Recently iOS developer HiDaN has released a jailbreak tweak, WeatherStatusBar10 which will provide this feature. Using this jailbreak app, the current temperature can be displayed just next to the battery indicator.
You can also configure the widget in settings panel of the app. Some of the configurable options are Time interval, force update, enable/disable etc.
This app just fetches the information from the already installed stock weather app. So if you have uninstalled the stock weather app, this tweak may not work.
Currently, it's available in Cydia's BigBoss repository for just $1 for all iOS 10 jailbroken devices.
Are you be desperately missing this feature on your phone? Will you buy this tweak for $1? Let us know your opinion on this app.
Coming to the review of the app, we are more concerned about the font size and its style. Currently, there is no option to change font size, font family, and color of the font. If the developer can make these options configurable, then it is a definite buy for us.