| No. | Type | Alerts | Warnings | Watches |
|---|---|---|---|---|
| 1 | Kp Alert |
G1:
18:00 (GMT) on Tue 18 Aug 2026 to 21:00 (GMT) on Tue 18 Aug 2026 |
Space Weather
Space weather describes changing environmental conditions in near-Earth space. Magnetic fields, radiation, particles and matter, which have been ejected from the Sun, can interact with the Earth’s upper atmosphere and surrounding magnetic field to produce a variety of effects.
Space weather notifications
Aurora forecasts
Northern Hemisphere
Fast winds may cause an enhancement to the auroral oval across northern Scotland and similar latitudes on Tuesday night, although cloud cover likely limiting sightings. Ongoing fast winds along with a potential low confidence glancing coronal mass ejection impact on Thursday may cause aurora to become visible again across Northern Scotland and similar latitudes Wednesday and Thursday night, before aurora returns to background levels on Friday.
Southern Hemisphere
Fast winds may cause an enhancement to the auroral oval across the far south of New Zealand and similar latitudes on Tuesday UTC night. Ongoing fast winds along with a potential low confidence glancing CME on Thursday may cause aurora to become visible again across far south of New Zealand and similar latitudes Wednesday and Thursday, before aurora returns to background levels on Friday.
Issued at: 13:44 (GMT) on Tue 18 Aug 2026
Forecast overview
Space Weather Forecast Headline: Chance of G1/Minor storms Days 2-3 (19-20 Aug). Chance of Moderate class flares.
Chance of Moderate class flares.
Analysis of Space Weather Activity over past 24 hours
Solar Activity: Solar activity has been Low, with only low-level Common-class flares observed in the past 24 hours.
There are currently four sunspot regions on the Earth-facing disc. The most complex region is in the western, central part of the disc. It has seen some growth in it's intermediate spots over the last few hours along with developing some spots of mixed-polarity. The two smaller spots in the northwest have also seen some minor growth in recent hours. The one remaining spot is smaller and more simple.
No Earth directed CMEs were observed during this period.
Solar Wind / Geomagnetic Activity: Solar winds showed some slightly perturbed conditions. This could be due to a very glancing blow from the expected Coronal Mass Ejection (CME) in association with a filament (arc of plasma) eruption on 14 Aug, or from a co-rotating interaction region (CIR) ahead of the next fast wind from two of the coronal holes facing Earth, but this is low confidence. Solar wind speeds were initially at background, around 300km/s, before increasing to reach Slightly Elevated levels, peaking at 430km/s. The Interplanetary Magnetic Field, Bt, was Moderate. The north-south component, Bz, was moderately variable, but favoured a negative direction to end this period. Geomagnetic activity was Quiet to Active (Kp2-4).
Energetic Particles / Solar Radiation: GOES18 >10MeV proton flux was at background levels.
Four-Day Space Weather Forecast Summary
Solar Activity: Activity will most likely remain Low, however there is a chance of isolated Moderate-class flares, most likely from AR4507.
Solar Wind / Geomagnetic Activity:
A Coronal mass Ejection (CME) associated with a Common-class flare from the largest region in the western hemisphere on the 16 Aug may deliver a glancing blow at Earth on Day 3 (20 Aug). Confidence is low.
A fast wind from a couple of coronal holes which are facing Earth may arrive during this period, perhaps late on Day 1 (18 Aug), but more likely through Day 2 (19 Aug), before gradually declining through Days 3-4 (20-21 Aug). Solar wind speeds reached 700 km/s on last rotation, but there is significant uncertainty regarding possible speeds this time around.
Geomagnetic activity is expected to be Quiet to Active (Kp1-4) on Day 1 (18 Aug) due to waning CME or CIR influences. The next enhancement will be the fast wind from the two coronal holes facing Earth, either late Day 1 (18 Aug), or more likely through Day 2 (19 Aug), which along with glancing CME effects on Day 3 (20 Aug) keeps a chance of G1/Minor Storms through Days 2 and 3 (19-20 Aug), before activity likely returns to mostly Quiet to Unsettled levels on Day 4 (21 Aug).
Energetic Particles / Solar Radiation: GOES18 >10MeV proton flux is likely to continue at background levels.
Issued at: 12:03 (GMT) on Tue 18 Aug 2026
Solar imagery
SDO AIA-193
This channel highlights the outer atmosphere of the Sun - called the corona - as well as hot flare plasma. Hot active regions, solar flares, and coronal mass ejections will appear bright here. The dark areas - called coronal holes - are places where very little radiation is emitted, yet are the main source of solar wind particles.
Issued at:
SDO AIA-304
This channel is especially good at showing areas where cooler dense plumes of plasma (filaments and prominences) are located above the visible surface of the Sun. Many of these features either can't be seen or appear as dark lines in the other channels. The bright areas show places where the plasma has a high density.
Issued at: