Here are a few weather or sky apps that don't need any signal at all. Free. Most come in versions for both Ipad and Iphone.
TnL. thunder and lightening (measure the distance)
Phases. ( moon phases).
Sunrise & Fall
Star and planet finder
ISS Spotter. (get ISS flyover times)
Planets
SolarCalc. (AKS)
Paid
I used INavX And EyeTides XL for navigation. They work together.