Yes. If there’s rain forecasted for the next hour, it’s displayed prominently on the top of the weather interface (it’s hidden if there’s no rain expected). It will also appear on your home screen if you add a weather widget.

FWIW, Google does that (at least on Android). You get a notification if it's expected to rain soon.

Honestly, Dark Sky had been my habitual weather app until Apple killed it, but it doesn't seem as accurate as I expected. I don't know if this means I've been in places where their data is less optimized, or if I'm just noticing it more now that I have to look at other options.

It depends where you are exactly, I had it available in the UK, but in Australia I haven't seen it

I get that from the "Rain Parrot" app.

No, but it's currently in beta in the API, so possibly it will come in the future:

https://developer.apple.com/documentation/weatherkitrestapi/...