Question about Xiaomi Redmi Watch 5 Active

Yes, you can receive notifications, including those from WhatsApp, thanks to the smart notifications function. As far as weather forecasts are concerned, there is no specific information on the availability of a dedicated weather app, but you could use notifications to receive weather updates if configured correctly on your smartphone.

You can receive WhatsApp messages and see weather forecasts

I have a redmi xiaomi 12c smartphone. How do I set it up?