| TYPE | RADIO BLACKOUT | SOLAR STORM | GEO STORM |
|---|---|---|---|
| SCALE | 1-2: 1%, 3-5: 15% | 1% | 0 |
| TEXT | None | S1 or < | none |
| 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: 1%, 3-5: 1% | 1% | 0 |
| TEXT | None | S1 or < | none |
:Product: 3-Day Forecast
:Issued: 2025 Dec 16 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 3 (below NOAA
Scale levels).
The greatest expected 3 hr Kp for Dec 16-Dec 18 2025 is 5.00 (NOAA Scale
G1).
NOAA Kp index breakdown Dec 16-Dec 18 2025
Dec 16 Dec 17 Dec 18
00-03UT 3.33 1.67 5.00 (G1)
03-06UT 2.67 2.00 4.67 (G1)
06-09UT 2.00 2.00 4.00
09-12UT 2.00 2.00 3.67
12-15UT 2.00 3.00 3.00
15-18UT 1.33 3.33 3.00
18-21UT 0.67 4.00 2.67
21-00UT 1.67 4.33 3.33
Rationale: G1 (Minor) or greater geomagnetic storms are expected on Dec
18 due to the passage of a coronal hole high speed stream.
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 Dec 16-Dec 18 2025
Dec 16 Dec 17 Dec 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.
C. NOAA Radio Blackout Activity and Forecast
No radio blackouts were observed over the past 24 hours.
Radio Blackout Forecast for Dec 16-Dec 18 2025
Dec 16 Dec 17 Dec 18
R1-R2 20% 20% 20%
R3 or greater 1% 1% 1%
Rationale: There is a slight chance for R1-R2 (Minor-Moderate) radio
blackouts through 18 Dec.
Updated last 2025/12/17 03:15 UTC
-------------------
Product ID: A20F
Issued: 2025-12-17 00:04:00.393
Message Follows:
Space Weather Message Code: WATA20
Serial Number: 1082
Issue Time: 2025 Dec 17 0004 UTC
CANCEL WATCH: Geomagnetic Storm Category G1 Predicted
Cancel Serial Number: 1081
Original Issue Time: 2025 Dec 15 2245 UTC
Comment: Conditions no longer warrant watch.
NOAA Space Weather Scale descriptions can be found at
www.swpc.noaa.gov/noaa-scales-explanation
Potential Impacts: Area of impact primarily poleward of 60 degrees Geomagnetic Latitude.
Induced Currents - Weak power grid fluctuations can occur.
Spacecraft - Minor impact on satellite operations possible.
Aurora - Aurora may be visible at high latitudes, i.e., northern tier of the U.S. such as northern Michigan and Maine.
-------------------
Product ID: K04W
Issued: 2025-12-16 01:11:20.320
Message Follows:
Space Weather Message Code: WARK04
Serial Number: 5185
Issue Time: 2025 Dec 16 0111 UTC
WARNING: Geomagnetic K-index of 4 expected
Valid From: 2025 Dec 16 0110 UTC
Valid To: 2025 Dec 16 0600 UTC
Warning Condition: Onset
NOAA Space Weather Scale descriptions can be found at
www.swpc.noaa.gov/noaa-scales-explanation
Potential Impacts: Area of impact primarily poleward of 65 degrees Geomagnetic Latitude.
Induced Currents - Weak power grid fluctuations can occur.
Aurora - Aurora may be visible at high latitudes such as Canada and Alaska.
-------------------
Product ID: A20F
Issued: 2025-12-15 22:45:15.507
Message Follows:
Space Weather Message Code: WATA20
Serial Number: 1081
Issue Time: 2025 Dec 15 2245 UTC
WATCH: Geomagnetic Storm Category G1 Predicted
Highest Storm Level Predicted by Day:
Dec 16: None (Below G1) Dec 17: None (Below G1) Dec 18: G1 (Minor)
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 60 degrees Geomagnetic Latitude.
Induced Currents - Weak power grid fluctuations can occur.
Spacecraft - Minor impact on satellite operations possible.
Aurora - Aurora may be visible at high latitudes, i.e., northern tier of the U.S. such as northern Michigan and Maine.
-------------------
Product ID: TIIA
Issued: 2025-12-14 09:32:09.420
Message Follows:
Space Weather Message Code: ALTTP2
Serial Number: 1458
Issue Time: 2025 Dec 14 0932 UTC
ALERT: Type II Radio Emission
Begin Time: 2025 Dec 14 0744 UTC
Estimated Velocity: 585 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: K04W
Issued: 2025-12-13 14:56:12.210
Message Follows:
Space Weather Message Code: WARK04
Serial Number: 5184
Issue Time: 2025 Dec 13 1456 UTC
EXTENDED WARNING: Geomagnetic K-index of 4 expected
Extension to Serial Number: 5183
Valid From: 2025 Dec 10 2040 UTC
Now Valid Until: 2025 Dec 14 0600 UTC
Warning Condition: Persistence
NOAA Space Weather Scale descriptions can be found at
www.swpc.noaa.gov/noaa-scales-explanation
Potential Impacts: Area of impact primarily poleward of 65 degrees Geomagnetic Latitude.
Induced Currents - Weak power grid fluctuations can occur.
Aurora - Aurora may be visible at high latitudes such as Canada and Alaska.
