Weather in calendar

No, but there are third party calendar apps that include weather (fresh air, awesome calendar, horizon 3, others I simply don't know about,...).

I think there are also daily journal apps and organizer apps with both calendar functions and weather forecasts.

You might also want to check out ifttt.com. It's a pretty amazing site that lets you combine functions of apps and services in some pretty interesting ways. I use Google calendar and it's easy to set up an ifttt.com recipe that puts an entry in the calendar that has the weather information. I also use ifttt.com to put an entry into my journal app (Day One) with the weather every day.

I'd add that I have used Week Calendar for many years now, since it first was released in the App Store. It does offer lifetime weather subscriptions for a one time cost of $1.99 per city (at least I think it is per city added but I have only actually ever added the one city where I live). They support, as far as I can tell from the available listings, every country on the planet.

The only reason I suggest it is I have personal experience with it, and it has been around for a very long time (7 or so years now) with excellent and continued support throughout multiple new releases of iOS.

Week Calendar is excellent. It's repeating events capabilities are about the best.