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| Warnings and Alerts | |
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Issue Time: 2025 Dec 20 1236 UTC
WATCH: Geomagnetic Storm Category G1 Predicted Highest Storm Level Predicted by Day: Dec 21: None (Below G1) Dec 22: G1 (Minor) Dec 23: G1 (Minor) THIS SUPERSEDES ANY/ALL PRIOR WATCHES IN EFFECT 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. Space Weather Scales |
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| Current Condition and Alerts | |
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Issued: 2025 Dec 20 1205 UTC
Prepared
by the US Dept. of Commerce, NOAA, Space Weather Prediction
Center
Geophysical Alert Message Solar-terrestrial indices for 19 December follow. Solar flux 118 and estimated planetary A-index 6. The estimated planetary K-index at 1200 UTC on 20 December was 1.33. Space weather for the past 24 hours has been minor. Radio blackouts reaching the R1 level occurred. No space weather storms are predicted for the next 24 hours. Space Weather Scales |
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| Forecast Discussion | |
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Issued: 2025 Dec 20 1230 UTC
Prepared
by the U.S. Dept. of Commerce, NOAA, Space Weather Prediction
Center
Solar Activity .24 hr Summary... Solar activity reached moderate levels this period. Notable activity included an M1.0 flare at 19/1558 UTC from a region beyond the southwest limb, and an M1.1/Sf flare at 20/0753 UTC from new Region 4315 (N20E56, Bxo/beta). New Region 4314 (N23E40, Bxo/beta) was also numbered, but was quiet and otherwise unremarkable. The remaining active regions were either stable or showing signs of decay. No Earth-directed CMEs were observed in available coronagraph imagery. .Forecast... Solar activity is likely to be at low levels with a slight chance for M-class flares over 20-22 Dec. Energetic Particle .24 hr Summary... The greater than 2 MeV electron flux reached high levels with a peak flux of 3,240 pfu observed. The greater than 10 MeV proton flux was steady at background levels. .Forecast... The greater than 2 MeV electron flux is expected to reach high levels on 20-21 Dec, before decreasing to normal to moderate levels on 22 Dec. The greater than 10 MeV proton flux is expected to persist at background levels through 22 Dec. Solar Wind .24 hr Summary... The solar wind environment reflected waning negative polarity CH HSS influences. Total field strength ranged between 1-5 nT, while the Bz component varied between +/-4 nT. Solar wind speeds steadily declined throughout the period from a peak near 550 km/s to around 475 km/s. Phi transitioned from negative to positive at around 20/0110 UTC. .Forecast... Ambient solar wind conditions are expected to prevail over 20-21 Dec. On 22 Dec, enhanced solar wind conditions are likely due to the anticipated onset of CIR effects followed by positive polarity CH HSS influences. Geospace .24 hr Summary... The geomagnetic field was quiet throughout the period. .Forecast... The geomagnetic field is expected to be mostly quiet over 20-21 Dec. Active conditions and periods of G1 (Minor) geomagnetic storming are likely on 22 Dec due to the anticipated onset of CIR effects followed by positive polarity CH HSS influences. Space Weather Scales |
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| Three Day Forecast | |
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Issued: 2025 Dec 20 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 2 (below NOAA Scale levels). The greatest expected 3 hr Kp for Dec 20-Dec 22 2025 is 4.67 (NOAA Scale G1). NOAA Kp index breakdown Dec 20-Dec 22 2025 Dec 20 Dec 21 Dec 22 00-03UT 2.00 1.67 1.67 03-06UT 0.67 1.67 2.00 06-09UT 1.33 1.67 1.67 09-12UT 1.33 1.33 3.00 12-15UT 0.67 0.67 3.67 15-18UT 0.67 1.33 3.67 18-21UT 1.67 0.67 4.00 21-00UT 1.67 1.67 4.67 (G1) Rationale: G1 (Minor) geomagnetic storming is likely on 22 Dec due to the anticipated onset of CIR effects followed by positive polarity CH HSS influences. 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 20-Dec 22 2025 Dec 20 Dec 21 Dec 22 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 Radio blackouts reaching the R1 levels were observed over the past 24 hours. The largest was at Dec 19 2025 1558 UTC. Radio Blackout Forecast for Dec 20-Dec 22 2025 Dec 20 Dec 21 Dec 22 R1-R2 10% 10% 10% R3 or greater 1% 1% 1% Rationale: There is a slight chance for R1-R2 (Minor-Moderate) radio blackouts on 20-22 Dec. Space Weather Scales |
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| Weekly Highlights and Forecasts | |
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Issued: 2025 Dec 15 0446 UTC
Prepared
by the US Dept. of Commerce, NOAA, Space Weather Prediction
Center
