I actually emailed my local National Weather Service station awhile back asking if they’d post on Mastodon and even offered them a BlueSky invite and they wrote back saying only Twitter and Facebook were allowed and they’d be everywhere if it was approved by higher ups.

Someone made a BlueSky bot a few months ago for NWS notices and I’m pretty sure they covered every local one. I remember the person who made it asking people to request any missing stations. Not sure if there’s a Mastodon equivalent but you could use a bridge. It won’t help with transit delays or other local government announcements but the weather service stuff is available (via an AtProto <-> ActivityPub bridge if nothing else; it’s not like you interact with the posts so it’d be ideal for a bridge).