Everyone who has an iOS device knows how bad the data within the maps app is. Little do people know that Siri's weather functionality also yields inaccurate data. My basis for comparison in this case is Apple's own native Weather App.
As you can see with the attached images the Weather app tells me that it's cold in New York City with a high of 59F and a low of 45F. Siri in the other hand thinks New York City has a high of 88F and a low of 66F.
I've been spurned by Siri's responses not once, not twice but more than I'm willing to admit. So Apple, please fix Siri's weather data.