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.
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Aurora forecasts
Northern Hemisphere
Mostly background aurora is expected, although ongoing fast winds could bring some occasional slight enhancements. There is a low chance for some brief visibility across the far north of Scotland through Friday night (UTC), where skies are clear.
Southern Hemisphere
Mostly background aurora is expected, although ongoing fast winds, could bring some occasional slight enhancements. There is a low chance for some brief visibility from the south coast of New Zealand on Friday night (UTC) where skies are clear.
Issued at: 01:57 (GMT) on Fri 21 Aug 2026
Forecast overview
Space Weather Forecast Headline: Chance of Moderate-class flares throughout.
Analysis of Space Weather Activity over past 24 hours
Solar Activity: Moderate with three peak Moderate-class flares from a new sunspot region rotating around the northeast limb.
There are currently four numbered sunspot regions on the visible disc, of which the region near the northeast limb is by far the most significant as it is the largest region, appears to be growing, and appears to be magnetically complex. The remaining regions are smaller, mostly magnetically simple, weaker and stable.
No Earth directed CMEs are currently expected. The CME associated with the largest Moderate class flare has now analysed and is expected to miss Earth.
Solar Wind / Geomagnetic Activity: Solar winds as measured by L1 at SOLAR-1, were indicative of a fast wind regime, from two coronal holes, with speeds generally Elevated, peaking at 598km/s at 20/0404 UTC. Interplanetary Magnetic Field, Bt, has been Weak. The north-south component, Bz, has been Weak. Geomagnetic activity was Quiet to Unsettled.
Energetic Particles / Solar Radiation: GOES18 >10MeV proton flux was at Background.
Four-Day Space Weather Forecast Summary
Solar Activity: Activity is likely to be Low to Moderate, with a chance of further Moderate-class flares and a slight chance of a Strong flare, mostly from the region near the northeast limb. A new or returning region is expected to rotate onto the disc, from the far side, most likely during Day 3 (23 Aug). However, this region is not expected to significantly influence solar activity.
Solar Wind / Geomagnetic Activity: A Coronal Mass Ejection (CME) associated with a Common-class flare from 16 August is now considered to have missed Earth. Earth is currently under the influence of a solar wind enhancement from one or two coronal holes in the western hemisphere. The solar wind enhancement is expected to gradually decline through the period, from initial Elevated speeds around 500 km/s down to Background levels during Days 3 and 4 (23 and 24 Aug). Geomagnetic activity is expected to remain Quiet to Unsettled overall, with a chance for periods of Active (Kp 4), mainly on Day 1 (21 Aug).
Energetic Particles / Solar Radiation: GOES-18 > MeV proton flux is at background with only a slight chance of rising given any eruptive events from the disc.
Issued at: 00:27 (GMT) on Fri 21 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.
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