I was trying to recall Weather With Your’s post-credits interview with Makoto Shinkai and ended up diving into some of the other interviews he has done. On the subject of climate change:
“We’ve always known climate change is happening, but it was always a faraway concept. But now, we can really feel it. Every summer, there’s heavy rainfall [in Japan] and a lot of water-related disasters, but climate change happened, and there’s nothing we can do about it,” the director says. “The world has changed, so I wanted to depict young people, and how they live in this crazy world.”
In another interview, he also referenced our political situation and Trump’s election as inspiration for “this idea of someone having to act as a sacrifice on behalf of a lot of other people” (uhh). In any case, I feel like he knew the implications of what he was putting on screen (though, fwiw, he seems to distance himself from the climate change and political associations in other interviews).
On the flip side, between his interviews and the mixed themes in the movie (e.g. “conform to society and growing up” while also “fuck the police and altruism”), it sounds like he mostly wanted the movie to evoke a divisive dialogue (e.g. “. . . I wanted to have the different generations have the different opinions and have a little bit more of a debate.”)