Combining information from this post: https://www.tumblr.com/apple-onigiri/776458752598720512?source=share with climates in our world: https://en.wikipedia.org/wiki/K%C3%B6ppen_climate_classification
Dormont is just 19 degrees away from the equator. This means that just a bit north of Dormont, we've got tropical rainforest (Af). The majority of Mwudu and the Island are also likely around Af.
Vaugard is on the top east of this huge continent, the northern coast of it all under the equator. The closest we've got to that continent is Australia.
That lighter blue is Aw, tropical savanna. I've been looking at Australian calendars here: https://www.bom.gov.au/resources/indigenous-weather-knowledge/indigenous-seasonal-calendars
That is not just a swapping of the "normal" seasons, that's its whole own thing.
Anyway, the wikipedia page on Aw has the data for a northern Australian city here:
When Isa says it's getting cold, he means like 20 degress still. (68 for americans.) That is a very different number from what I think of as cold.
So, rain. You know that trope that Siffrin loves rain after the loops, because that was a dry day and the rain means they're not looping? Consider also their island was very wet and the rain likely feels very normal to him in a way he can't explain.
So, snow. Considering how slow information spreads without phones, it's entirely possible the Vaugardians haven't heart of snow before. They definitely have never seen any. Siffrin will have only seen snow on their travels.
Japan is long. The Okinawa has tropical rainforest climate (Af) at the south and humid continental climate (Dfa&Dfb) up in Hokkaidou. Assuming Ka Bue is similar (BIG assumption considering how irl France isn't tropical), it's not impossible Odile could have grown up with snow. However, also consider her long coat. I reckon she would not be wearing that in above 20 degree weather if she grew up somewhere that got cold enough for snow. She's probably seen it at least, on the way to Vaugarde, depending on how travel routes work.
So! Vaugarde is hot even in the colder times of year, and it's gonna be a few months before they get rain, and this is all before getting into the impact the freezing of the country will have had on the country.
Mira's journey took almost a year after all. How vertical did the time freeze stop at? We know it stopped at Vaugarde's borders. Could the wind still pass through or is that frozen too? Did the rain freeze as it fell? Or did the rain flow through the frozen country, not being able to sink into the ground?
What about the plants and the animals and like the whole ecosystem? Those further north are likely more okay because there doesn't seem to be much change throughout the year. But still! The knock on effects! They exist!
There is just. So much drama and conflict availble post-canon just from the *weather* and then the consequences of the King's invasion on said weather (and also the people! And everything! AHHH), and then you get all the interparty dynamics on top of that? I need to gnaw on it. nomnomnom