Highlights of Solar and Geomagnetic Activity 08 - 14 December 2025 Solar activity reached high levels this week, with a single X-flare and multiple (16) M-flares. Region 4298 (S16, L=305, class/area Cso/60 on 10 Dec) produced the only X-flare of the period: an X1.1/2b flare at 08/0501 UTC. Other notable activity included multiple M-class flares from several different regions. Region 4294 (S15, L=284, class/area Ekc/1180 on 08 Dec) was responsible for the majority of the M-flares, including: an M2.2/1n at 08/0036 UTC, an M1.0/Sf at 08/1305 UTC, an M3.1/Sf at 08/2117 UTC, an M1.1 at 09/0138 UTC, an M1.0/Sf at 09/0729 UTC, an M1.3/Sf at 090739 UTC, an M1.6/Sf at 09/0747 UTC, an M1.5/Sf at 091514 UTC, an M1.2/Sf at 10/0422 UTC, an M1.9/Sf at 10/0737 UTC, an M1.0/1f at 10/0955 UTC, an M1.6/Sf at 10/1343 UTC, an M4.4/2b at 10/2208 UTC, and an M1.1 at 12/0544 UTC. Region 4296 (S14, L=272, class/area Ekc/500 on 08 Dec) contributed two M-flares: an M1.5/Sf at 09/2327 UTC, and an M2.0 at 12/0505 UTC. Region 4299 (N22, L=267, class/area Dai/130 on 08 Dec) added three M-flares: an M2.4/2n at 08/0012 UTC, an M1.2/Sn at 08/2228 UTC, and an M2.0 at 09/0058 UTC. Finally, Region 4304 (N26, L=252, class/area Cai/110 on 11 Dec) produced a single M-flare: an M1.8/1n at 08/0654 UTC. Multiple radio events accompanied some of the flares, with a total of eight Type II and three Type IV radio sweeps, as well as a 10cm radio burst. These included: a Type II (est 317 km/s) associated with the M2.4/2n at 08/0012 UTC, a Type II (est 347 km/s) associated with the X1.1/2b at 08/0036 UTC, a Type II (est 1825 km/s) and Type IV associated with the M1.1 at 09/0138 UTC, a Type II (est 759 km/s) thought to be associated with a far sided flare event, a Type II (est 1053 km/s) associated with the M1.6/Sf at 10/1343 UTC, a Type II (est 849 km/s) and 10cm burst (168 sfu) associated with the M4.4/2b at 10/2208 UTC, a Type II (est 410 km/s) and Type IV associated with the M2.0 at 12/0505 UTC, and a Type IV associated with the M1.1 at 12/0544 UTC. Several CMEs were analyzed throughout the period, with only a couple thought to have an Earth-directed component. The most notable event was from the X1.1/2b flare that had a westerly trajectory with an analyzed glancing arrival at Earth late on 10 Dec to early on 11 Dec. There is a possibility this CME contributed to the G2 (Mod) geomagnetic storming event on 10-11 Dec. There was also a CME from the M4.4/2b flare from Region 4294 at 10/2208 UTC, but the resulting analysis indicated the bulk of the ejecta would pass ahead of Earth. However, it is possible more of the ejecta could have passed near enough to Earth on 13 Dec, combined with CH HSS effects, and enhanced conditions to the G1 (Minor) storm levels. The majority of the other CMEs were deemed to not have Earth-directed components. The greater than 10 MeV proton flux was at background levels throughout the period. The greater than 2 MeV electron flux at geosynchronous orbit was at high levels on 08-09 Dec, and at normal to moderate levels on 10-14 Dec. Geomagnetic field activity was at quiet to unsettled levels on 08, 09, and most of 10 Dec, as well as 14 Dec. G2 (Moderate) storm levels were observed the last period of 10 Dec and the first synoptic period on 11 Dec following the arrival of a CME that likely left the Sun on 08 Dec. Active to G1 (Minor) storming was observed on 12 and 13 Dec in response to negative polarity CH HSS influence mixed with possible transient effects. Forecast of Solar and Geomagnetic Activity 15 December - 10 January 2026 M-class flares (R1-R2/Minor-Moderate) are likely, with a chance for X-class (R3/Strong) flares through the outlook period. Chances could increase if new, more magnetically complex regions develop or return during the period. Barring significant development of new active regions, the greater than 10 MeV proton flux is expected to remain below the 10 pfu (S1-Minor) levels throughout the outlook period. The greater than 2 MeV electron flux is expected to reach high levels on 16-19 Dec, 25-29 Dec, and 01-06 Jan. Normal to moderate levels expected to prevail on 15, 20-24, 30-31 Dec, and 07-10 Jan. Geomagnetic field activity is likely to reach G1 (Minor) storm levels on 18 Dec, 30-31 Dec, and possibly 09 Jan, due to negative polarity CH HSS influences. G1 levels are also likely on 22-26 Dec, due to positive polarity CH HSS influences. Unsettled to active levels are likely on 15-17, 19-20 Dec, 01-03 Jan, and 08-10 Jan under the influence of negative polarity CH HSS, and on 27-29 Dec under positive polarity CH HSS influence. Mostly quiet conditions are expected on 21 Dec and 04-08 Jan. Space Weather Scales |
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| About AIA Images | |
