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BGS Global Geomagnetic Activity Forecast

Forecast period
(noon-to-noon GMT) 		Forecast Global Activity level
Average Max
20 AUG-21 AUG ACTIVE STORM G1
21 AUG-22 AUG QUIET ACTIVE
22 AUG-23 AUG QUIET QUIET

For more information about the forecast and activity categories see
geomag.bgs.ac.uk/education/activitylevels.html

Activity during last 24 hours

Global   Local (UK)
Date Average Max At time (UTC) Average Max At time (UTC)
19 AUG-20 AUG QUIET QUIET 18:00-00:00 QUIET QUIET 18:00-00:00

Additional Comments

Solar wind velocity is still elevated at ~550 km/s due to coronal hole (CH) effects but geomagnetic conditions have remained QUIET so far due to the Interplanetary Magnetic Field (IMF) Bz component fluctuating around neutral to positive.
A high-speed stream (HSS) from a second CH and a potential glancing blow from a coronal mass ejection (CME) on 16-Aug are both anticipated to arrive in the first forecast interval. The combined impact of these could increase geomagnetic activity up to STORM G1 levels. Conditions are expected to decline into the second forecast period. There is a chance for some isolated ACTIVE spells as the CH and CME effects wane.
No further enhancement in solar wind parameters is forecast, and activity will return to QUIET in the third window.
Time of forecast: 20 Aug 2026
© UKRI