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| Warnings and Alerts | |
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Issue Time: 2026 Apr 18 0752 UTC
WARNING: Geomagnetic K-Index of 6 expected Valid From: 2026 Apr 18 0751 UTC Valid To: 2026 Apr 18 1500 UTC Warning Condition: Onset NOAA Scale: G2 - Moderate 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. Space Weather Scales |
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| Current Condition and Alerts | |
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Issued: 2026 Apr 18 1205 UTC
Prepared
by the US Dept. of Commerce, NOAA, Space Weather Prediction
Center
Geophysical Alert Message Solar-terrestrial indices for 17 April follow. Solar flux 107 and estimated planetary A-index 4. The estimated planetary K-index at 1200 UTC on 18 April was 5.00. Space weather for the past 24 hours has been moderate. Geomagnetic storms reaching the G2 level occurred. Space weather for the next 24 hours is predicted to be moderate. Geomagnetic storms reaching the G2 level are expected. Space Weather Scales |
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| Forecast Discussion | |
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Issued: 2026 Apr 18 1230 UTC
Prepared
by the U.S. Dept. of Commerce, NOAA, Space Weather Prediction
Center
Solar Activity .24 hr Summary... Solar activity was at low levels. Region 4416 (N22W85, Cso/beta) produced the largest event of the period, a C1.6 flare at 18/0704 UTC, as it rotated around the western limb. Region 4419 (N13E8, Eki/beta-gamma) displayed slight decay and consolidation in its trailing spots, with the leader spots separating yet decaying as well. Region 4415 (S18W68, Hsx/alpha) remained unchanged and was unremarkable. From around 18/0730-0823 UTC, an approximately 30 degree long eruptive filament was observed in GONG H-alpha and GOES-19 SUVI imagery lifting off the solar disk. The associated CME will be modeled when coronagraph imagery becomes available. No other Earth directed CMEs were observed in coronagraph imagery. .Forecast... Solar activity is expected to be low with a chance for M-class (R1-R2, Minor-Moderate) flares on 18-20 Apr, primarily due to the flare potential of Region 4419. Energetic Particle .24 hr Summary... The greater than 2 MeV electron flux at geosynchronous orbit reached high levels with a peak of 2,441 pfu observed at 17/1650 UTC. The greater than 10 MeV proton flux was at background levels. .Forecast... The greater than 2 MeV electron flux is expected to briefly drop to normal to moderate levels on 18 Apr with the arrival of a negative polarity CH HSS. Flux levels are expected to increase back to high levels on 19-20 Apr. The greater than 10 MeV proton flux is expected to continue at background levels on 18-20 Apr. Solar Wind .24 hr Summary... Solar wind parameters were at nominal levels the first half of the reporting period. At around 17/2300 UTC, enhancements were noted as the anticipated CH HSS moved into a geoeffective position. Total field increased to a peak of 17 nT, while the Bz component was mostly negative, seeing a maximum southward deflection to -14 nT. Solar wind speeds varied between approximately 280-360 km/s before gradually increasing to a maximum velocity of ~540 km/s. Phi rotated into a negative orientation just after 18/2300 UTC. .Forecast... Solar wind parameters are expected to remain enhanced on 18 Apr as negative polarity CH HSS influence persists. Solar wind speeds ranging from 600-700 km/s are likely based on recurrent values. Enhanced conditions are expected to continue through 20 Apr. Geospace .24 hr Summary... The geomagnetic field reached G1 (Minor) levels before increasing to G2 (Moderate) levels after 18/0825 UTC. .Forecast... G1-G2 (Minor-Moderate) geomagnetic storming levels are expected on 18 Apr as negative polarity CH HSS geomagnetic conditions persist. Active to G1 (Minor) levels are expected to continue through 19 Apr, followed by unsettled to active conditions on 20 Apr, as HSS effects linger. Space Weather Scales |
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| Three Day Forecast | |