| The Atmospheric Imaging Assembly (AIA) on the Solar Dynamics Observatory (SDO) is designed to provide an unprecedented view of the solar corona, taking images that span at least 1.3 solar diameters in multiple wavelengths nearly simultaneously, at a resolution of ~ 1 arcsec and at a cadence of 10 s or better. The primary goal of the AIA Science Investigation is to use these data, together with data from other SDO instruments and from other observatories, to significantly improve our understanding of the physics behind the activity displayed by the Sun's atmosphere, which drives space weather in the heliosphere and in planetary environments. The AIA will produce data required for quantitative studies of the evolving coronal magnetic field, and the plasma that it holds, both in quiescent phases and during flares and eruptions; the AIA science investigation aims to utilize these data in a comprehensive research program to provide new understanding of the observed processes Left Click Image for screen size, Right Click Image and open in new tab for full size. | |
| Daily Image AIA 171 | |
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| Daily Image AIA 171 PFSS Model | |
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| Daily Image AIA 193 | |
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| Daily Image AIA 304 | |
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| Daily Video AIA 171 | |
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| Daily Video AIA 171 PFSS Model | |
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| Daily Video AIA 193 | |
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| Daily Video AIA 304 | |
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| About the HMI Images | |
| (Helioseismic and Magnetic Imager) HMI is an instrument designed to study oscillations and the magnetic field at the solar surface, or photosphere. HMI is one of three instruments on the Solar Dynamics Observatory; together, the suite of instruments observes the Sun nearly continuously and takes a terabyte of data a day. HMI observes the full solar disk at 6173 Å with a resolution of 1 arcsecond. HMI is a successor to the Michelson Doppler Imager on the Solar and Heliospheric Observatory. This is very much how the Sun looks like in the visible range of the spectrum (for example, looking at it using special 'eclipse' glasses: Remember, do not ever look directly at the Sun!). The magnetogram image shows the magnetic field in the solar photosphere, with black and white indicating opposite polarities. Left Click Image for screen size, Right Click Image and open in new tab for full size. | |
| Daily Image HMI Continuum | |
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| Daily Image HMI Magnetogram | |
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| About LASCO Images | |
| LASCO (Large Angle Spectrometric Coronagraph) is able to take images of the solar corona by blocking the light coming directly from the Sun with an occulter disk, creating an artificial eclipse within the instrument itself. The position of the solar disk is indicated in the images by the white circle. The most prominent feature of the corona are usually the coronal streamers, those nearly radial bands that can be seen both in C2 and C3. Occasionally, a coronal mass ejection can be seen being expelled away from the Sun and crossing the fields of view of both coronagraphs. The shadow crossing from the lower left corner to the center of the image is the support for the occulter disk. C2 images show the inner solar corona up to 8.4 million kilometers (5.25 million miles) away from the Sun. C3 images have a larger field of view: They encompass 32 diameters of the Sun. To put this in perspective, the diameter of the images is 45 million kilometers (about 30 million miles) at the distance of the Sun, or half of the diameter of the orbit of Mercury. Many bright stars can be seen behind the Sun. Left Click Image for screen size, Right Click Image and open in new tab for full size. | |
| Combined C2 C3 and AIA 304 | |
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| Log Polar View C2 C3 and AIA 304 | |
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| Combined C2 C3 and AIA 304 Video | |
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| Log Polar View C2 C3 and AIA 304 Video | |
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| Space Weather Videos | |
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| Space Weather Information | |
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Demystifying Space Weather An article by Scientific Frontline Informative information and glossary about “Space Weather” Space weather has become increasingly important in our modern world due to our growing reliance on technology. It can impact various aspects of our daily lives, from communication and navigation systems to power grids and even astronaut safety. In this deep dive, we'll explore the intricacies of space weather, its causes, its effects, and why understanding it is crucial in our technology-dependent society. |
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