Not a bug, the devs have been slowly rolling out this feature since somewhere around the 1960 release. Since not many players were complaining back then, I wouldn't expect a fix any time soon.
In my zone, the rain from the past week seems to have lagged - we had multiple storms load but no rain. Now today all the rain has finally loaded in, but no storm.
It's a larger failure in the [climate] repository, the issue has been known for years now. They tried to patch it several times, for example with the "Paris [Agreement]" Update, but several big server instances including United.States@America, especially it's admin @Donnie refused to work on this issue some time, delaying the timeline of the Patch, possibly until the failure becomes critical.
But I think that the [autumn] patch will arrive on schedule, that could at least partially alleviate the issue for a couple of months, but I think that will only be a hot fix for the symptoms. The bigger repository problems should pop up again unless the [humanity] Framework is reworked.
As per the [climate2000] update, it was decided the weather and climate needed a bit of shaking-up to keep the gameplay interesting and non-trivial. You can counteract it by exiting the game and hoping to respawn in a better area. Though honestly, just give it a try. Maybe it will work out better than anticipated.
Not sure if bug or feature, a lot of the weather systems are getting reworked. Also the coastal regions will be blocked off in a future update? Starting to think the devs are just incompetent