I know we have a native weather application built into BlackBerry 10 and it seems to work just fine. However, I recently found yWeather in BlackBerry World and it's a real beauty.
The majority of the display is taken up with the current weather conditions and included in these are some extra things we don't always see with weather apps. These include: Humidity, Pressure, Cloud, Rain, Wind, Visibility, Sunrise/Sunset and Moonrise/Moonset - good stuff!
Below the main section is the forecast temperatures for the next ten days which is pretty sweet - we don't normally see that far ahead with many apps. And sharing the weather is simple as there is a share tab at the base of the home screen so you can send the weather to your buddies using any of the accounts/apps that you have associated in your BlackBerry Hub. Plus the app comes with a nice Active Frame - they always make me smile.
Priced at £1.50/$1.99 yWeather is decent value if you ask me. Clearly if you don't care about the weather move along.
Main features of yWeather for BlackBerry: