We are aware of users on Microsoft Flight Simulator (2020) reporting issues accessing Live Weather functionality. We have escalated this for investigation, and will update this post when more information is available to share.
Please check our Online Services Monitoring page, which will be manually updated with any status changes.
Update at 11:50 UTC: We have received confirmation that Live Weather Services should now be operational in Microsoft Flight Simulator 2020. Thank you for your patience and quick reporting!