-------------------
Product ID: TIIA
Issued: 2025-12-13 11:06:54.183
Message Follows:
Space Weather Message Code: ALTTP2
Serial Number: 1457
Issue Time: 2025 Dec 13 1106 UTC
ALERT: Type II Radio Emission
Begin Time: 2025 Dec 13 1049 UTC
Estimated Velocity: 778 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: K05A
Issued: 2025-12-13 03:02:17.843
Message Follows:
Space Weather Message Code: ALTK05
Serial Number: 1930
Issue Time: 2025 Dec 13 0302 UTC
ALERT: Geomagnetic K-index of 5
Threshold Reached: 2025 Dec 13 0259 UTC
Synoptic Period: 0000-0300 UTC
Active Warning: Yes
NOAA Scale: G1 - Minor
NOAA Space Weather Scale descriptions can be found at
www.swpc.noaa.gov/noaa-scales-explanation
Potential Impacts: Area of impact primarily poleward of 60 degrees Geomagnetic Latitude.
Induced Currents - Weak power grid fluctuations can occur.
Spacecraft - Minor impact on satellite operations possible.
Aurora - Aurora may be visible at high latitudes, i.e., northern tier of the U.S. such as northern Michigan and Maine.
-------------------
Product ID: K05A
Issued: 2025-12-12 22:50:46.707
Message Follows:
Space Weather Message Code: ALTK05
Serial Number: 1929
Issue Time: 2025 Dec 12 2250 UTC
ALERT: Geomagnetic K-index of 5
Threshold Reached: 2025 Dec 12 2248 UTC
Synoptic Period: 2100-2400 UTC
Active Warning: Yes
NOAA Scale: G1 - Minor
NOAA Space Weather Scale descriptions can be found at
www.swpc.noaa.gov/noaa-scales-explanation
Potential Impacts: Area of impact primarily poleward of 60 degrees Geomagnetic Latitude.
Induced Currents - Weak power grid fluctuations can occur.
Spacecraft - Minor impact on satellite operations possible.
Aurora - Aurora may be visible at high latitudes, i.e., northern tier of the U.S. such as northern Michigan and Maine.
-------------------
Product ID: K04W
Issued: 2025-12-12 22:37:40.237
Message Follows:
Space Weather Message Code: WARK04
Serial Number: 5183
Issue Time: 2025 Dec 12 2237 UTC
EXTENDED WARNING: Geomagnetic K-index of 4 expected
Extension to Serial Number: 5182
Valid From: 2025 Dec 10 2040 UTC
Now Valid Until: 2025 Dec 13 1500 UTC
Warning Condition: Persistence
NOAA Space Weather Scale descriptions can be found at
www.swpc.noaa.gov/noaa-scales-explanation
Potential Impacts: Area of impact primarily poleward of 65 degrees Geomagnetic Latitude.
Induced Currents - Weak power grid fluctuations can occur.
Aurora - Aurora may be visible at high latitudes such as Canada and Alaska.
-------------------
Product ID: K05A
Issued: 2025-12-12 19:43:20.580
Message Follows:
Space Weather Message Code: ALTK05
Serial Number: 1928
Issue Time: 2025 Dec 12 1943 UTC
ALERT: Geomagnetic K-index of 5
Threshold Reached: 2025 Dec 12 1942 UTC
Synoptic Period: 1800-2100 UTC
Active Warning: Yes
NOAA Scale: G1 - Minor
NOAA Space Weather Scale descriptions can be found at
www.swpc.noaa.gov/noaa-scales-explanation
Potential Impacts: Area of impact primarily poleward of 60 degrees Geomagnetic Latitude.
Induced Currents - Weak power grid fluctuations can occur.
Spacecraft - Minor impact on satellite operations possible.
Aurora - Aurora may be visible at high latitudes, i.e., northern tier of the U.S. such as northern Michigan and Maine.
-------------------
Product ID: K05W
Issued: 2025-12-12 19:42:19.980
Message Follows:
Space Weather Message Code: WARK05
Serial Number: 2155
Issue Time: 2025 Dec 12 1942 UTC
WARNING: Geomagnetic K-index of 5 expected
Valid From: 2025 Dec 12 1940 UTC
Valid To: 2025 Dec 13 0900 UTC
Warning Condition: Onset
NOAA Scale: G1 - Minor
NOAA Space Weather Scale descriptions can be found at
www.swpc.noaa.gov/noaa-scales-explanation
Potential Impacts: Area of impact primarily poleward of 60 degrees Geomagnetic Latitude.
Induced Currents - Weak power grid fluctuations can occur.
Spacecraft - Minor impact on satellite operations possible.
Aurora - Aurora may be visible at high latitudes, i.e., northern tier of the U.S. such as northern Michigan and Maine.
Current 2025 Dec 16 1205 UTC
Solar-terrestrial indices for 15 December follow.
Solar flux 118 and estimated planetary A-index 6.
The estimated planetary K-index at 1200 UTC on 16 December was 2.00.
No space weather storms were observed for the past 24 hours.
No space weather storms are predicted for the next 24 hours.
Official Space Weather Advisory issued by NOAA Space Weather Prediction Center
Boulder, Colorado, USA
SPACE WEATHER ADVISORY OUTLOOK #25-46
2025 December 14 at 10:04 p.m. MST (2025 December 15 0504 UTC)
**** SPACE WEATHER OUTLOOK ****
Summary For December 8-14
- Periods of G2 (Moderate) storming were observed on 10-11 Dec.
- G1 (Minor) storms were observed on 11,12 and 13 Dec.
- An R3 (Strong) event was observed on 08 Dec.
- R1 (Minor) events were observed on 09-12 Dec.
Outlook For December 15-21
- G1 (Minor) storms are likely on 18 Dec.
- There is a chance for R1/R2 (Minor-Moderate) events on 15-21 Dec.