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Issued: 2026 Apr 18 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 6 (NOAA Scale G2). The greatest expected 3 hr Kp for Apr 18-Apr 20 2026 is 6.00 (NOAA Scale G2). NOAA Kp index breakdown Apr 18-Apr 20 2026 Apr 18 Apr 19 Apr 20 00-03UT 3.33 5.00 (G1) 3.67 03-06UT 5.00 (G1) 4.67 (G1) 3.67 06-09UT 5.67 (G2) 4.00 3.33 09-12UT 5.00 (G1) 3.33 3.33 12-15UT 5.00 (G1) 3.67 3.33 15-18UT 4.33 3.00 2.00 18-21UT 4.00 3.00 3.33 21-00UT 6.00 (G2) 3.33 3.33 Rationale: G1-G2 (Minor-Moderate) geomagnetic storming levels are expected on 18 Apr as negative polarity CH HSS geomagnetic conditions persist. Active to G1 (Minor) levels are expected to continue through 19 Apr, followed by unsettled to active conditions on 20 Apr, as HSS effects linger. 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 Apr 18-Apr 20 2026 Apr 18 Apr 19 Apr 20 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 Apr 18-Apr 20 2026 Apr 18 Apr 19 Apr 20 R1-R2 25% 25% 25% R3 or greater 5% 5% 5% Rationale: There is a chance for R1-R2 (Minor-Moderate) flares on 18-20 Apr, primarily due to the flare potential of Region 4419.#sued: 2026 Apr 18 1230 UTC Space Weather Scales |
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| Weekly Highlights and Forecasts | |
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Issued: 2026 Apr 13 0104 UTC
Prepared
by the US Dept. of Commerce, NOAA, Space Weather Prediction
Center
Highlights of Solar and Geomagnetic Activity 06 - 12 April 2026 Solar activity was at very low to moderate levels during the period. Moderate levels were reached on 09 Apr, with low levels observed on 06-08 Apr and 11-12 Apr. Very low levels occurred on 10 Apr. Region 4409 (N02, L=158, class/area=Eai/190 on 07 Apr) was the most active region of the period, producing 11 C-class flares and the only M-class flare of the period, an impulsive M1.0/Sf at 09/0845 UTC. Region 4417 (S08, L=123, class/area=Dao/30 on 12 Apr) also contributed notable activity with 7 C-class flares after appearing quickly on 11 Apr near the West limb. Other activity included a C8.7/Sf flare from Region 4414 (N15, L=26, class/area Dro/30 on 08 Apr) at 08/1543 UTC, which was associated with Type III radio emissions and a weak CME without any Earth-directed components. No proton events were observed at geosynchronous orbit. The greater than 2 MeV electron flux at geosynchronous orbit was at high levels throughout the reporting period. Flux levels reached a peak value of 10,679 pfu at 09/1605 UTC. Geomagnetic field activity ranged from quiet to active levels during the period. The beginning of the period (06-07 Apr) saw quiet to unsettled conditions as the influence of a negative polarity coronal hole high speed stream (-CH HSS) continued to wane. From 10-12 Apr, quiet to active levels were observerd under the onset and influence of a positive polarity CH HSS (+CH HSS). Quiet conditions prevailed during all other days of the period under a nominal solar wind regime. Forecast of Solar and Geomagnetic Activity 13 April - 09 May 2026 Solar activity is expected to be at low levels, with a varying chance for M-class (R1-R2/Minor-Moderate) flares and a slight chance for X-class (R3/Strong or greater) flares through 09 May. No proton events are expected at geosynchronous orbit, barring any significant, non-recurrent solar activity. The greater than 2 MeV electron flux at geosynchronous orbit is expected to reach high levels on 13-17 Apr, 19-24 Apr, 26-28 Apr, 30 Apr-05 May, and 08-09 May. Normal to moderate flux levels are expected on 18 Apr, 25 Apr, 29 Apr, and 06-07 May. Geomagnetic field activity is anticipated to reach G1-G2 (Minor-Moderate) storm levels on 19 Apr and 29 Apr due to -CH HSS influences, and on 07 May due to +CH HSS influences. Active conditions are expected on 18 Apr, 20 Apr, and 30 Apr-01 May in response to -CH HSS effects, and on 15 Apr, 25 Apr, and 08 May due to +CH HSS effects. Mostly quiet to unsettled conditions are expected for all other days of the period. 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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| Daily Video HMI Continuum | |
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| Daily Video 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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