity: 866 km/s
Description: Type II emissions occur in association with eruptions on the sun and typically indicate a coronal mass ejection is associated with a flare event.
-------------------
Product ID: EF3A
Issued: 2026-03-18 04:59:44.273
Message Follows:
Space Weather Message Code: ALTEF3
Serial Number: 3650
Issue Time: 2026 Mar 18 0459 UTC
CONTINUED ALERT: Electron 2MeV Integral Flux exceeded 1000pfu
Continuation of Serial Number: 3649
Begin Time: 2026 Mar 15 1630 UTC
Yesterday Maximum 2MeV Flux: 2233 pfu
Potential Impacts: Satellite systems may experience significant charging resulting in increased risk to satellite systems.
-------------------
Product ID: A30F
Issued: 2026-03-17 18:36:37.167
Message Follows:
Space Weather Message Code: WATA30
Serial Number: 264
Issue Time: 2026 Mar 17 1836 UTC
WATCH: Geomagnetic Storm Category G2 Predicted
Highest Storm Level Predicted by Day:
Mar 18: None (Below G1) Mar 19: G2 (Moderate) Mar 20: G1 (Minor)
THIS SUPERSEDES ANY/ALL PRIOR WATCHES IN EFFECT
Comment: CME influences are likely on 19 Mar with any effects continuing, but weakening, into 20 Mar.
NOAA Space Weather Scale descriptions can be found at
www.swpc.noaa.gov/noaa-scales-explanation
Potential Impacts: Area of impact primarily poleward of 55 degrees Geomagnetic Latitude.
Induced Currents - Power grid fluctuations can occur. High-latitude power systems may experience voltage alarms.
Spacecraft - Satellite orientation irregularities may occur; increased drag on low Earth-orbit satellites is possible.
Radio - HF (high frequency) radio propagation can fade at higher latitudes.
Aurora - Aurora may be seen as low as New York to Wisconsin to Washington state.
-------------------
Product ID: EF3A
Issued: 2026-03-17 14:03:49.470
Message Follows:
Space Weather Message Code: ALTEF3
Serial Number: 3649
Issue Time: 2026 Mar 17 1403 UTC
CONTINUED ALERT: Electron 2MeV Integral Flux exceeded 1000pfu
Continuation of Serial Number: 3648
Begin Time: 2026 Mar 15 1630 UTC
Yesterday Maximum 2MeV Flux: 2213 pfu
Potential Impacts: Satellite systems may experience significant charging resulting in increased risk to satellite systems.
-------------------
Product ID: A30F
Issued: 2026-03-16 21:08:59.560
Message Follows:
Space Weather Message Code: WATA30
Serial Number: 264
Issue Time: 2026 Mar 16 2108 UTC
WATCH: Geomagnetic Storm Category G2 Predicted
Highest Storm Level Predicted by Day:
Mar 17: None (Below G1) Mar 18: None (Below G1) Mar 19: G2 (Moderate)
THIS SUPERSEDES ANY/ALL PRIOR WATCHES IN EFFECT
Comment: G2 (Moderate) geomagnetic storming is likely on 19 Mar with the arrival of a CME that left the Sun on 16 Mar. This is a reissue of the previous watch to correct an internal system error.
NOAA Space Weather Scale descriptions can be found at
www.swpc.noaa.gov/noaa-scales-explanation
Potential Impacts: Area of impact primarily poleward of 55 degrees Geomagnetic Latitude.
Induced Currents - Power grid fluctuations can occur. High-latitude power systems may experience voltage alarms.
Spacecraft - Satellite orientation irregularities may occur; increased drag on low Earth-orbit satellites is possible.
Radio - HF (high frequency) radio propagation can fade at higher latitudes.
Aurora - Aurora may be seen as low as New York to Wisconsin to Washington state.
