It's a cheap sex comedy that was one of the most surprising successes of Japanese cinema in the 1990s. It was released straight to video, but Bandai gave it a theatrical release after it won the Oslo Film Festival and the Stockholm International Film Festival. It got an inferior sequel shortly afterwards (Weather Woman Returns) and there's an unrelated 2009 Japanese pink film called Weather Girl. The original manga also got a two-episode 1995 anime OVA adaptation.
I'm not a fan. I disliked the important characters and I didn't care about what happened to them.
The eponymous weather woman is Keiko Nakadai, whom we first meet as she masturbates noisily while standing on the edge of a roof. (No, not sitting. Standing up. In her school uniform.) One of her classmates is watching her. The only surprise is that she hasn't drawn a crowd. Nonetheless, she jumps off the roof, kicks him in the head and nearly talks him into committing suicide. (The poor chap's in love with her.) When he returns later in the film, she kicks him in the head again, drawing blood, and says she'll kill him if she sees him again.
That introductory scene also has teleporting characters (due to a lack of shot-to-shot continuity) and a lightning strike from a blameless blue sky.
Years later, Nakadai gets a one-day fill-in job as a weather girl when the usual presenter takes the day off. Nakadai lifts her skirt to camera and takes over the gig regularly when the TV station boss agrees that it's good for ratings. Her antics never stop getting more bonkers. She does a song-and-dance weather presentation, of course wearing very little. She has a corridor lined with blokes who are wearing jockstraps, socks, bow ties and nothing else, although they have roses in their teeth. In fairness, this is so flamboyantly silly that it's memorable... but Nakadai's not even meant to be likeable. I didn't see the point in watching any of this. An unpleasant bitch goes ridiculously over the top. Yes, and? She clashes with rivals. Again, so what? These people tend to be as bad as her, e.g. ordering other reporters to swear an oath of loyalty to be her slaves in what looks like a satanic ritual. I don't care who wins this fight.
I didn't even find her attractive, frankly. The actress, Kei Mizutani, never smiles and has a grim, permanently downturned piranha mouth. I'm sure she'd be less charmless in other roles, though. (The same characters in the OVA look even more openly evil.)
In case you're wondering about those other titles I mentioned, the unsuccessful 1996 film sequel concentrated more on the sex (of which this film has less than you'd think) than on its plot and attempted humour. Mizutani didn't return for it. The completely unrelated 2009 film is even cheaper and more sex-oriented. The 1995 OVAs look better than these films, but of even those I only watched a couple of minutes.
I'd never recommend this film, personally, but I admire how committed it is to being trashy, silly and nasty. There are some crazy gags in there, e.g. weather girls fighting with magical weather-generating superpowers. I like the musical numbers. It was successful. I'm sure it is indeed better than its sequel, but there are some barrels it's not worth scraping.