Copied from Google's AI Gemini:How solar flares affect satellite radio

• Radio blackouts: A powerful solar flare releases a burst of X-rays and extreme ultraviolet radiation that reaches Earth within minutes. This energy ionizes the Earth's upper atmosphere, or ionosphere, and can degrade or completely absorb the high-frequency radio waves used for satellite communication.
• Disrupted signal path: Satellite radio receivers, including SiriusXM, rely on signals from satellites in geostationary orbit. The increased ionization in the atmosphere caused by a solar flare can disrupt the signal path, leading to temporary signal loss.
• Effect on satellites: The charged particles from solar activity can directly affect the satellites themselves, causing operational anomalies or damaging sensitive electronics.
• Geomagnetic storms: Stronger solar flares are often followed by coronal mass ejections (CMEs)—massive eruptions of solar material. When a CME reaches Earth, it can cause a geomagnetic storm that further disrupts radio signals and creates additional atmospheric interference.

• Multiple satellites: The service uses multiple satellites in different geostationary orbits.
• Ground repeaters: In urban areas where satellite signals are often blocked by buildings, SiriusXM uses ground-based repeaters to ensure uninterrupted service. This network can provide backup signals when solar activity disrupts the direct satellite connection.
• Backup system: If the primary satellite connection is lost, the network is designed to switch to alternate signal paths to maintain service. 

jon wrote:

The ground-based repeater in your area may be off the air.  That happened to me several times over the years. Satellite reception can be almost non-existent in underpasses and when a tall building is between you and the satellite.

I've noticed when driving into or right in Toronto, reception is almost totally from their terrestrial transmitter.