-------------------
Product ID: A30F
Issued: 2026-03-16 20:25:18.200
Message Follows:
Space Weather Message Code: WATA30
Serial Number: 264
Issue Time: 2026 Mar 16 2025 UTC
WATCH: Geomagnetic Storm Category G2 Predicted
Highest Storm Level Predicted by Day:
Mar 17: None (Below G1) Mar 18: None (Below G1) Mar 19: G2 (Moderate)
THIS SUPERSEDES ANY/ALL PRIOR WATCHES IN EFFECT
Comment: G2 (Moderate) geomagnetic storming is likely on 19 Mar with the arrival of the 16 Mar CME event. This event was associated with an M2.7 flare from AR 4392.
NOAA Space Weather Scale descriptions can be found at
www.swpc.noaa.gov/noaa-scales-explanation
Potential Impacts: Area of impact primarily poleward of 55 degrees Geomagnetic Latitude.
Induced Currents - Power grid fluctuations can occur. High-latitude power systems may experience voltage alarms.
Spacecraft - Satellite orientation irregularities may occur; increased drag on low Earth-orbit satellites is possible.
Radio - HF (high frequency) radio propagation can fade at higher latitudes.
Aurora - Aurora may be seen as low as New York to Wisconsin to Washington state.
-------------------
Product ID: EF3A
Issued: 2026-03-16 13:20:36.937
Message Follows:
Space Weather Message Code: ALTEF3
Serial Number: 3648
Issue Time: 2026 Mar 16 1320 UTC
CONTINUED ALERT: Electron 2MeV Integral Flux exceeded 1000pfu
Continuation of Serial Number: 3647
Begin Time: 2026 Mar 15 1630 UTC
Yesterday Maximum 2MeV Flux: 1429 pfu
Potential Impacts: Satellite systems may experience significant charging resulting in increased risk to satellite systems.
-------------------
Product ID: BHIS
Issued: 2026-03-16 12:29:37.860
Message Follows:
Space Weather Message Code: SUM10R
Serial Number: 901
Issue Time: 2026 Mar 16 1229 UTC
SUMMARY: 10cm Radio Burst
Begin Time: 2026 Mar 16 1209 UTC
Maximum Time: 2026 Mar 16 1213 UTC
End Time: 2026 Mar 16 1217 UTC
Duration: 8 minutes
Peak Flux: 380 sfu
Latest Penticton Noon Flux: 109 sfu
Comment: Associated with M2.7 flare from AR 4392.
Description: A 10cm radio burst indicates that the electromagnetic burst associated with a solar flare at the 10cm wavelength was double or greater than the initial 10cm radio background. This can be indicative of significant radio noise in association with a solar flare. This noise is generally short-lived but can cause interference for sensitive receivers including radar, GPS, and satellite communications.
-------------------
Product ID: TIVA
Issued: 2026-03-16 12:26:18.087
Message Follows:
Space Weather Message Code: ALTTP4
Serial Number: 705
Issue Time: 2026 Mar 16 1226 UTC
ALERT: Type IV Radio Emission
Begin Time: 2026 Mar 16 1212 UTC
Description: Type IV emissions occur in association with major eruptions on the sun and are typically associated with strong coronal mass ejections and solar radiation storms.
Current 2026 Mar 18 1205 UTC
Solar-terrestrial indices for 17 March follow.
Solar flux 111 and estimated planetary A-index 4.
The estimated planetary K-index at 1200 UTC on 18 March was 1.67.
Space weather for the past 24 hours has been minor.
Radio blackouts reaching the R1 level occurred.
Space weather for the next 24 hours is predicted to be moderate.
Geomagnetic storms reaching the G2 level .
Official Space Weather Advisory issued by NOAA Space Weather Prediction Center
Boulder, Colorado, USA
SPACE WEATHER ADVISORY OUTLOOK #26-11
2026 March 15 at 6:24 p.m. MDT (2026 March 16 0024 UTC)
**** SPACE WEATHER OUTLOOK ****
Summary For March 9-15
G1 (Minor) and G2 (Moderate) geomagnetic storms were observed on 13 and 14 March.
R1 (Minor) radio blackouts were observed on 13 and 15 March.
No other significant space weather activity was observed.
Outlook For March 16-22
R1-R2 (Minor-Moderate) radio blackouts are likely on 21 and 22 March.
No other significant space weather activity is expected.