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
Weak enhancements to the aurora are possible from Tuesday (21st UTC), but most likely overnight Wednesday into Thursday (22-23rd). This will bring a chance for brief glimpses of visible aurora from northern Scotland and other locations at similar geomagnetic latitudes. However, the shortened hours of darkness at this time of year will significantly limit viewing opportunities.
Southern Hemisphere
Weak enhancements to the aurora are possible from Tuesday (21st UTC), but most likely overnight Wednesday into Thursday (22-23rd). This will bring a chance for brief glimpses of visible aurora from the southernmost parts of New Zealand and other locations at similar geomagnetic latitudes.
Issued at: 17:56 (GMT) on Tue 21 Jul 2026
Forecast overview
Space Weather Forecast Headline: Further Moderate-class flares likely. Chance of G1/Minor Storms days 2-3 (22-23 Jul).
Analysis of Space Weather Activity over past 24 hours
Solar Activity: Moderate with three Moderate class flares, all from the most notable of the five regions on the Earth-facing disc. This is located in the centre disc having rapidly emerged through the last 48 hours. The regions continues to see some growth, along with a number of small mixed polarity spots within its intermediate region. The other four spots remain smaller and simpler, with no significant growth.
No Earth-directed CMEs (Coronal Mass Ejections) were observed.
Solar Wind / Geomagnetic Activity: Solar winds have shown the slow onset of the fast winds of a coronal hole. Solar wind speeds increased from Background to be Slightly Elevated at just over 400km/s. Total Interplanetary Magnetic Field. was initially Weak to Moderate, but increased from 21/0600 UTC to be Moderate to Strong. The north-south component was mainly negative (southward) at first, but strengthened to be Moderate after 21/0600 UTC, before becoming mainly positive (northward) after 21/0840 UTC. Geomagnetic activity was Quiet to Unsettled (Kp 0-3) but became Active (Kp4) 21/0900-1200 UTC.
Energetic Particles / Solar Radiation: The count rate of energetic particles (high energy protons) was at Background with no Solar Radiation storms observed.
Four-Day Space Weather Forecast Summary
Solar Activity: Low to Moderate activity is likely to continue, with further Moderate-class flares likely and a slight chance of Strong-class flares, mainly from AR4493 near the centre disc.
Solar Wind / Geomagnetic Activity: There are no Earth-directed CMEs. Onset of fast winds of the main coronal hole already occurring, with Slight Elevated winds. However these are not expected to peak until later day 2 or into day 3 (22-23 Jul) with a further enhancement likely, with solar wind speeds forecast to reach 500-600km/s. Spells of Unsettled to Active are possible due to the fast wind onset, both day 1-2 (21-22 Jul) and (22-23 Jul), with a chance of an isolated G1 Minor Storm. Otherwise activity is expected to remain Quiet with Unsettled intervals.
Energetic Particles / Solar Radiation: The count rate of energetic particles (high energy protons) is expected to be Background with no Solar Radiation storms occurring. However, any significant eruptions from the central disc sunspot could increase the observed count rates.
Issued at: 12:23 (GMT) on Tue 21 Jul 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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