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
No significant space weather is expected initially, with aurora sightings unlikely. Later on Wednesday 23rd September, fast winds are expected to arrive, bringing a chance of aurora sightings on Wednesday 23rd and Thursday 24th September across parts of Scotland, where skies are clear.
Southern Hemisphere
No significant space weather is expected initially, with aurora sightings unlikely. Later on Wednesday 23rd September UTC, fast winds are expected to arrive, bringing a chance of aurora sightings on Wednesday 23rd and Thursday 24th September UTC across southern parts of New Zealand, where skies are clear.
Issued at: 21:08 (GMT) on Mon 21 Sep 2026
Forecast overview
Space Weather Forecast Headline: Generally quiet Space Weather conditions initially, then Chance of G1/Minor Geomagnetic Storming on Days 2 and 3.
Analysis of Space Weather Activity over past 24 hours
Solar Activity:
Solar activity has been Low, peaking with a C1.13 at 21/0113 UTC from AR4534 near centre disk. There are six sunspot regions on the visible disc. AR4534, in the north centre disk, is the most active sunspot region. All regions are currently small and simple.
There were no Earth-directed CMEs observed during the period.
Solar Wind / Geomagnetic Activity: Solar wind speeds, as measured at L1 by SOLAR-1, were at slow background values. The Interplanetary Magnetic Field, Bt, was Weak and fairly steady. The north-south component, Bz, was largely neutral. Geomagnetic activity was Quiet (Kp 0-2).
Energetic Particles / Solar Radiation: GOES18 >10MeV proton flux was at normal background levels.
Four-Day Space Weather Forecast Summary
Solar Activity: Solar activity is forecast to remain Low or Very Low, with a Slight Chance of becoming Moderate.
Solar Wind / Geomagnetic Activity: No Earth-directed Coronal Mass Ejections currently feature in the forecast period. Solar winds are expected to be largely background speeds until later Day 2 (23 Sep). Thereafter, wind speeds should become 500-600km/s from the enhancement of CH96/+, which is currently anticipated to occur either later on Day 2 (23 Sep) or on Day 3 (24 Sep).
Geomagnetic activity is forecast to be mostly Quiet throughout the start of the period, with a slight chance of isolated Unsettled intervals. From later Day 2 (23 Sep) or early Day 3 (24 Sep), due to the onset of coronal hole fast winds, Active (Kp4) intervals are Likely, with a Chance of G1/Minor Storms (Kp5) or G2/Moderate storms.
Energetic Particles / Solar Radiation: GOES18 >10MeV proton flux is expected to remain at background levels.
Issued at: 00:17 (GMT) on Tue 22 Sep 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: