EGNOS APV-I combined daily availability for (a) pre-storm conditions on 3 November 2023, and (b) storm conditions on 4 November 2023 that corresponded to a significant decrease of the APV-I availability, especially in the Northern Europe (from >99.9% before the storm to ∼80% during the storm). This prompted the notification of “important/severe” degradation to be sent out, and represents one of only 25 occurrences since 2014 where such strong degradation occurred.