Through IFTTT integration and WebCore I have my setup speak to me when a calendar event is approaching and when it starts. Depending on what calendar you meant, you could query the Microsoft Graph (if using office 365) and that would return a whole host of info from your calendar.
I use this to control some automations based on work schedules and such. It has a hidden attribute that you could use in Core to trigger a contact prior to the event. I could never get it to work in Webcore. Haven’t had time to figure it out.
Tasker has a plug in that can write events to your Google calendar. I use it with another Tasker plugin to read a calendar event and write another event back to the calendar.
So possibly use Webcore to monitor the weather, have it set a virtual contact. Have that work with sharptools to get the signal into Tasker. Have Tasker write a event to your calendar. Maybe even set a reminder via Tasker?
Nowadays this can be done throug variety of ways. Google calender or Yahoo calender. Microsofts Calendar has proven to meet all the needs. My employees have Enterprise E5 to Auto schedule of events or weather forecast can be at one place with innovative add-ons from MS store.