In Prizoner of Azkaban, Sirius Black appears on the Muggle news as a wanted fugitive. Uncle Vernon learns later that Sirius is Harry's godfather, so Vernon knows that Wizards may appear on Muggle news.
At the beginning of Order of the Phoenix, Harry is under the window outside, listening to the news – for which Uncle Vernon complains:
Uncle Vernon grunted. "Watching the news. . .” he said scathingly. “I’d like to know what he’s really up to. As if a normal boy cares what’s on the news — Dudley hasn’t got a clue what’s going on, doubt he knows who the Prime Minister is! Anyway, it’s not as if there’d be anything about his lot on our news —” “Vernon, shh!” said Aunt Petunia. “The window’s open!”
How could he forget?
I've seen the argument elsewhere previously that Vernon could have forgotten because it wasn't exactly a big deal to him – but based on how Vernon was so scared of Sirius that he let Harry go to the Quidditch World Cup (in Goblet of Fire) – how could he have forgotten that wizards appear on Muggle news from time to time? This doesn't sit right with me.
What explanation could there be for Vernon stating that there wouldn't be anything about wizards on the news when he knows the truth to be the opposite (although not explicitly stated that the subject in question is magic)?