According to an Annapurna spokesperson, moving the film to August is due to that being a great time for female-led movies, as "Crazy Rich Asians and Florence Foster Jenkins have shown. After a summer full of action films and sequels, opening this film in August will be a refreshing change."
It's a solid point, especially with March having the queen of all female flicks on the way with Captain Marvel. I can see why Annapurna would see it as smart to get some distance. There's also Jordan Peele's Us, Dumbo, and Captive State taking up a lot of space. A film like Where'd You Go, Bernadette could get lost in the mix, or perhaps serve as effective counter-programming? I lean towards the latter, but then I don't get paid to figure shit like this out.
It's a gamble, really, because August is pretty packed, too. New Mutants, Hobbs & Shaw, plus Artemis Fowl are going to close this summer out with a band rather than a whimper, so maybe it would be smart to move Bernadette closer to awards season?